RU2421586C1 - Procedure for construction of horizontal well in devonian strata - Google Patents

Abstract

FIELD: oil and gas production. ^ SUBSTANCE: procedure for construction of horizontal well in Devonian strata consists in driving vertical section, section of initial curve with inclination angle built-up according to project, sections of inclination angle built-up coming to horizontal and in drilling horizontal borehole. To reduce probability of drilling tool freeze-in clay of Kynovsk horizon is driven at inclination angle entr less, than 60. Also, if inclination angle entr is 50-60, then a casing string is lowered into a borehole with entry into upper limestone and cemented. If inclination angle entr is 45-40 and less, than a borehole is cased with a casing string and cemented after there is reached a bottomhole of a well of the pay horizon by drilling according to a project profile. Actual value of inclination angle of entry into upper limestone on floor of Kynovsk horizon entr is determined with distance from upper limestone to a project oil reservoir A and radius of curve R at reaching curve in this interval to a required value according to formula: entr=arc sin (1-A/R), where entr is inclination angle of entry into upper limestone on floor of Kynovsk horizon, in degrees. A is a distance from upper limestone to a project oil reservoir, m, R is radius of drift angle build-up in the interval from upper limestone to a project oil reservoir, m, when value of A is reached at allowed value of intensity of curve for a given drill tool and casing string assembly. ^ EFFECT: reduced probability of drill tool freeze-in, reduced period of construction of well, reduced material expenditures. ^ 2 cl, 1 dwg, 1 ex

Description

The invention relates to the field of drilling directional and horizontal shafts of oil and gas wells on Devonian deposits, and in particular to methods of preventing erosion damage and the formation of caverns in the wellbore when drilling intervals of the Kynov horizon in a directional well.

A known method of drilling a horizontal well (see article "Features of the design of directional and horizontal wells with a large deviation from the vertical," magazine "Construction of oil and gas wells on land and at sea." M .: VNIIOENG, 1998, Issue 7, p. 6-9), including drilling a vertical section, a section of the initial curvature and drilling a design reservoir.

The disadvantage of this method is the impossibility of its use when drilling a well on a reservoir, composed of sandstones located directly under unstable rocks.

The disadvantages of this method are partially eliminated in the method of sinking a horizontal well (see the description of patent RU No. 2159318, IPC7 ЕВВ 7/06, publication date 11/20/2000), including sinking of a vertical section, a section of the initial curvature and drilling of a horizontal section, stabilization of the zenith angle is carried out up to the interval of stable rocks located below the bottom of the reservoir, and the zenith angle is up to 80 °, and the horizontal section is drilled to a length that provides after zenith angle more than 90 ° opening of the reservoir at the design point with subsequent sinking of the inclined or horizontal section in the reservoir.

It should be noted that in the description of this patent there are no recommendations for trouble-free drilling of clay rocks, in particular, the Kynovsky horizon when drilling horizontal wells on Devonian deposits.

There is also a method of drilling horizontal wells with a remote bottom hole (see the description of patent RU No. 2278939, IPC ЕВВ 7/04, published in BI No. 18, 06/27/2006).

The method includes sinking a vertical section, a section of initial curvature with a set of zenith angle according to the project, sections of a set of zenith angle with horizontal access and drilling a horizontal shaft.

The known method in technical essence is close to the proposed one and can be adopted as a prototype.

A common disadvantage of the methods according to patent No. 2159318 and adopted as a prototype is that they do not take into account a number of problems when drilling Kynovsky clay during the construction of horizontal wells on Devonian deposits, which is accompanied, as is known, by complications of the wellbore shedding, collapses and caverns, As a result, due to the collapse of the arch of the deviated wellbore, the annular channel is blocked by rock, hence the sticking of the drilling tool. Despite the large expenditures of time, labor and material resources associated with the study, his release is unsuccessful. In particular, the technology for the construction of inclined and horizontal wells according to well-known patents does not stipulate at what zenith angle the Kyn clay is exposed, the nature of the flow of drilling fluid in the annular channel, which drilling fluid is used in this case, since under the action of the drilling fluid, the barrel also breaks down wells as a result of deterioration of the mechanical properties of Kynovsky mudstones and also leading to sticking of the drill string. It is also not provided for the creation and control of the necessary load on the bit when drilling with a downhole screw motor with a large displacement of the faces from the wellhead for accelerated passage of Kyn clay.

The technical task of the present invention is to eliminate the likelihood of sticking a drilling tool during the sinking of the Kynovsky horizon, reducing the construction time of the well for Devonian deposits, as well as reducing material costs and labor.

