CN110598248A - A Discrimination Method for Killing Stage and End Conditions of Direct Pushing Method - Google Patents

Abstract

The invention discloses a method for judging the well killing stage and the end condition of the direct push method, which comprises the following steps: S1, inputting the well shut-in data, formation and fluid physical property parameters after shut-in through geological logging data and adjacent well data; S2 1. Process the data and parameters described in S1 and draw the theoretical wellbore pressure change curve; S3. Process the data collected through the wellhead pressure sensor and the bottom hole pressure sensor and draw the actual wellbore pressure change curve; S4. Analyze the theoretical wellbore pressure The variation curve and the actual wellbore pressure variation curve are used to identify and judge the well killing stage; S5, to judge the end condition of well killing. The beneficial effect of the present invention is: combined with the change of the flow resistance in the well killing process, the well head pressure change law is used to judge the well killing stage, so as to accurately control the well killing process, and guarantee the safe construction of the well killing and the protection of the reservoir.

Description

A Discrimination Method for Killing Stage and End Conditions of Direct Pushing Method

technical field

The invention relates to the technical field of petroleum drilling well control, in particular to a method for judging the well killing stage and the end condition of the direct push method.

Background technique

At present, as my country's requirements for environmental protection become more stringent, the pressure on environmental protection for oil and gas drilling has further increased. However, with the continuous extension and expansion of oil and gas exploration and development, from land to tidal flats and shallow seas, and from shallow to deep layers, drilling is becoming more and more difficult, and overflow occurs from time to time, which is difficult to completely avoid. The discharge of overflow and contaminated drilling fluid has become a difficult problem in the traditional throttling circulation well control method, especially when drilling formations with toxic gases such as hydrogen sulfide, and when the circulation cannot be established such as drill pipe damage, the traditional well control Technology cannot control overflow quickly. In order to deal with complex formations, implement fast drilling with safety and quality, and take into account the national requirements for environmental protection, well control technology must be taken as an important content of research and development.

The direct push well kill well control technology can be used regardless of whether there is a drilling tool in the wellbore under the precondition of shutting in the well, and the overflow can be quickly pushed back to the formation by using the high pressure at the wellhead, especially for drilling encounters such as hydrogen sulfide, etc. Toxic gas gas invasion, the direct push method can effectively prevent toxic gas from reaching the ground. The direct push method kill well control technology can effectively avoid the pollution of the overflow to the environment while quickly controlling the overflow, which meets the requirements of environmental protection. However, the existing direct push method kill well control technology does not compare the variation law of wellbore pressure in the actual well killing stage with the theoretical wellbore pressure change pattern in the well killing stage, and judge the actual well killing stage based on the idea of reservoir protection. The composition of the fluid in the wellbore and the pressure of the hydrostatic column make it impossible to accurately grasp the well killing process, and it is impossible to provide safety guarantee for the wellbore and formation during the well killing process. Therefore, there is an urgent need for a transduction method that combines the change of flow resistance in the well killing process and the variation law of wellhead pressure to judge the well killing stage, so as to accurately control the well killing process, and guarantee the safe construction of the well killing and the protection of the reservoir. Distinguishing method of kill stage and end condition.

Contents of the invention

The purpose of the present invention is to overcome the disadvantages of the prior art, and provide a method for judging the well killing stage and the end condition of the direct push method.

The object of the present invention is achieved through the following technical solutions: a method for discriminating the kill stage and end condition of a direct push method, which comprises the following steps:

S1. Enter the shut-in data, formation and fluid physical parameters after shut-in through geological logging data and adjacent well data;

S2. Process the data and parameters described in S1 and draw a theoretical wellbore pressure variation curve;

S3. Process the data collected by the wellhead pressure sensor and the bottom hole pressure sensor and draw the actual wellbore pressure change curve;

S4. Analyze the theoretical wellbore pressure change curve and the actual wellbore pressure change curve, identify and judge the killing stage;

S5. Discrimination of well killing end conditions.

