CN111691836A - Method for preventing collapse of mudstone in stone box - Google Patents
Method for preventing collapse of mudstone in stone box Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 44
- 239000004575 stone Substances 0.000 title claims abstract description 43
- 238000005553 drilling Methods 0.000 claims abstract description 135
- 239000012530 fluid Substances 0.000 claims abstract description 67
- 230000000694 effects Effects 0.000 claims abstract description 19
- 239000002002 slurry Substances 0.000 claims abstract description 8
- 239000007790 solid phase Substances 0.000 claims abstract description 8
- 239000011435 rock Substances 0.000 claims abstract description 7
- 239000004576 sand Substances 0.000 claims abstract description 5
- 239000003795 chemical substances by application Substances 0.000 claims description 21
- 238000006073 displacement reaction Methods 0.000 claims description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- 230000001133 acceleration Effects 0.000 claims description 6
- 239000000440 bentonite Substances 0.000 claims description 6
- 229910000278 bentonite Inorganic materials 0.000 claims description 6
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 claims description 6
- 230000002706 hydrostatic effect Effects 0.000 claims description 6
- 239000010445 mica Substances 0.000 claims description 6
- 229910052618 mica group Inorganic materials 0.000 claims description 6
- 239000000843 powder Substances 0.000 claims description 6
- 238000002360 preparation method Methods 0.000 claims description 6
- 238000007789 sealing Methods 0.000 claims description 6
- 230000005484 gravity Effects 0.000 claims description 4
- 239000004570 mortar (masonry) Substances 0.000 claims description 4
- 239000003292 glue Substances 0.000 claims description 3
- 239000002245 particle Substances 0.000 claims description 3
- 238000005086 pumping Methods 0.000 claims description 3
- 125000004122 cyclic group Chemical group 0.000 claims description 2
- 230000002265 prevention Effects 0.000 abstract description 11
- 238000010276 construction Methods 0.000 abstract description 10
- 239000009096 changqing Substances 0.000 abstract description 7
- 239000003208 petroleum Substances 0.000 abstract description 3
- 239000004568 cement Substances 0.000 description 6
- 244000144730 Amygdalus persica Species 0.000 description 2
- 235000006040 Prunus persica var persica Nutrition 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/42—Compositions for cementing, e.g. for cementing casings into boreholes; Compositions for plugging, e.g. for killing wells
- C09K8/46—Compositions for cementing, e.g. for cementing casings into boreholes; Compositions for plugging, e.g. for killing wells containing inorganic binders, e.g. Portland cement
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
- E21B21/06—Arrangements for treating drilling fluids outside the borehole
- E21B21/063—Arrangements for treating drilling fluids outside the borehole by separating components
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
- E21B21/08—Controlling or monitoring pressure or flow of drilling fluid, e.g. automatic filling of boreholes, automatic control of bottom pressure
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/10—Sealing or packing boreholes or wells in the borehole
- E21B33/13—Methods or devices for cementing, for plugging holes, crevices or the like
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Abstract
The invention relates to the technical field of petroleum drilling, in particular to a method for preventing collapse of mudstone in a stone box, which is characterized in that the inner diameter of a cylinder sleeve of a slurry pump is changed on the premise that rock debris can return out of the ground along with well drilling fluid, so that the discharge capacity is reduced, the annular return speed is reduced, and the annular pressure loss is reduced; when the discharge capacity is reduced and the leakage speed is less than 1-3 square/hour, stopping leakage while drilling when the discharge capacity is reduced by 50-100 meters before the leakage layer is drilled; and (3) time control drilling after opening a leaking layer: controlling the mechanical drilling speed, wherein the pure drilling time of each drilling is not less than 30 minutes, and simultaneously starting the sand and mud remover all-in-one machine and the centrifugal machine to remove harmful solid phases in the drilling fluid; the method is suitable for the stratum wells of 8 and 1 meshes in the boxes and the mountains in the Su-Li-Ge area of the Changqing oil field, the collapse prevention construction of the mudstone boxes is achieved, and the collapse prevention effect is good.