The stated technical problem is solved by the described method, including the sinking of a vertical section, an initial curvature section with a set of zenith angle according to the project, a section of stabilization of the zenith angle, a section of a set of zenith angle with access to the horizontal and horizontal drilling.

What is new is that to reduce the likelihood of a tool sticking, the clay of the Kynovsky horizon passes at an zenith angle α _in less than 60 °, while if the zenith angle α _in is 50-60 °, then the casing is lowered into the well with the entrance to the upper limestone and cemented and if the inclination angle α is 45-40 ° _Bx and less then cased wellbore and cemented casing after the downhole drilling productive horizon in the project profile, and the specific value of the zenith angle of entry into the upper limestone soles kynovskogo horizon α _Rin determined distance from the top of limestone to project oil reservoir A and a curvature radius R of curvature at a set in this interval to its desired value according to the formula: α _Rin = arcsin (1-A / R),

where α _I - the zenith angle of entry into the upper limestone at the bottom of the Kynovsky horizon, in degrees,

A is the distance from the upper limestone to the design oil reservoir, m,

R is the radius of the set of curvature in the interval from the upper limestone to the design oil reservoir, m, ensuring the achievement of A at an acceptable value of the curvature intensity for a given assembly of drilling tools and casing, while to prevent caverning, the penetration of the Kynovsky horizon and below is carried out in the guaranteed laminar mode flows in the annular annular channel of a viscoplastic drilling fluid with fastening properties, and to accelerate the sinking of the Kyn clay, use the method creation and control of the required load on the bit when drilling directional and horizontal wells with a downhole motor with a large displacement of the faces from the wellhead, and for drilling intervals of stabilization of the zenith angle, a low-intensity increase or decrease is performed using a bitwise centralizer-stabilizer for drilling with downhole motors.

Preliminary patent research on the patent fund of the TatNIPIneft Institute with a retrospectiveness of 20 years to determine the technical level and the compliance with the criterion of "inventive step" showed that objects of similar purpose with such a set of distinctive features with a positive technical result were not found, which allows us to conclude compliance of the claimed object with the criterion of "novelty" and "inventive step".

The presented drawing explains the essence of the proposed method, schematically depicts a well drilled on Devonian deposits, where the interval of Kynovsky clays, upper limestone and the productive layer on the Devonian deposits are visible.

The method is as follows.

Horizontal wellbore drilling is carried out in accordance with the regulations for the construction of sidetracks, see RD 152-39.0-343-04, Bugulma, 2004. In accordance with this regulation, a 4-interval profile with the following sections is included in the fields of the Republic of Tatarstan: curvature (recession and set), stabilization (increase of 0.2-0.6% by 10 meters), the second set of zenith angle and horizontal section.

As the practice of constructing a horizontal well on the Devonian sediments has shown, the particular difficulty caused by the complication, in particular, shedding, cavern formation, collapse and sticking of the drilling tool, is the penetration of the Kynovsky horizon, the thickness of which is from 16 to 35 m, which is the cover of the oil deposits of the Pasha horizon and zhivsky layer of oil fields of Tatarstan. It is represented by lamellar shales (mudstones), which are classified as brittle rocks, are not subject to plastic deformation. The stamp hardness ranges from 0.4 to 0.8 kn / m ² [1], the Poisson's ratio "µ" is 0.10-0.22 [2, 3]. Since mudstones in the rock mass are in equilibrium under the influence of rock and pore pressures, when opening with drilling, the equilibrium is disturbed and stresses arise on the walls of the well. The latter are determined by the ratio of the interacting rock and pore pressures and the column pressure of the flushing fluid. If the stress exceeds the strength - the bearing capacity of the rocks, then the walls of the well instantly collapse, see also [2], hence the seizure of the drilling tool.

Caverns are mainly formed during the excavation of unstable clay rocks - clay shales of the Kynovsky, Pashiysky horizons as a result of surface, capillary and osmotic hydration of the mud filtrate, the strength characteristics of the Kynovsky clays in the near-barrel zone deteriorate [2]. Despite this, when drilling under these conditions in the interval of the Kyn horizon with flushing of the wellbore in the laminar regime, cavern flows do not form, and when flushing in turbulent mode, they form intensively. Over many years of drilling experience, it has been established that at zenith angles of α _in no more than 30-40 ° in the interval of Kynovsky clays, the latter do not complicate the deepening of the bottom of the well, the cuttings and lamellar-shaped pieces of mudstone from the walls of the wellbore are carried out by the flow of flushing fluid to the earth's surface. At a zenith angle α _in greater than 55 °, a drilling tool is grabbed during the deepening of the face in the Kyn horizon with washing of the barrel in turbulent mode [5, 6].

