CN116607899B - Unconventional coordinated well killing device and method for high-pressure gas wells - Google Patents
Unconventional coordinated well killing device and method for high-pressure gas wells Download PDFInfo
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- E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention relates to an unconventional collaborative well control device and method for a high-pressure gas well, and belongs to the technical field of well drilling and well control. The pressure sensor and the flowmeter which are arranged on a pipeline connecting the wellhead and the blowout preventer collect pressure and flow data, different data collecting points are connected with a computer and transmitted to the computer in real time, the computer processes and analyzes the data according to the collected data in real time, and further controls the opening degree of each valve on the pipeline and the power of a well control fluid injection pump set, two ends of the well control fluid injection pump set are respectively connected with a well control fluid storage tank and an injection pipeline, well control fluid is respectively injected into a drill rod or an annulus, and therefore safe and efficient well control of a high-pressure gas well is achieved. The invention combines two unconventional well-killing methods of a replacement method and a press-back method to cooperate to ensure the safety and timeliness of the well-killing of the high-pressure gas well, and the invention discloses a corresponding cooperative well-killing device, thereby providing a guarantee for realizing safe and efficient drilling of the high-pressure gas well.
Description
Technical Field
The invention relates to an unconventional collaborative well control device and method for a high-pressure gas well, and belongs to the technical field of well drilling and well control.
Background
The conventional well control method is along with the development of national economy, and the requirements of China on oil and gas resources are growing increasingly. Oil and gas resource exploration is gradually trending towards deep and ultra-deep fields. The oil-gas field in the areas of the Tarim basin, the quaiger basin, the Sichuan basin and the like in China has the characteristics of high yield, high pressure, even ultrahigh pressure and the like, once gas invasion occurs in the drilling process, the risk of blowout is easily caused, and the serious well control problem is faced.
The safety well control of the high-pressure gas well is a key technical problem which needs to be solved urgently in the exploration and development processes of most northwest and southwest oil and gas fields in China at present. The method can be mainly divided into a conventional well control method and an unconventional well control method. Conventional well killing methods include engineering, driller, etc., and unconventional well killing methods include displacement, press-back, etc. For the oil-gas well with low common stratum pressure, the conventional well-killing methods such as engineering and driller law can meet the well-killing requirement and recover normal drilling. For a high-pressure gas well, the volume and pressure of an invaded well bore annulus are high, and the conventional well control method can cause the pressure at a well head or a casing shoe to exceed a pressure bearing range, so that the problem of difficult and serious kick or lost circulation is caused, and the method is difficult to be applied. Under the condition that more gas invades a well bore, the difference between wellhead pressure and stratum pressure is small, the problems are also faced by a pressure return method in an unconventional well control method, and the problems of low efficiency, long time, complex operation and the like of a replacement method are solved. In the high-pressure gas well drilling process, once the well is not successfully controlled in time, immeasurable economic loss can be caused, and even casualties are caused, and the deep research is needed to be developed.
In summary, the existing well control method has certain defects for high-pressure gas well control. At present, a safe and efficient well killing method suitable for a high-pressure gas well is not available, and the method is also a key difficulty for restricting safe and efficient drilling of the high-pressure gas well. For this purpose, the present invention is proposed.
Disclosure of Invention
Aiming at the defects of the prior art, in particular to the problems that the existing well killing method is inapplicable in a high-pressure gas well and has low efficiency, the invention provides an unconventional collaborative well killing device and method for the high-pressure gas well, the safety and timeliness of the well killing of the high-pressure gas well are ensured by combining the two unconventional well killing methods of a replacement method and a pressing back method, the corresponding collaborative well killing device is invented, and the guarantee is provided for realizing safe and efficient drilling of the high-pressure gas well.
The invention provides a high-efficiency yield-increasing natural gas hydrate exploitation method, which is used for improving the seepage capability and stability of a reservoir by a horizontal well fracturing and seam making method and a foam cement slurry injection method, improving the natural gas hydrate exploitation yield by a horizontal well depressurization and heat injection exploitation method and providing a guarantee for realizing the commercialized exploitation of natural gas hydrate reservoirs in sea areas in the future.