The step S2 includes the following sub-steps:

S21. Calculating the well killing displacement and the killing fluid density;

S22. Determine the pressure composition relationship in the wellbore during the well killing process;

S23, calculating the gas column pressure;

S24. Drawing the change law of wellbore pressure in the well killing stage and analyzing the theoretical well killing curve;

The step S3 includes the following sub-steps:

S31. Transmit the collected data to the data processing system through the signal receiver through the wellhead pressure sensor and the bottom hole pressure sensor;

S32. The data processing system performs cleaning and noise reduction preprocessing on the data;

S33. The data processing system analyzes the change law of the wellbore pressure in real time, and draws the actual wellbore pressure change curve.

In the step S4, the well killing stage is judged according to the similarity.

The specific conditions for judging the well killing end condition in the step S5 are that the overflow in the wellbore is completely pushed back to the formation and the hydrostatic column pressure in the wellbore meets the well control requirements.

The formation and fluid physical property parameters described in step S1 include formation pressure, rock porosity, permeability, production layer thickness, gas density, gas viscosity, wellbore size and formation pressure boundary; post-well shut-in data include wellbore structure , drilling tool assembly, shut-in casing pressure, shut-in vertical pressure, drilling fluid outlet density, drilling fluid viscosity, drilling fluid density, fluid distribution in the wellbore and fluid distribution in the wellbore.

The step S3 also includes the step of killing a physical model, and the killing physical model includes a blowout preventer group (1) arranged on the top of the well, a signal receiver (2) arranged on the blowout preventer group (1) ), the signal receiver (2) is electrically connected with the data processing system, the bottom of the well is provided with a bottom hole pressure sensor (3), the top of the well is provided with a wellhead pressure sensor (4), the wellhead pressure sensor (4) and the bottom hole pressure sensor ( 3) are all electrically connected to the signal receiver (2), and the blowout preventer group (1) is provided with a drill pipe (5), the drill pipe (5) extends downward in the well, and a drill bit ( 6).

The present invention has the following advantages:

(1), the present invention calculates the wellbore pressure in each stage of well killing by theoretical calculation, obtains the law of wellbore pressure change in each stage, and the law of change of well killing measured data is compared with the law of wellbore pressure change in theoretical well killing stage, and draws In the actual well killing stage, based on the idea of reservoir protection, by judging the fluid composition and hydrostatic column pressure in the wellbore, a process for judging the end conditions of well killing by direct push method is proposed, which can reduce the risk of polluting the reservoir.

(2), the present invention provides guarantee for the wellbore and formation safety in the well killing process through the accurate grasp of the well killing process, thereby providing theoretical guidance for the implementation of the well killing operation.

Description of drawings

Fig. 1 is the discriminating flowchart of the present invention;

Fig. 2 is the flow chart of judging the end condition of well killing;

Fig. 3 is the schematic diagram of well killing physical model;

In the figure, 1-BOP group, 2-Signal receiver, 3-Bottomhole pressure sensor, 4-Wellhead pressure sensor, 5-Drill pipe, 6-Drill bit, 7-Killing fluid, 8-Drilling fluid, 9 -gas-liquid two-phase flow, 10-gas column, 11-formation.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing, protection scope of the present invention is not limited to the following:

As shown in Fig. 1, a method for discriminating the kill stage and the end condition of the direct push method, it includes the following steps:

S1. Enter the shut-in data, formation and fluid physical property parameters through geological logging data and adjacent well data. The formation and fluid physical property parameters include formation pressure, rock porosity, permeability, production layer thickness, gas density, Gas viscosity, wellbore size and formation pressure boundaries; post-well shut-in data include well structure, drilling tool assembly, shut-in casing pressure, well shut-in standing pressure, drilling fluid outlet density, drilling fluid viscosity, drilling fluid density, wellbore Fluid distribution and fluid distribution in the wellbore;

S2. Processing the data and parameters described in S1 and drawing a theoretical wellbore pressure change curve, including the following sub-steps:

S21. Calculating the kill displacement and the kill fluid density, the specific calculation steps are as follows:

The design principle of the killing fluid density is: under the condition of ensuring the safety of the wellbore, use a higher killing fluid density as much as possible to quickly establish a balance to ensure that the drilling fluid is not pushed back or pushed back less into the formation. The calculation formula is as follows:

However, if designed according to this principle, sometimes the formation may be leaked because the density of the killing fluid is too high and the wellbore pressure is too high during the killing process. At this time, it is necessary to appropriately reduce the density of the killing fluid through trial calculation to meet the safety requirements of the wellbore, but it cannot be lower than the minimum density of the killing fluid ρ _k ′. The calculation formula is as follows:

In the formula, P _e additional safety pressure, 3-5MPa; H is well depth, m; h _m is the length of uncontaminated drilling fluid in the original wellbore, m; g is gravity acceleration, m/s ² ;

The design principle of the killing fluid displacement is: the downward speed of the killing fluid must be greater than the upward slipping speed of the bubbles, so as to ensure that the gas in the wellbore is completely removed and the well is successfully killed. However, the killing displacement cannot exceed the formation-wellbore safety conditions, and the formation cannot be crushed and the wellbore damaged, causing more serious accidents. The calculation formula is as follows:

The formula for calculating the minimum killing fluid displacement is as follows:

Q _min = v _gr A (3)

v _gr is gas slippage velocity, m/s; ρ _m and ρ _g are drilling fluid density and gas density, kg/m ³ respectively; σ is surface tension, 10 ^-3 N/m; A is annular cross-sectional area, m ² ;

The maximum displacement calculation formula is as follows:

Q _max <min(Q ₁ ,Q ₂ ,Q ₃ ,Q ₄ ) (5)

In the formula: Q ₁ is the maximum kill displacement allowed by the wellhead equipment under pressure, m ³ /s; Q ₂ is the maximum kill displacement allowed by the bottom hole fracture pressure, m ³ /s; Q ₃ is the casing shoe The maximum kill displacement allowed by the fracture pressure, m ³ /s; Q ₄ is the maximum kill displacement allowed by the internal pressure of the casing, m ³ /s;

S22. Determine the pressure composition relationship in the wellbore during the well killing process. The specific steps are as follows:

In the initial stage of well killing, the bottom hole pressure may be less than the formation pressure. At the moment of killing the well, flow friction occurs, and then as the gas is continuously compressed, the force of the compressed gas increases and the wellhead pressure continues to rise until the bottom hole pressure is equal to the formation pressure. This stage is called the dynamic sealing stage. At this stage, there is the following relationship between wellhead pressure and flow resistance:

P _a ＝P _C +P _f +P _p -P _h (6)

In the formula: P _a is the wellhead pressure, MPa; P _h is the hydrostatic column pressure, MPa; P _f is the flow friction, MPa; P _C is the force generated by compressing natural gas, MPa; P _p is the formation pressure, MPa.

When the bottom hole pressure is equal to the formation pressure, the overflow fluid begins to be pushed back to the formation, and the gas compression force reaches the maximum at this time, and gradually decreases until zero as the wellbore gas phase is pushed back to the formation. 1. When the liquid phase is pushed back into the formation, its seepage resistance is different, and there will be a turning point in the kill curve. After the turning point, due to the change of the fluid type in the wellbore, the fluid flow friction resistance and hydrostatic column pressure composition in the wellbore will also change. , the wellhead pressure has the following relationship with various pressures in the wellbore:

P _a =P _C +P _f +P _p +ΔP-P _h (7)

In the formula: P _a is the wellhead pressure, MPa; P _h is the hydrostatic column pressure, MPa; P _f is the flow friction, MPa; P _C is the force generated by compressing natural gas, MPa; P _p is the formation pressure, MPa; _i is the seepage resistance of a certain type of fluid, MPa;

During the killing process, the pressure in the wellbore changes continuously with the well killing, and the wellhead pressure changes with the change of the flow resistance. The flow resistance is composed of fluid flow friction, seepage resistance generated during the process of fluid being pushed back into the formation, formation pressure, and gas column pressure generated after the gas column in the wellbore is compressed. The composition of various pressures at different stages is shown in Table 1 .