Description
Technical Field
The invention relates to the technical field of petroleum drilling, in particular to a method for preventing collapse of mudstone in a stone box.
Background
In the drilling construction process of horizontal wells of the box 8 and the mountain 1 target layer in the Su-Li-Ge area of the Changqing oil field, the mudstone section of the stone box is long, the well is inclined greatly and is easy to collapse; the Liujia ditch stratum has low pressure bearing capacity, the density of the drilling fluid cannot reach the minimum density required by balanced mudstone, and the drilling fluid leaks upwards and collapses downwards to cause underground complex frequent outbreak. Such as: the construction of the peach 2-8-30H1 and the peach 2-8-30H1 wells for well leakage and mudstone collapse is not successful for 2 times, the density of the Sudong wells 20-25H1 and the Sudong wells 26-29H2 cannot reach the balanced formation pressure due to well leakage, the mudstone collapses after water is produced, and the loss time is 1016 hours. The method starts from the aspect of pressure-bearing leakage stoppage in the earlier stage, improves the density of the drilling fluid by improving the pressure-bearing capacity of the stratum to physically prevent the collapse of the stone box mudstone, and has little effect. The main influencing factors are as follows:
1) the mudstone is easy to collapse. The mudstone has high carbonization degree, poor plasticity, good development, obvious transverse bedding structure, weak hydration degree and poor chemical anti-collapse effect, belongs to brittle cracked rock, and is mainly maintained to be stable in the aspect of mechanics.
2) And in the process of improving the density of the drilling fluid, the leakage of the Liujia ditch generally exists in the box 8 and the mountain 1 target layer horizontal well. The well leakage velocity completed in the early stage is more than 10m3H is used as the reference value. The mudstone of the multiple wells collapses and is forced to fill the well and sidetrack.
After the well lost returns and lost by 20-25H1 Sudong, the smooth drill rod is lowered to the bottom of the Liujia ditch and is cemented by 12m3Closing the well and co-extruding into 8.6m3The highest pressure of cement paste is gradually increased from 3.5MPa to 4.2MPa after each time of squeezing, but the highest pressure is reduced to 0 after 25min, which indicates that the Liujia ditch stratum is not bearing pressure, and the squeezing condition is shown in a Sudong 20-25H1 well squeezing cement squeezing condition chart shown in figure 1.
3) The mudstone section is long and the well deviation is large.
The stone box mudstone is an overburden layer of a development target layer, the section length is 15-80m, and the target layer is formed after the stone box is drilled through, so that the mudstone well deflection is large (80-84 degrees), and the collapse stress is increased.
Disclosure of Invention
The invention overcomes the defects of the prior art, provides a method for preventing collapse of stone box mudstone, and is particularly suitable for the 8-mesh and 1-mesh layer wells of boxes in Su-Li-Ge areas of Changqing oil fields, and the collapse prevention of the stone box mudstone.
The technical problem solved by the invention can be realized by adopting the following technical scheme:
a method for preventing collapse of mudstone in stone box comprises the following steps
S001: on the premise that the rock debris can return out of the ground along with well fluid, the inner diameter of a cylinder sleeve of the slurry pump is changed, the discharge capacity is reduced, the annular space return speed is reduced, and the annular space pressure loss is reduced;
s002: when the discharge capacity is reduced and the leakage speed is less than 1-3 square/hour, stopping leakage while drilling when the discharge capacity is reduced by 50-100 meters before the leakage layer is drilled;
s003: and (3) time control drilling after opening a leaking layer: controlling the mechanical drilling speed, wherein the pure drilling time of each drilling is not less than 30 minutes, and simultaneously starting the sand and mud remover all-in-one machine and the centrifugal machine to remove harmful solid phases in the drilling fluid;
s004: optimizing the well track on the basis of the step S002, and controlling the mudstone section well deviation: during leak stoppage while drilling, the vertical depth of a target point is reduced according to the vertical depth of the drilling target point and the vertical depth of mudstone, the mudstone is windowed from the middle lower part of the gas layer, the mudstone inclination angle is reduced, the maximum inclination is smaller than 74 degrees, and the mudstone collapse pressure is reduced;
s005: when the drill is pulled out after opening the mudstone, the alternating stress measures are reduced: compensate annular circulation pressure loss, avoid suction to form negative pressure, the system of filling a mortar is put into effect, prevent the drilling string and the wall of a well collision.