The invention adopts the following technical scheme:
The unconventional collaborative well killing device for the high-pressure gas well comprises a data acquisition device and a well killing control device, wherein the data acquisition device comprises a well head, a blowout preventer, a pressure sensor A, a pressure sensor B, a flowmeter A, a flowmeter B and a computer;
The well control device comprises a well control liquid injection pump set, a three-way control valve and a well control liquid storage tank, wherein one end of the well control liquid injection pump set is connected with the three-way control valve, the other end of the well control liquid injection pump set is connected with the well control liquid storage tank to provide power for well control liquid injection, one end of the three-way control valve is connected with a wellhead through a pipeline, the other end of the three-way control valve is connected with a blowout preventer through a main pipeline, the three-way control valve is arranged at the junction of the pipeline connected with the wellhead and the main pipeline connected with the blowout preventer, and the pressure sensor A and the flowmeter A are arranged on the pipeline connected with the wellhead and are used for collecting wellhead pressure and fluid flow flowing through the wellhead;
the main pipeline connected with the blowout preventer is provided with a valve B, the main pipeline is connected with a pipeline, the other end of the pipeline is communicated with the atmosphere, the pipeline is provided with a valve C and a valve D, the well control fluid injection pump set, the pressure sensor A, the pressure sensor B, the flowmeter A, the flowmeter B, the valve A, the valve B, the valve C and the valve D are all connected with a computer, and the computer receives and processes pressure and flow data acquired by the pressure sensor A, the pressure sensor B, the flowmeter A and the flowmeter B and controls the opening degree of the valve A, the valve B, the valve C and the valve D and the start and stop of the well control fluid injection pump set.
The working method of the device comprises the following steps:
The pressure sensor and the flowmeter which are arranged on a pipeline connecting the wellhead and the blowout preventer collect pressure and flow data, different data collecting points are connected with a computer and transmitted to the computer in real time, the computer processes and analyzes the data according to the collected data in real time, and further controls the opening degree of each valve on the pipeline and the power of a well control fluid injection pump set, two ends of the well control fluid injection pump set are respectively connected with a well control fluid storage tank and an injection pipeline, well control fluid is respectively injected into a drill rod or an annulus, and therefore safe and efficient well control of a high-pressure gas well is achieved.
The two valves, namely the valve C and the valve D, are arranged on the branch pipe line, so that on one hand, the change of wellhead back pressure can be controlled more accurately, when the valve D is opened, the valve C is opened, and the opening sizes of the two valves are adjusted in real time according to the on-site well control liquid injection condition and wellhead pressure change condition, so that wellhead pressure fluctuation can be reduced, and further, the accurate control of wellhead back pressure is achieved. When closing, valve C is closed first, and then valve D is closed.
The other aspect can reduce the throttling and cooling effect generated by wellhead exhaust, because the gas is directly suddenly changed from very high pressure to normal pressure (namely, the high pressure before the valve and the normal pressure after the valve), the throttling and cooling effect is obvious and can be frozen, two valves are designed, the high-pressure gas is transited to a lower pressure at the first valve, the lower pressure is transited to normal pressure at the second valve, the throttling and cooling effect is still generated at the two valves, the respective cooling effect is far smaller than that of one valve, a certain distance is reserved between the two valves (the valve C, D can be designed to be 5-10 m), and the throttling and cooling effect generated by the high external environment temperature after throttling and cooling is also helpful for relieving the throttling and cooling effect at the two places. In addition, even if the heating and temperature raising measures are adopted on site, the two-valve heating and temperature raising device is easier to be used for the two-valve situation, and is helpful for quickly relieving the throttling and temperature lowering effects at the valve.
The unconventional collaborative well killing method for the high-pressure gas well is realized by the device, and comprises the following steps:
(1) Calculation of injection quantity of well control fluid
According to the well-killing calculation formula of displacement method, the injection parameters of well-killing density and injection flow required by the displacement method can be calculated, so that the pollution-free well-killing liquid with less damage to reservoir can be quickly configured, and preparation is made for quickly carrying out displacement method well-killing, if the well-killing liquid is not prepared on site, the drilling liquid for drilling can be selected to be injected first, so that the initial displacement method well-killing operation can be carried out quickly.
(2) Injection of well killing fluid from drill pipe to displace gas in annulus
Opening a valve A according to the injection flow of the well killing liquid obtained in the step (1), injecting the well killing liquid into an annular space from a drill rod by using the well killing liquid injection drill rod of a well killing liquid injection pump set, sequentially opening a valve C and a valve D to discharge annular air (the discharged air is combusted at an outlet of a branch pipeline in site), so as to realize replacement of the air in the annular space;
(3) Injection of well killing hydraulic return surplus gas from annulus
According to the pressure and flow data monitored in real time, after the pressure and flow data are met, closing a valve A to stop injection of the well control liquid from a drill rod, opening a valve B, closing a valve C and a valve D, and in turn, injecting the well control liquid into the annulus to press the residual gas in the annulus back to the stratum, and simultaneously, monitoring the flow and pressure data of the well control liquid in real time in the pressure and flow data of the well control liquid in the pressure and flow data, and adjusting the power of the well control liquid injected into a pump set in real time;
(4) Injecting plugging material from drill pipe into stratum
When well killing is successful, the valve B is closed, the valve A is opened, drilling fluid containing plugging materials is injected into the target horizon through the drill rod, the bridging effect among plugging material particles is utilized to plug the plugging cracks, the bearing capacity of the target horizon is improved, and guarantee is provided for later-stage safety production.