For example, when drilling horizontal well No. 24288 [4] for Devonian deposits, the tool was tacked during the drill string extension during the bottom hole of 1938 m after 140 hours from the start of drilling and penetration of 52.5 m along the Kynov horizon with a bit with a diameter of 215.9 mm at α = 67-69 ° from the bottom by washing clay and chalk solution (ρ _f = density 1220-1260 kg / m ^3, the relative viscosity of 60 s, O = 4.5-5.0 cm ^3/30 min, pH 8) at a flow rate 30-33 l / s. In the process of walking the drill tool, circulation was restored. When washing, many fragments of Kyn sludge came out. After that, oil with an emulsifier was pumped 3 times, but the drilling tool could not be released. A second trunk was drilled from a depth of 1661 m. The well was completed by drilling with a directional shaft.

In a horizontal well №20367 [4] in the washing process mud (density ρ _p = 1280 kg / m ^3, the relative viscosity of 30-38 s, O = 7 cm ^3/30 min, pH 8) at a rate of 30-33 l / from the bottom of 1922 m, the pressure suddenly increased in the discharge line of the rig, the safety diaphragm burst, and the drilling tool was seized. 25 m were passed along the Kynov horizon at α = 65 ° with a bit with a diameter of 215.9 mm, the time from the beginning of its opening to the grasp of the boring tool was 50 hours. Circulation was restored by walking the boring tool, but it was not possible to eliminate the stick. A second trunk was drilled from a depth of 1667 m. This well was also completed with directional drilling.

A similar case associated with the sticking of a drilling tool occurred in well No. 7199 [4] during rotary drilling with flushing of the bottom with a polymer clay solution at a rate of 10 l / s (density ρ _f = 1320 kg / m, nominal viscosity 30-38 s, Ф = 5.4 cm ^3/30 min). The BHA included a bit with a diameter of 125 mm, a centralizer with a diameter of 124 mm, a drill collar with a diameter of 108 mm and a length of 9 m, a centralizer with a diameter of 123 mm, a drill collar with a diameter of 108 mm and a length of 81 m, drill pipes. The seizure was accompanied by a sudden increase in pressure, the destruction of the safety diaphragm and loss of circulation. 25 meters were passed along the Kynov horizon at a zenith angle of 64 ° in 41 hours. The accident was eliminated by drilling the second wellbore, while the Kynov horizon was drilled at a 53 ° angle with flushing in a guaranteed laminar regime of drilling fluid flow in the annular channel of the well.

As can be seen from the above examples of rock drilling in wells No. 24288, 20367, 7199 for Devonian deposits, stresses arising in the wellbore led to the destruction of the borehole walls when the zenith angle exceeded 60 °, which corresponds to theoretical studies [2]. In particular, at zenith angles of 67-69 °, 65 ° and 64 °, respectively, a gripping of the drilling tool occurred. In wells No. 24288 and 20367, drilling to the design depth due to the lack of technology for drilling horizontal wells on the Devonian deposits, as noted above, was completed by the second wellbore with conventional drilling, i.e. with a small zenith angle, with a large investment of time, material and labor resources, in addition, this negatively affected the timely commissioning of the well on Devonian deposits.

The authors of the claimed technical solution by many years of field trials established the reasons [4] leading to a violation of the stability of the Kyn clay, in particular, these are:

1. Large anti-aircraft angle of the barrel.

2. Cavern formation by a turbulent flow of flushing fluid.

3. The softening of shale as a result of the action of the drilling fluid and the subsequent collapse of the arch of the horizontal trunk.

With the elimination of the identified causes, there was an attempt to drill a horizontal well No. 3704 for Devonian deposits. Drilling was performed under the horizon kynovskogo zenith angle of 67 ° with washing in laminar flow in the annular passage polymeric clay-free drilling fluid with a density of 1300 kg / m ^3, providing an osmotic drying kynovskih clays during autopsy, with fluid loss of 0.5 cm ^3/30 minutes dynamic shear stress 60-80 dPa. Despite this, after opening the Kynov horizon of 27 m at an antiaircraft angle of 67 °, the Kyn clays tumbled down and could not deepen the well further. It was decided to install a cement bridge in this well and open the Kyn horizon at an zenith angle of 55-57 ° with flushing with a guaranteed laminar flow in the annular channel with a clay-chalky drilling fluid with a density of 1280-1300 kg / m ³ with fixing properties. This plan was successfully implemented, Kynovsky horizon passed without an accident. After deepening the bottom by drilling a well into the upper limestone 1.5 m, it was cased with a 168 mm diameter casing and cemented. Further deepening of the well along the design profile was carried out with a bit with a diameter of 144 mm. This is the first horizontal Devonian sediment well drilled using new technology, i.e. the claimed method.