And in the step S001, the inner diameter of the mud pump cylinder sleeve is changed from 180mm or 170mm to 160mm or 150mm, the discharge capacity is reduced from 34L/S to 26-30L/S, the annulus return speed is reduced from 1.51m/S to 1.33m/S, the annulus pressure loss is reduced, and the annulus pressure loss is reduced from 1.19Mpa to 0.95 Mpa.
The displacement is reduced from 34L/s to 29L/s.
The formula of the plugging agent for plugging while drilling in the step S002, the preparation method and the method for plugging while drilling are as follows:
(1) according to the mass percentage, 1-2% of bentonite powder, 1-1.5% of mica, 1% of one-way pressure plugging agent DF-A, 1% of sawdust and the balance of water are mixed and stirred evenly at normal temperature and normal pressure;
(2) and then adding the plugging agent in the step (1) into the drilling fluid before entering a leaking layer, forming a pressure difference by using the plugging agent in the step (1) and fine solid-phase particles in the drilling fluid, and entering the leaking layer to plug a leakage passage close to the wellbore under the action of the pressure difference to plug the microcracks so as to improve the pressure-bearing capacity of the stratum.
The formula and the preparation method of the plugging agent for plugging while drilling in the step S002 are as follows:
according to the mass percentage, 1.5 percent of bentonite powder, 1.25 percent of mica, 1 percent of one-way pressure plugging agent DF-A, 1 percent of sawdust and the balance of water are mixed and stirred evenly at normal temperature and normal pressure.
The method for compensating the cyclic pressure loss in the step S005 comprises the following steps:
when a stone box mudstone is opened to start drilling, the hydrostatic column pressure (P well bottom) is controlled to be balanced, the annular pressure loss (P ring) is calculated, the amount and the density of the weighted drilling fluid are calculated according to the hydrostatic column pressure P well bottom which is 32MPa + P ring, the weighted drilling fluid is prepared to compensate annular pressure loss, and the mudstone is prevented from collapsing in an empty well state;
before opening the stone box and pulling out the mudstone, according to the formula rho ═ rho0+PRing (C)The calculated and desired weighted drilling fluid density of/g.H, where ρ: the required weighted drilling fluid density; rho0: the density of the original drilling fluid; pRing (C): annular circulation pressure loss; h: the drilling is vertical and deep; g: and (3) pumping the drilling fluid into a well section above the mudstone by adopting a displacement of 18-20L/s under the action of gravity acceleration, circulating the weighted drilling fluid out in a segmented manner by adopting a displacement of 18-20L/s during the drilling, starting an integrated machine and a centrifugal machine to reduce the weighted drilling fluid to the original density, or adopting a diluted and supplemented glue solution to control the density and viscosity of the drilling fluid before the shaft and the ground drilling fluid are pulled out.
The value of the gravitational acceleration g is 0.00981.
The method for implementing the grouting system in the step S005 comprises the following steps:
grouting the annular space when opening the stone box mudstone to start drilling, filling drilling fluid into the annular space by 3 columns of each drill rod, and filling drilling fluid into the annular space by 1 column of each drill collar;
when the stone box is opened, filling the drilling fluid into every 20 columns once when the mudstone is drilled, and circulating the drilling fluid for 1 time every 1000 meters;
and secondly, filling the drilling fluid at a distance of 30 meters from the bottom of the well, connecting the kelly bar to cut the hole to the bottom of the well, and recovering normal drilling after circulating for one week.
In step S005, in order to avoid negative pressure from being formed by suction, the speed is controlled at 3-5 minutes per column when the drill is tripped, so as to reduce the suction effect, which can reduce the pressure of the fluid column to cause well collapse, and meanwhile, the single pressure plugging agent must be kept under the positive pressure to normally perform the sealing effect, and if negative pressure is caused, the sealing is relieved, and leakage occurs again.