According to the technical scheme, aiming at the characteristic of difficult well control of the high-pressure gas well, the advantages of a replacement method and a pressing back method in an unconventional well control method are combined, the pressing-back method is adopted to inject the pressing-in liquid into a drill rod to replace part of high-pressure gas in the annular space in the early stage of well control, and the pressing-back method is adopted to inject the pressing-in liquid into the annular space to press the residual gas back into the stratum in the later stage, so that the well control efficiency and the success rate of the high-pressure gas well are improved. The invention can effectively improve the efficiency and the safety of the high-pressure gas well, and provides theoretical support and technical support for the safe drilling of the high-pressure gas well.
Preferably, in step (1), in order to maintain the balance of the bottom hole pressure during the well killing by the displacement method, the gravity difference between the well killing liquid injected from the drill pipe to the bottom hole and the exhaust gas in the annulus is equal to the reduced value of the annulus pressure, as shown in the following formula:
ρzghz-g(ρg0hg0-ρghg)＝pa0-pa (1)
Wherein ρ z is the density of the well control fluid injected from the drill pipe to the bottom of the well, kg/m 3, g is the gravity acceleration, g/cm 3;hz is the height of the well control fluid in the well bore, m, ρ g0 is the initial time gas density, kg/m 3;ρg is the t time gas density, kg/m 3;hg0 is the initial time gas column height in the well bore, m, h g is the t time gas column height in the well bore, m, p a0 is the initial time casing pressure, MPa, p a is the t time casing pressure, MPa, and casing pressure refers to the casing annular pressure at the well mouth (i.e. the pressure at the uppermost end in the annular space);
According to the conservation of matter, the volume of injected kill fluid is equal to the sum of the volume of exhaust gas and the volume of gas reduced by the pressure change, as shown in the following formula:
Wherein Q z is injection flow rate of the well killing liquid by a displacement method, L/s, Q g is gas discharge capacity, L/s, C g is gas compression coefficient, and MPa -1;Vg is gas volume in the annular space of the shaft.
Preferably, in step (1), the density of the injected well control fluid is affected by the pore pressure of the stratum, and in order to meet the well control requirement, the density ρ z of the injected well control fluid is calculated by the following formula:
pk/(gh)<ρz<(pp-pf)/(gh) (3)
Wherein p k is the formation pore pressure, MPa, p p is the formation fracture pressure, MPa, p f is the friction during the flowing of annulus well control fluid, MPa, and h is the vertical depth of the well, m.
Preferably, in the step (3), when the power of the ground well-killing injection pump equipment can perform the well-killing operation by the press-back method, the condition of the press-back method for killing the well is considered to be satisfied.
Preferably, in the step (3), in the process of pressing the gas in the annulus into the stratum, the smooth pressing back operation can be realized only by making the velocity of the underground flow of the well control liquid be greater than the velocity of the rising gas, which puts forward the requirement on the displacement of the well control liquid, and according to the gas-liquid two-phase flow theory, the velocity of the rising gas adopts a calculation formula of the velocity of the rising gas in the slug flow:
Wherein v s is the slip rise speed of the gas in the annulus in the well control fluid, m/s, g is the gravity acceleration, m/s 2;ρL is the density of the well control fluid, kg/m 3, D is the hydraulic diameter, m and C is the dimensionless constant, and can be calculated by a Barnea model:
C=0.1725[(π+1)+K(π-1)]0.5 (5)
Wherein D to is the outer diameter of the drill rod, m, D ci is the inner diameter of the sleeve, m;
According to the calculated v s, the displacement of the well control fluid by the pressing back method can be determined, the displacement of the well control fluid is in direct proportion to the slip rising speed v s of the gas in the well control fluid, and the displacement is calculated by the following formula:
Qa>vsA (7)
Wherein A is the annular cross-sectional area, m 2;Qa is the displacement of well control fluid, and m 3/s.
Preferably, in step (4), after well killing is successful, the drill pipe is lifted to a preset plugging layer, then drilling fluid containing plugging material is injected into the stratum to improve the bearing capacity of the stratum, and then a safe drilling pressure window is reestablished, and as the annular liquid level is lowered and the suction pressure caused by lifting the drill pipe can cause the bottom hole pressure to be lowered in the lifting process of the drill pipe, the well killing fluid needs to be continuously injected into the annular space to keep the bottom hole pressure stable so as to prevent the occurrence of bottom hole gas invasion again, in the process, the change condition of annular space casing pressure is monitored in real time, and the power and the injection displacement of the well killing fluid into the pump set are adjusted accordingly.