Table 1 Composition of various pressures in different well killing stages

S23. Calculation of gas column pressure, the specific calculation steps are as follows:

The pressure in the wellbore includes the hydrostatic column pressure, and its calculation formula is as follows:

P _hi ＝0.0098ρ _i H _i

The formula for calculating flow friction is as follows:

In the formula, f _i is the Fanning friction coefficient of a certain type of fluid; ρ _i is the density of a certain type of fluid, Kg/m ³ ; D _w , D _z are the inner diameter of the casing and the outer diameter of the drill string, mm; H _i is the density of a certain type of fluid The length in the wellbore, m; v is the killing fluid velocity, m/s;

The formula for calculating seepage resistance is as follows:

In the formula: Q is the well killing displacement, m ³ /d; K _φ is the formation flow coefficient of the fluid, μm ² ; μ _i is the viscosity of a certain fluid, mPa·s; ΔP _i is the seepage resistance of a certain fluid, MPa; r _e , r _w are the outer edge radius and wellbore radius controlled by the well, m; h _r is the reservoir thickness, m;

The gas column pressure is composed of the pressure of the original wellbore gas compressed by the killing fluid and the pressure of the continued intrusion gas. The calculation formula is as follows:

P _C ＝P _C1 +P _C2 (10)

In the formula: P _C1 and P _C2 are respectively the gas column pressure of the continuous flow effect and the gas column pressure generated by the original wellbore gas compression, MPa;

The calculation formula of the freewheeling effect gas column pressure is as follows:

The gas column pressure generated by compressing the gas in the original wellbore is ^[6] :

S24. Drawing the change law of the wellbore pressure in the well killing stage and analyzing the theoretical well killing curve, the specific steps are as follows:

After obtaining the formation physical properties, fluid parameters, and relevant data after shutting in the well, calculate the density of the killing fluid according to the formulas (1) and (2), and select the optimal displacement of the killing fluid according to the formulas (3) and (4). Formulas (6), (7) determine the relationship between wellhead pressure and wellbore pressure, combine with Table 1 to judge the pressure composition in the wellbore, calculate the relevant pressure by formulas (8), (9), and (10), and analyze according to the pressure composition in the wellbore The change law of wellbore pressure in each stage is drawn by drawing software to draw the wellbore pressure change curve.

S3. Process the data collected by the wellhead and bottomhole pressure sensors and draw the actual wellbore pressure change curve, which includes the following sub-steps:

S31, before the step S3, it also includes the step of killing the physical model, and the killing physical model includes the blowout preventer group 1 arranged on the top of the well, the signal receiver 2 arranged on the blowout preventer group 1, and the signal receiver The device 2 is electrically connected with the data processing system, the bottom of the well is provided with a bottom hole pressure sensor 3, and the top of the well is provided with a wellhead pressure sensor 4, and both the wellhead pressure sensor 4 and the bottom hole pressure sensor 3 are electrically connected with the signal receiver 2. The injector group 1 is provided with a drill pipe 5, the drill pipe 5 extends downwards in the well, and a drill bit 6 is installed at the extension end;

S32. Transmit the collected data to the data processing system through the signal receiver through the wellhead pressure sensor and the bottom hole pressure sensor;

S33. The data processing system performs cleaning and noise reduction preprocessing on the data;

S34. The data processing system analyzes the change law of the wellbore pressure in real time, and draws the actual wellbore pressure change curve;

S4. Analyze the theoretical wellbore pressure change curve and the actual wellbore pressure change curve, identify and judge the well killing stage: use the data analysis software to analyze the change law of the wellbore pressure data after processing and compare it with the change law of the theoretical wellbore pressure data. According to the similarity Distinguish the killing stage, which specifically includes the following steps: After the actual data is preprocessed, the data is regarded as a group. As the well killing progresses, the change rule between each group and the previous group of data is analyzed, and the theoretical data is compared with each group. The law of well stage change is compared and analyzed, and the change law with the highest degree of similarity is the actual well killing stage;

S5, as shown in Figure 2, the specific conditions for judging the end condition of well killing are that the overflow in the wellbore is completely pushed back to the formation and the hydrostatic column pressure in the wellbore meets the well control requirements, specifically including the following steps:

S51. According to step S4, it is judged whether to complete the push-back stage of the overflow, and the overflow includes gas and gas-liquid two-phase flow;

S52. Determine whether the hydrostatic column pressure meets the well control requirements at this time, that is, the hydrostatic column pressure in the wellbore has balanced the formation pressure and has a safety pressure of 3-5 MPa;

S53. If the above two conditions are met, the well killing can be ended.