The method for preventing the drill string from colliding with the well wall in the step S005 comprises the following steps:
(5) long-time fixed-point circulation in a mudstone well section is avoided;
(6) strictly controlling the tripping speed of the mudstone-making well section, wherein the speed range is controlled to be 3-5 minutes per upright post;
(7) after the mudstone is opened, the rotating speed of the turntable is controlled to be 40-50 rpm;
(8) and the sliding drilling in the mudstone section is reduced.
The invention has the beneficial effects that:
compared with the prior art, the method effectively prevents collapse of the stone box mudstone and improves the construction efficiency, wherein the method is suitable for the 8-mesh layer well and the 1-mesh layer well of the box in the Su-Li-Ge area of the Changqing oil field, and the collapse prevention construction of the stone box mudstone has good collapse prevention effect.
Drawings
The invention is further illustrated with reference to the following figures and examples.
FIG. 1 is a schematic representation of the present invention of a Sudong 20-25H1 well squeeze.
Fig. 2 is a schematic view of the lower target access window of the present invention.
In the figure: 1. mud rock; 2. and (4) a gas layer.
Detailed Description
Example 1:
a method for preventing collapse of mudstone in stone box comprises the following steps
S001: on the premise that the rock debris can return out of the ground along with well fluid, the inner diameter of a cylinder sleeve of the slurry pump is changed, the discharge capacity is reduced, the annular space return speed is reduced, and the annular space pressure loss is reduced;
s002: when the discharge capacity is reduced and the leakage speed is less than 1-3 square/hour, stopping leakage while drilling when the discharge capacity is reduced by 50-100 meters before the leakage layer is drilled;
s003: and (3) time control drilling after opening a leaking layer: controlling the mechanical drilling speed, wherein the pure drilling time of each drilling is not less than 30 minutes, and simultaneously starting the sand and mud remover all-in-one machine and the centrifugal machine to remove harmful solid phases in the drilling fluid;
s004: optimizing the well track on the basis of the step S002, and controlling the mudstone section well deviation: during leak stoppage while drilling, the vertical depth of a target point is reduced according to the vertical depth of the drilling target point and the vertical depth of the mudstone 1, the mudstone is windowed from the middle lower part of the gas layer 2, the mudstone inclination angle is reduced, the maximum inclination is smaller than 74 degrees, and the mudstone collapse pressure is reduced;
s005: when the drill is pulled out after opening the mudstone, the alternating stress measures are reduced: compensate annular circulation pressure loss, avoid suction to form negative pressure, the system of filling a mortar is put into effect, prevent the drilling string and the wall of a well collision.
By the aid of the method, collapse prevention of the stone box mudstone is effectively prevented, construction efficiency is improved, the method is suitable for stratum wells of 8-mesh and 1-mesh boxes in Su-Li-Ge areas of Changqing oil fields, collapse prevention construction of the stone box mudstone is achieved, and collapse prevention effect is good.