Preferably, the safe drilling pressure window established by plugging pressure can be represented by the following formula:
ΔPs＝Pb-Max{Pc,Pk} (8)
Wherein DeltaP s is a safe drilling pressure window established through plugging pressure bearing, P b is stratum fracture pressure after plugging pressure bearing, P c is stratum collapse pressure, MPa, and P k is stratum pore pressure, MPa.
The invention is not exhaustive and can be seen in the prior art.
The beneficial effects of the invention are as follows:
Aiming at the characteristic of difficult well killing of the high-pressure gas well, the invention combines the advantages of a replacement method and a pressing back method in an unconventional well killing method, adopts a replacement method to inject well killing liquid into a drill rod to replace part of high-pressure gas in the annular space in the early stage of well killing, adopts pressing back method to inject well killing liquid into the annular space to press the residual gas back into a stratum in the later stage, and improves the well killing efficiency and success rate of the high-pressure gas well.
Drawings
FIG. 1 is a schematic diagram of a non-conventional collaborative well control apparatus for a high pressure gas well according to the present invention;
FIG. 2 is a schematic diagram of a non-conventional collaborative well killing process of a high-pressure gas well, wherein (a) is a schematic diagram of injecting well killing liquid from a drill rod to replace gas in an annulus in the step (2), (b) is a schematic diagram of injecting well killing liquid from the annulus to return residual gas in the step (3), and (c) is a schematic diagram of injecting plugging materials from the drill rod to a stratum in the step (4);
The well-drilling fluid comprises 1 part of a reservoir, 2 parts of a stratum, 3 parts of a drill bit, 4 parts of a cement sheath, 5 parts of an annulus, 6 parts of a drill rod, 7 parts of a casing, 8 parts of a blowout preventer, 9 parts of a wellhead, 10 parts of a pressure sensor A, 11 parts of a pressure sensor B, 12 parts of a flowmeter A, 13 parts of a flowmeter B, 14 parts of a valve A, 15 parts of a valve B, 16 parts of a valve C, 17 parts of a valve D, 18 parts of a three-way control valve, 19 parts of a well-killing fluid injection pump set, 20 parts of a well-killing fluid storage tank, 21 parts of a computer, 22 parts of a well-killing fluid, 23 parts of high-pressure gas in the annulus and 24 parts of a drilling fluid containing plugging materials.
Detailed Description
In order to better understand the technical solutions in the present specification, the following description will clearly and completely describe the technical solutions in the embodiments of the present invention, but not limited thereto, and the present invention is not fully described according to the conventional technology in the art.
Example 1
The unconventional collaborative well control device for the high-pressure gas well comprises a data acquisition device and a well control device, wherein the data acquisition device comprises a wellhead 9, a blowout preventer 8, a pressure sensor A10, a pressure sensor B11, a flow meter A12, a flow meter B13 and a computer 21, wherein 1 is a reservoir, 2 is a stratum, 3 is a drill bit, 4 is a cement ring, 5 is an annulus, 6 is a drill rod, and 7 is a casing;
The well control device comprises a well control fluid injection pump set 19, a three-way control valve 18 and a well control fluid storage tank 20, wherein one end of the well control fluid injection pump set 19 is connected with the three-way control valve 18, the other end of the well control fluid injection pump set is connected with the well control fluid storage tank 20 to provide power for well control fluid injection, one end of the three-way control valve 18 is connected with a wellhead 9 through a pipeline, the other end of the three-way control valve is connected with a blowout preventer 8 through a main pipeline, the three-way control valve is arranged at the junction of the pipeline connected with the wellhead and the main pipeline connected with the blowout preventer, and a pressure sensor A10 and a flowmeter A12 are arranged on the pipeline connected with the wellhead and used for collecting wellhead pressure and fluid flow flowing through the wellhead;
the main pipeline connected with the blowout preventer is provided with a valve B15, the main pipeline is connected with a pipeline, the other end of the pipeline is communicated with the atmosphere, the pipeline is provided with a valve C16 and a valve D17, a well control fluid injection pump set 19, a pressure sensor A10, a pressure sensor B11, a flow meter A12, a flow meter B13, a valve A14, a valve B15, a valve C16 and a valve D17 are all connected with a computer 21, and the computer 21 receives and processes pressure and flow data acquired by the pressure sensor A10, the pressure sensor B11, the flow meter A12 and the flow meter B13 and controls the opening degree of the valve A14, the valve B15, the valve C16 and the opening degree of the valve D17 and the start and stop of the well control fluid injection pump set.