Thus, accident-free opening of the Kynov horizon with washing in a guaranteed laminar flow regime of a polymer-clay-chalk solution with a density of 1280-1300 kg / m ³ at an anti-aircraft angle of less than 60 ° was shown. In this case, the specific value of the zenith angle of entry into the upper limestone at the base of the Kynov horizon α _vx is determined by the distance from the upper limestone to the project oil reservoir A and the radius of curvature R when the curvature is set in this interval to its required value by the formula: α _bx = arcsin (1- A / R), where

α _I - the zenith angle of entry into the upper limestone or at the base of the Kynovsky horizon, in degrees,

A is the distance from the upper limestone to the design oil reservoir, m,

R is the radius of the set of curvature in the interval from the upper limestone to the design oil reservoir, m, ensuring the achievement of A with an acceptable value of the curvature intensity for a given arrangement of the drilling tool and casing.

If the zenith angle α _in , determined taking into account the values of A and R according to the above formula, is 50-60 °, then the casing is lowered into the well with the entrance to the upper limestone and cemented, and if the zenith angle α _in is 45-40 ° or less, then the well is cased with a casing string and cemented after reaching the bottom of the borehole of the productive horizon by drilling along the design profile, since, as noted above, even with the turbulent flow regime of drilling fluid, the drill string does not stick.

Tunneling of the Kynov horizon and below is carried out in the guaranteed laminar flow mode in the annular annular channel of a viscoplastic drilling fluid with fastening properties, with minimal water loss and the required density. To accelerate the sinking of Kyn clay and below, use the method of creating and controlling the required load on the bit when drilling directional and horizontal wells with a downhole motor with a large displacement of the faces from the wellhead, and for drilling intervals of stabilization of the zenith angle, a low-intensity increase or decrease is made using over-bit centralizer - stabilizer for drilling with downhole motors.

After casing with a casing string with a diameter of 168, 178 mm of drilled intervals, well drilling is continued along the design profile with a smaller bit diameter, starting from the shoe of the production string.

An example of a specific implementation of the method

The inventive method was built 19 horizontal wells on the Devonian deposits.

Below we give another example of drilling horizontal well No. 7336 for Devonian deposits with a casing run to the roof of a productive formation in the fields of OAO Tatneft. To draw up a well construction project using data from previously drilled neighboring wells, the interval of the Kynov horizon, as well as the upper limestone and the design oil reservoir of the well, were revealed. So, the roof of the Kynov horizon lies at a depth of 2028 m. The depth of the upper limestone is 2050 m, the thickness of which is 1.5-2.0 m. The vertical part of the well was drilled to a depth of 90 m using conventional technology. In the range of 110-310 m, an antiaircraft angle of 15 ° (14 ° 49 ') was gained. Further, the interval 310-1580 m was drilled with a direct layout with a decrease in the zenith angle to 3 ° 51 '. In the range of 1580-2020 m, the zenith angle α _in 42 ° 30 'was obtained, calculated using the above formula, with a curvature radius of R = 234 m and A = 78 m, which is the zenith angle of entry into the Kyn horizon. Prepared viscoplastic polimerglinisty chalk drilling fluid (washing liquid) using the method of preparation polimerglinistogo solution according to patent [7] with a density of 1280-1300 kg / m ^3, with filtrootdachey 5 cm ^3/30 min, with a conventional viscosity 46 s, with a plastic viscosity of 17 MPa · s, with a dynamic shear stress of 60-80 dPa.

Using this solution, the interval is 2020-2050 m, i.e. they reached the upper limestone with stabilization of the zenith angle of 42 ° 35 '. An interval of 2050-2215 m was drilled, having acquired a zenith angle of 81 °, after which the well was cased with a casing and cemented using cementing aggregates according to conventional technology. To prevent cavern formation, the drilling of the interval 2020-2215 was carried out in a guaranteed laminar flow regime in the annular annular channel using the invention of the patent [8], while to accelerate the sinking of Kyn clay and below, a method was used to create and control the load on the bit when drilling horizontal and inclined directed wells screw downhole motor with large displacements of the faces from the wellhead in accordance with the invention according to the patent [9]. And to provide drilling intervals for stabilization of the zenith angle, a low-intensity increase or decrease in it used the over-bit centralizer-stabilizer for drilling with downhole motors according to the invention according to the patent [10]. Thus, the combined use of the known aforementioned inventions with the claimed one ensured the penetration of the Kynovsky horizon without caverns in the wellbore and sticking of the drilling tool. Further, the well sinking, starting from the shoe of the production casing, was continued with a bit of smaller diameter f 144 mm. In the range of 2215-2305 m, an anti-aircraft angle of 90 ° was gained, drilled with a polymer clay drilling mud with a density of 1060 kg / m ³ . The interval of the horizontal section 2305-2450 m was drilled by reducing the zenith angle to 86 °, at which the design depth was reached, thus drilling a horizontal wellbore 235 m long along sandstones in a two-meter corridor. After washing the well and conducting geophysical studies, the open part of the wellbore, starting from the shoe of the production string, was cased with a filter with a diameter of 114 mm. After the inflow call, the well was put into operation with a flow rate of 100 tons / day.