The present invention calculates the wellbore pressure in each stage of well killing theoretically, and obtains the change law of wellbore pressure in each stage, and compares the change law of the measured data of well killing with the change law of wellbore pressure in the theoretical well killing stage, and obtains the actual well killing stage , based on the idea of reservoir protection, by judging the fluid composition and hydrostatic column pressure in the wellbore, a process for judging the termination conditions of well killing by direct push method is proposed, which can reduce the risk of reservoir pollution. The invention provides guarantee for the safety of the wellbore and formation in the well killing process through the accurate grasp of the well killing process, thereby providing theoretical guidance for the implementation of the well killing operation.

The above descriptions are only preferred embodiments of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and Modifications can be made within the scope of the ideas described herein, by virtue of the above teachings or skill or knowledge in the relevant art. However, changes and changes made by those skilled in the art do not depart from the spirit and scope of the present invention, and should all be within the protection scope of the appended claims of the present invention.

Claims (6)

1. A method for judging well killing stage and ending condition by a direct pushing method is characterized by comprising the following steps: it comprises the following steps:

s1, logging well shut-in data and stratum and fluid physical property parameters after well shut-in through geological logging data and adjacent well data;

s2, processing the data and parameters in the S1 and drawing a theoretical wellbore pressure change curve;

s3, processing the data acquired by the wellhead pressure sensor and the bottom pressure sensor and drawing an actual shaft pressure change curve;

s4, analyzing a theoretical shaft pressure change curve and an actual shaft pressure change curve, and identifying and judging a well killing stage;

and S5, judging the well killing end condition.

2. The method for determining the stage and the end condition of the straight-pushing well killing method according to claim 1, wherein the method comprises the following steps: the step S2 includes the following sub-steps:

s21, calculating the well killing discharge capacity and the well killing fluid density;

s22, determining the pressure composition relation in the well bore in the well killing process;

s23, calculating the pressure of the gas column;

s24, drawing a wellbore pressure change rule and theoretical kill curve analysis in the kill stage;

the method for determining the stage and the end condition of the straight-pushing well killing method according to claim 1, wherein the method comprises the following steps: the step S3 includes the following sub-steps:

s31, transmitting the acquired data to a data processing system through a signal receiver by a wellhead pressure sensor and a bottom hole pressure sensor;

s32, the data processing system carries out cleaning and noise reduction pretreatment on the data;

and S33, analyzing the change rule of the shaft pressure in real time by the data processing system, and drawing an actual shaft pressure change curve.

3. The method for determining the stage and the end condition of the straight-pushing well killing method according to claim 1, wherein the method comprises the following steps: and in the step S4, judging the well killing stage according to the similarity.

4. The method for determining the stage and the end condition of the straight-pushing well killing method according to claim 1, wherein the method comprises the following steps: the concrete conditions for judging the well killing end condition in the step S5 are that the overflow in the shaft is completely pushed back to the stratum and the hydrostatic column pressure in the shaft meets the well control requirement.

5. The method for determining the stage and the end condition of the straight-pushing well killing method according to claim 1, wherein the method comprises the following steps: the formation and fluid property parameters in the step S1 include formation pressure, rock porosity, permeability, pay thickness, gas density, gas viscosity, wellbore size, and formation pressure boundary; the well closing data after the well comprises a well body structure, a drilling tool assembly, well closing casing pressure, well closing vertical pressure, outlet density of drilling fluid, viscosity of drilling fluid, density of drilling fluid, fluid distribution in a shaft and fluid distribution in the shaft.

6. The method for determining the stage and the end condition of the straight-pushing well killing method according to claim 1, wherein the method comprises the following steps: still include the step of kill-job physical model before step S3, kill-job physical model is including setting up in blowout preventer stack (1) of roof, setting up in signal receiver (2) on blowout preventer stack (1), and signal receiver (2) are connected with the data processing system electricity, and the shaft bottom is provided with shaft bottom pressure sensor (3), and the roof is provided with well head pressure sensor (4), and well head pressure sensor (4) and shaft bottom pressure sensor (3) all are connected with signal receiver (2) electricity, be provided with drilling rod (5) in blowout preventer stack (1), drilling rod (5) extend in the well downwards, and extend the end department and install drill bit (6).