The working method of the device comprises the following steps:
The pressure sensor and the flowmeter which are arranged on a pipeline connecting the wellhead and the blowout preventer collect pressure and flow data, different data collecting points are connected with a computer and transmitted to the computer in real time, the computer processes and analyzes the data according to the collected data in real time, and further controls the opening degree of each valve on the pipeline and the power of a well control fluid injection pump set, two ends of the well control fluid injection pump set are respectively connected with a well control fluid storage tank and an injection pipeline, well control fluid is respectively injected into a drill rod or an annulus, and therefore safe and efficient well control of a high-pressure gas well is achieved.
The two valves, namely the valve C16 and the valve D17, are arranged on the branch pipe line, so that on one hand, the change of wellhead back pressure can be controlled more accurately, when the valve is opened, the valve D17 is opened, the valve C16 is opened, and the opening sizes of the two valves are adjusted in real time according to the on-site well killing liquid injection condition and the wellhead pressure change condition, so that wellhead pressure fluctuation can be reduced, and further, the accurate control of wellhead back pressure is achieved. When closing, valve C16 is closed, and then valve D17 is closed.
The other aspect can reduce the throttling and cooling effect generated by wellhead exhaust, because the gas is directly suddenly changed from very high pressure to normal pressure (namely, the high pressure before the valve and the normal pressure after the valve), the throttling and cooling effect is obvious and can be frozen, two valves are designed, the high-pressure gas is transited to a lower pressure at the first valve, the lower pressure is transited to normal pressure at the second valve, the throttling and cooling effect is still generated at the two valves, the respective cooling effect is far smaller than that of one valve, a certain distance is reserved between the two valves (the valve C, D can be designed to be 5-10 m), and the throttling and cooling effect generated by the high external environment temperature after throttling and cooling is also helpful for relieving the throttling and cooling effect at the two places. In addition, even if the heating and temperature raising measures are adopted on site, the two-valve heating and temperature raising device is easier to be used for the two-valve situation, and is helpful for quickly relieving the throttling and temperature lowering effects at the valve.
Example 2
The unconventional collaborative well killing method for the high-pressure gas well is realized by the device, and comprises the following steps:
(1) Calculation of injection quantity of well control fluid
According to the well-killing calculation formula of displacement method, the injection parameters of well-killing density and injection flow required by the displacement method can be calculated, so that the pollution-free well-killing liquid with less damage to reservoir can be quickly configured, and preparation is made for quickly carrying out displacement method well-killing, if the well-killing liquid is not prepared on site, the drilling liquid for drilling can be selected to be injected first, so that the initial displacement method well-killing operation can be carried out quickly.
In the process of well killing by a displacement method, in order to maintain the balance of bottom hole pressure, the gravity difference generated by the well killing liquid injected into the bottom hole from a drill rod and the discharged gas in the annulus is equal to the reduction value of the annulus pressure, and the formula is as follows:
ρzghz-g(ρg0hg0-ρghg)＝pa0-pa (1)
Wherein ρ z is the density of the well control fluid injected from the drill pipe to the bottom of the well, kg/m 3, g is the gravity acceleration, g/cm 3;hz is the height of the well control fluid in the well bore, m, ρ g0 is the initial time gas density, kg/m 3;ρg is the t time gas density, kg/m 3;hg0 is the initial time gas column height in the well bore, m, h g is the t time gas column height in the well bore, m, p a0 is the initial time casing pressure, MPa, p a is the t time casing pressure, MPa, and casing pressure refers to the casing annular pressure at the well mouth (i.e. the pressure at the uppermost end in the annular space);
According to the conservation of matter, the volume of injected kill fluid is equal to the sum of the volume of exhaust gas and the volume of gas reduced by the pressure change, as shown in the following formula:
Wherein Q z is injection flow rate of the well killing liquid by a displacement method, L/s, Q g is gas discharge capacity, L/s, C g is gas compression coefficient, and MPa -1;Vg is gas volume in the annular space of the shaft.
The density of the injected well control fluid is affected by the pore pressure of the stratum, and in order to meet the well control requirement, the density ρ z of the injected well control fluid is calculated by the following formula:
pk/(gh)<ρz<(pp-pf)/(gh) (3)
Wherein p k is the formation pore pressure, MPa, p p is the formation fracture pressure, MPa, p f is the friction during the flowing of annulus well control fluid, MPa, and h is the vertical depth of the well, m.