The technical and economic advantage of the proposal is as follows.

Using the proposed method for the first time in the oil fields of the Republic of Tatarstan, 19 horizontal wells for Devonian deposits were built, which increased the production capabilities of horizontal wells by 2-3 or more times compared with the production capabilities of wells drilled for Devonian deposits vertically and with directional shafts, which ensured that OAO Tatneft received tangible economic benefits.

Information sources

1. Matveeva A.M. Mechanical properties of rocks of oil deposits of the Tatar Autonomous Soviet Socialist Republic. On Sat Mechanical properties of rocks during indentation and their practical use. - M.: VNIIOENG, 1966 .-- 130 s.

2. Rabinovich N.R. Engineering problems of continuum mechanics in drilling. - M .: Nedra, 1989 .-- 200 p.

3. Spivak A.I., Popov A.K. Rock destruction during well drilling. - M. Nedra, 1986.- 240 p.

4. Takhautdinov Sh.F., Bikchurin T.N. and others. "Research on the development of technology for opening the Kynovsky horizon at a large zenith angle," // Oil Economy. 2003, No. 3, p. 35-39.

5. The study of technical and technological factors determining the stability of the Kynovsky mudstones during well drilling. T.N. Bikchurin, I.G. Yusupov, R.S. Gabidullin and others // Oil industry. 2000, No. 12, p.25-27.

6. Bikchurin T.N., Kozlov F.A., Gabidullin R.S. "Technical progress in well construction." - Kazan: Tatknigoizdat, 1982. - 280 p.

7. RF patent No. 2231535 "Method for the preparation of polymer clay drilling mud."

8. RF patent No. 2256762 "Method for sinking unstable clay rocks while drilling oil and gas wells."

9. RF patent No. 2313667 “A method for creating and controlling the required load on a bit when drilling horizontal and directional wells with a downhole motor with large displacements of the faces from the wellhead”.

10. RF patent No. 2233962 "Over-bit centralizer-stabilizer for downhole motor drilling".

Claims (2)

1. A method of constructing a horizontal well for Devonian deposits, including sinking of a vertical section, an initial curvature section with a set of zenith angle according to the project, sections of a set of zenith angle with a horizontal outlet and horizontal drilling, characterized in that to reduce the likelihood of sticking a clay tool of the Kynovsky horizon tested under _Rin zenith angle α less than 60 °, while if the inclination angle α _Rin is 50-60 °, then the casing is lowered into the wellbore with the entrance to the upper th limestone and cement, and if the inclination angle α is 45-40 ° _Bx and less then cased wellbore and cemented casing after the downhole drilling productive horizon in the project profile, and the specific value of the zenith angle of entry into the upper limestone soles kynovskogo horizon α _I determine the distance from the upper limestone to the design oil reservoir A and the radius of curvature R when the set of curvature in this interval to its required value by the formula:
α _in = arcsin (1-A / R),
where α _in - the zenith angle of entry into the upper limestone at the bottom of the Kynovsky horizon, in degrees.
A is the distance from the upper limestone to the design oil reservoir, m
R is the radius of the set of curvature in the interval from the upper limestone to the design oil reservoir, m, ensuring the achievement of A with an acceptable value of the curvature intensity for this arrangement of the drilling tool and casing. 2. The method according to claim 1, characterized in that in order to prevent cavity formation, the penetration of the Kynovsky horizon is carried out in the guaranteed laminar flow mode in the annular annular channel of a viscoplastic drilling fluid with fastening properties, and to accelerate the penetration of Kynovsky clays, a method is used to create and control the necessary load on bit when drilling directional and horizontal wells with a downhole screw motor with a large displacement of the faces from the wellhead, and for drilling the interval low-intensity stabilization inclination angle increases or decreases it is produced using Near Bit centralizer - stabilizer for drilling downhole motors.

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