(2) Injection of well killing fluid from drill pipe to displace gas in annulus
According to the injection flow rate of the well control fluid obtained in the step (1), opening a valve A14, injecting the well control fluid into a drill rod 6 of a well control fluid injection pump set, injecting the well control fluid 22 into an annulus 5 from the drill rod 6, and sequentially opening a valve C16 and a valve D17 to discharge high-pressure gas 23 in the annulus (the discharged gas is combusted at the outlet of a branch pipeline in the field in general), so that the high-pressure gas in the annulus is replaced by injecting the well control fluid;
The well killing liquid in the injection ring keeps the bottom hole pressure stable together with the ring air gravity and the wellhead back pressure, and prevents stratum fluid from continuously invading the well shaft. Two valves C16 and D17 are designed on an exhaust pipe line of a wellhead, so that multistage throttling is realized, on one hand, the change of back pressure of the wellhead can be controlled more accurately, and on the other hand, the throttling and cooling effect generated by wellhead exhaust can be reduced, and the risk of icing or blocking the pipeline by hydrate is reduced. In addition, in order to avoid the problem of wellhead throttling blockage, heating devices can be additionally arranged near the valve C16 and the valve D17.
In order to improve the replacement efficiency of high-pressure gas in the annular space, a dynamic replacement mode is adopted, namely, the injection of the bottom hole pressure well liquid and the discharge of wellhead gas are carried out simultaneously. In the process, the speed and the pressure of the well control liquid injected from the drill rod and the flow and pressure data of the gas discharged from the annulus are monitored in real time, the dynamic change of the injection displacement of the well control liquid is calculated in real time according to the monitored data, the opening of the valve A, C, D and the power of the well control liquid injection pump set are adjusted in real time according to the dynamic change, the replacement efficiency of high-pressure gas in the annulus is improved, and precious time is striven for the in-situ well control operation which is in charge of the second.
According to the monitored flow and pressure data of the gas discharged from the annulus, the injection rate of the well killing liquid is calculated in real time and is compared with the monitored injection rate of the well killing liquid, so that the injection rate of the well killing liquid is regulated up, regulated down or kept unchanged, the injection rate is influenced by the opening of the valve A and the power of the pump group of the well killing liquid injection pump and is in positive correlation, and then the opening of the valve A and the power of the pump group of the well killing liquid injection pump are regulated according to the requirement of the injection rate of the well killing liquid. In addition, if the flow rate of the exhaust gas from the annulus is too low, the opening of the valve C, D needs to be appropriately increased, which depends on the situation.
(3) Injection of well killing hydraulic return surplus gas from annulus
According to the pressure and flow data monitored by the pressure sensor A10, the pressure sensor B11, the flow meter A12 and the flow meter B13 in real time, after the pressure-return method well killing condition is met (namely, the power of the ground well killing injection pump equipment can carry out the pressure-return method well killing operation), closing the valve A14 to stop injecting the well killing liquid 22 from the drill pipe 6, opening the valve B15, closing the valve C16 and the valve D17, and in turn, pressing the residual gas in the annulus back to the stratum by injecting the well killing liquid into the annulus, and simultaneously, monitoring the flow and the pressure data of the well killing liquid in real time in the process of pressing back, and adjusting the power of the well killing liquid injection pump set in real time;
In the process of pressing gas in an annulus into a stratum, the smooth pressing back operation can be realized only by enabling the velocity of the underground flow of the well killing liquid to be larger than the gas rising velocity, the requirement is put forward on the displacement of the well killing liquid, and according to the gas-liquid two-phase flow theory, the gas rising velocity adopts a gas rising velocity calculation formula in slug flow:
Wherein v s is the slip rise speed of the gas in the annulus in the well control fluid, m/s, g is the gravity acceleration, m/s 2;ρL is the density of the well control fluid, kg/m 3, D is the hydraulic diameter, m and C is the dimensionless constant, and can be calculated by a Barnea model:
C=0.1725[(π+1)+K(π-1)]0.5 (5)
Wherein D to is the outer diameter of the drill rod, m, D ci is the inner diameter of the sleeve, m;
According to the calculated v s, the displacement of the well control fluid by the pressing back method can be determined, the displacement of the well control fluid is in direct proportion to the slip rising speed v s of the gas in the well control fluid, and the displacement is calculated by the following formula:
Qa>vsA (7)
Wherein A is the annular cross-sectional area, m 2;Qa is the displacement of well control fluid, and m 3/s.
Meanwhile, flow rate of the well control fluid and wellhead casing pressure change data are monitored in real time in the pressing back process, power of the well control fluid injection pump set and well control fluid injection rate are adjusted in real time, when the well control casing pressure is found to be obviously increased, the well control fluid injection rate is excessively high, at the moment, the well control fluid injection rate needs to be reduced by adjusting the power of the well control fluid injection pump set, and if the well control casing pressure is stable, the current well control fluid injection pump set power is kept unchanged. As the kill fluid is gradually injected into the annulus, the gas is gradually forced back into the formation, and the annulus casing pressure gradually decreases due to the increase in pressure of the kill fluid column. After all of the remaining gas in the annulus is pressed back into the formation, the annulus casing pressure will remain unchanged, thereby indicating successful well control.
(4) Injecting plugging material from drill pipe into stratum
During the well killing process by the push-back method, the stratum can be fractured to generate cracks, and the stratum can also be provided with cracks, so that the condition of drilling fluid leakage can occur. When well killing is successful, the drill rod is lifted to a preset plugging layer, then drilling fluid containing plugging materials is injected into the stratum to improve the bearing capacity of the stratum, and then a safe drilling pressure window is reestablished, because in the lifting process of the drill rod, the liquid level of the annulus is lowered, and the suction pressure caused by lifting of the drill rod is reduced to cause bottom hole pressure, continuous injection of the well killing fluid into the annulus is needed to keep the bottom hole pressure stable, so that the occurrence of bottom hole gas invasion is prevented, in the process, the change condition of the annular sleeve pressure is monitored in real time, the power and the injection displacement of a well killing fluid injection pump set are adjusted according to the change condition of the annular sleeve pressure, specifically, if the annular sleeve pressure is increased, the pressure of a liquid column in the annulus is reduced (namely, the liquid level is lowered), the injection displacement of the well killing fluid is required to be increased by improving the power of the well killing fluid injection pump set, and the well killing fluid is supplemented into the annulus to avoid the occurrence of gas invasion again at the bottom hole.
When the drill pipe 6 is lifted to a preset plugging layer, the valve B15 is closed, the valve A14 is opened, the drilling fluid 24 containing plugging material which is prepared in advance is injected to a target layer through the drill pipe by a well killing fluid injection pump set, and the plugging material enters the plugging layer along with the drilling fluid. The bridging effect among the plugging material particles is used for plugging the plugging cracks, so that the bearing capacity of the target stratum is improved
The safe drilling pressure window established by plugging pressure bearing can be represented by the following formula:
ΔPs＝Pb-Max{Pc,Pk} (8)
Wherein DeltaP s is a safe drilling pressure window established through plugging pressure bearing, P b is stratum fracture pressure after plugging pressure bearing, P c is stratum collapse pressure, MPa, and P k is stratum pore pressure, MPa.
While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that various modifications and adaptations can be made without departing from the principles of the present invention, and such modifications and adaptations are intended to be comprehended within the scope of the present invention.
Claims (7)
1. The unconventional collaborative well control method for the high-pressure gas well is characterized by being realized by a unconventional collaborative well control device for the high-pressure gas well, wherein the unconventional collaborative well control device for the high-pressure gas well comprises a data acquisition device and a well control device, and the data acquisition device comprises a well mouth, a blowout preventer, a pressure sensor A, a pressure sensor B, a flowmeter A, a flowmeter B and a computer;
The well control device comprises a well control liquid injection pump set, a three-way control valve and a well control liquid storage tank, wherein one end of the well control liquid injection pump set is connected with the three-way control valve, the other end of the well control liquid injection pump set is connected with the well control liquid storage tank to provide power for well control liquid injection, one end of the three-way control valve is connected with a wellhead through a pipeline, the other end of the three-way control valve is connected with a blowout preventer through a main pipeline, and the pressure sensor A and the flowmeter A are arranged on the pipeline connected with the wellhead and are used for collecting wellhead pressure and fluid flow flowing through the wellhead;
The main pipeline connected with the blowout preventer is provided with a valve B, the main pipeline is connected with a branch pipeline, the other end of the branch pipeline is communicated with the atmosphere, the branch pipeline is provided with a valve C and a valve D, the well control fluid injection pump set, the pressure sensor A, the pressure sensor B, the flowmeter A, the flowmeter B, the valve A, the valve B, the valve C and the valve D are all connected with a computer, and the computer receives and processes pressure and flow data acquired by the pressure sensor A, the pressure sensor B, the flowmeter A and the flowmeter B and controls the opening degree of the valve A, the valve B, the valve C and the valve D and the start and stop of the well control fluid injection pump set;
the unconventional collaborative well killing method of the high-pressure gas well comprises the following steps:
(1) Calculation of injection quantity of well control fluid
Calculating the density and injection flow of the well control liquid required by the well control by the displacement method according to the well control calculation formula by the displacement method, and configuring the pressure storage well liquid;
(2) Injection of well killing fluid from drill pipe to displace gas in annulus
According to the injection flow of the well control liquid obtained in the step (1), opening a valve A, injecting the well control liquid into a drill rod of a well control liquid injection pump set, injecting the well control liquid into an annulus from the drill rod, and sequentially opening a valve C and a valve D to discharge gas in the annulus, thereby realizing replacement of the gas in the annulus;
(3) Injection of well killing hydraulic return surplus gas from annulus
According to the pressure and flow data monitored in real time, after the pressure and flow data are met, closing a valve A to stop injection of the well control liquid from a drill rod, opening a valve B, closing a valve C and a valve D, and in turn, injecting the well control liquid into the annulus to press the residual gas in the annulus back to the stratum, and simultaneously, monitoring the flow and pressure data of the well control liquid in real time in the pressure and flow data of the well control liquid in the pressure and flow data, and adjusting the power of the well control liquid injected into a pump set in real time;
(4) Injecting plugging material from drill pipe into stratum
And after well killing is successful, closing the valve B, opening the valve A, injecting drilling fluid containing plugging materials into the target horizon through the drill rod, and plugging the lost circulation cracks by utilizing bridging action among plugging material particles.
2. The method of claim 1, wherein in step (1), in order to maintain the balance of the bottom hole pressure during the displacement method well control, the gravity difference between the well control fluid injected into the bottom hole from the drill pipe and the gas discharged from the annulus is equal to the decrease of the annulus pressure, as shown in the following formula:
ρzghz-g(ρg0hg0-ρghg)＝pa0-pa (1)
Wherein ρ z is the density of the well control fluid injected from the drill rod to the bottom of the well, kg/m 3, g is gravity acceleration, g/cm 3;hz is the height of the well control fluid in the well shaft, m, ρ g0 is the initial time gas density, kg/m 3;ρg is the t time gas density, kg/m 3;hg0 is the initial time gas column height in the well shaft, m, h g is the t time gas column height in the well shaft, m, p a0 is the initial time casing pressure, MPa, p a is the t time casing pressure, MPa, and casing pressure refers to the casing annular pressure at the well head;
According to the conservation of matter, the volume of injected kill fluid is equal to the sum of the volume of exhaust gas and the volume of gas reduced by the pressure change, as shown in the following formula:
Wherein Q z is injection flow rate of the well killing liquid by a displacement method, L/s, Q g is gas discharge capacity, L/s, C g is gas compression coefficient, and MPa -1;Vg is gas volume in the annular space of the shaft.
3. The method of claim 2, wherein in step (1), the density of the injected well control fluid is affected by the pore pressure of the stratum, and in order to meet the well control requirement, the density ρ z of the injected well control fluid is calculated by the following formula:
pk/(gh)<ρz<(pp-pf)/(gh) (3)
Wherein p k is the formation pore pressure, MPa, p p is the formation fracture pressure, MPa, p f is the friction during the flowing of annulus well control fluid, MPa, and h is the vertical depth of the well, m.
4. The method of claim 3, wherein in step (3), the condition of the snubbing is considered to be satisfied when the power of the surface snubbing injection pump equipment is capable of performing snubbing operations.
5. The method of claim 4, wherein in step (3), the velocity of the underground flow of the well-killing fluid is required to be greater than the velocity of the gas rise in the process of pressurizing the gas in the annulus, and the velocity of the gas rise adopts a calculation formula of the velocity of the gas rise in the slug flow according to the theory of the gas-liquid two-phase flow:
Wherein v s is the slip rise speed of the gas in the annulus in the well control fluid, m/s, g is the gravity acceleration, m/s 2;ρL is the density of the well control fluid, kg/m 3, D is the hydraulic diameter, m, C is the dimensionless constant, calculated by a Barnea model:
C=0.1725[(π+1)+K(π-1)]0.5 (5)
Wherein D to is the outer diameter of the drill rod, m, D ci is the inner diameter of the sleeve, m;
And determining the displacement of the well killing liquid by a press-back method according to the v s obtained by calculation, wherein the displacement of the well killing liquid is in direct proportion to the slip rising speed v s of the gas in the well killing liquid, and the displacement is obtained by calculation according to the following formula:
Qa>vsA (7)
Wherein A is the annular cross-sectional area, m 2;Qa is the displacement of well control fluid, and m 3/s.
6. The method of claim 5, wherein in step (4), after the well is successfully controlled, the drill pipe is lifted to a predetermined plugging layer, and then the drilling fluid containing plugging material is injected into the stratum to increase the bearing capacity of the stratum, so that the safe drilling pressure window is reestablished, the pressure of the bottom hole is reduced due to the descending of the liquid level of the annulus and the suction pressure caused by the lifting of the drill rod, so that the well killing liquid is continuously injected into the annulus to keep the bottom hole pressure stable, the occurrence of well bottom gas invasion is prevented, in the process, the change condition of the annular sleeve pressure is monitored in real time, and the power and the injection displacement of the well killing liquid injection pump set are adjusted accordingly.
7. The method of claim 6, wherein the safe drilling pressure window established by plugging the bearing is represented by the following formula:
αPs＝Pb-Max{Pc,Pk} (8)
Wherein alpha P s is a safe drilling pressure window established through plugging pressure bearing, MPa, P b is stratum fracture pressure after plugging pressure bearing, MPa, P c is stratum collapse pressure, MPa, and P k is stratum pore pressure, MPa.
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