Example 2:
a method for preventing collapse of mudstone in stone box comprises the following steps
S001: on the premise that rock debris can return out of the ground while drilling well fluid, the inner diameter of a cylinder sleeve of the slurry pump is changed from 180mm or 170mm to 160mm or 150mm, the discharge capacity is reduced from 34L/s to 26-30L/s, the annular return speed is reduced from 1.51m/s to 1.33m/s, the annular pressure loss is reduced, and the annular pressure loss is reduced from 1.19Mpa to 0.95 Mpa;
the displacement is reduced from 34L/s to 29L/s;
s002: when the discharge capacity is reduced and the leakage speed is less than 1-3 square/hour, stopping leakage while drilling when the discharge capacity is reduced by 50-100 meters before the leakage layer is drilled;
the formula of the plugging agent for plugging while drilling, the preparation method and the plugging method while drilling are as follows:
(1) according to the mass percentage, 1-2% of bentonite powder, 1-1.5% of mica, 1% of one-way pressure plugging agent DF-A, 1% of sawdust and the balance of water are mixed and stirred evenly at normal temperature and normal pressure;
(2) then adding the plugging agent in the step (1) into the drilling fluid before entering a leaking layer, forming a pressure difference by using the plugging agent in the step (1) and fine solid-phase particles in the drilling fluid, and entering the leaking layer to plug a leakage passage close to a well casing to plug a microcrack under the action of the pressure difference, so that the pressure-bearing capacity of a stratum is improved;
the formula and the preparation method of the plugging agent for plugging while drilling comprise the following steps:
according to the mass percentage, 1.5 percent of bentonite powder, 1.25 percent of mica, 1 percent of one-way pressure plugging agent DF-A, 1 percent of sawdust and the balance of water are mixed and stirred evenly at normal temperature and normal pressure;
s003: and (3) time control drilling after opening a leaking layer: controlling the mechanical drilling speed, wherein the pure drilling time of each drilling is not less than 30 minutes, and simultaneously starting the sand and mud remover all-in-one machine and the centrifugal machine to remove harmful solid phases in the drilling fluid;
s004: optimizing the well track on the basis of the step S002, and controlling the mudstone section well deviation: during leak stoppage while drilling, the vertical depth of a target point is reduced according to the vertical depth of the drilling target point and the vertical depth of mudstone, the mudstone is windowed from the middle lower part of the gas layer, the mudstone inclination angle is reduced, the maximum inclination is smaller than 74 degrees, and the mudstone collapse pressure is reduced;
s005: when the drill is pulled out after opening the mudstone, the alternating stress measures are reduced: compensate annular circulation pressure loss, avoid suction to form negative pressure, the system of filling a mortar is put into effect, prevent the drilling string and the wall of a well collision.
The method for compensating the circulating pressure loss comprises the following steps:
when a stone box mudstone is opened to start drilling, the hydrostatic column pressure (P well bottom) is controlled to be balanced, the annular pressure loss (P ring) is calculated, the amount and the density of the weighted drilling fluid are calculated according to the hydrostatic column pressure P well bottom which is 32MPa + P ring, the weighted drilling fluid is prepared to compensate annular pressure loss, and the mudstone is prevented from collapsing in an empty well state;
before opening the stone box and pulling out the mudstone, according to the formula rho ═ rho0+PRing (C)The calculated and desired weighted drilling fluid density of/g.H, where ρ: the required weighted drilling fluid density; rho0: the density of the original drilling fluid; pRing (C): annular circulation pressure loss; h: the drilling is vertical and deep; g: pumping the mud into the well section above the mudstone by adopting the displacement of 18-20L/s under the action of gravity acceleration, and setting the mud in the well section above the mudstone by adopting the displacement of 18-E20L/s of weighted drilling fluid is circulated in a segmented mode, the integrated machine and the centrifuge are started to reduce the weighted drilling fluid to the original density, or the diluted and supplemented glue solution is adopted to control the density and the viscosity of the drilling fluid before the shaft and the ground drilling fluid are pulled out;
the value of the gravity acceleration g is 0.00981;
the method for implementing the grouting system comprises the following steps:
grouting the annular space when opening the stone box mudstone to start drilling, filling drilling fluid into the annular space by 3 columns of each drill rod, and filling drilling fluid into the annular space by 1 column of each drill collar; the stone box stratum is located in 3200-3500, 3000 meters of drilling tools are arranged in the well when the stone box stratum is opened, and 3 columns of each drilling rod and 1 column of each drill collar are values specified in the technical specification;
when the stone box is opened, filling the drilling fluid into every 20 columns once when the mudstone is drilled, and circulating the drilling fluid for 1 time every 1000 meters;
secondly, filling the drilling fluid at a distance of 30 meters from the bottom of the well, connecting a kelly bar to cut the hole to the bottom of the well, and recovering normal drilling after circulating for one week;
in the step S005, in order to avoid negative pressure formed by suction, the speed is controlled to be 3-5 minutes per column when the drill is pulled out so as to reduce the suction effect, the suction effect can reduce the liquid column pressure to cause well collapse, meanwhile, the single pressure plugging agent can normally play a sealing effect only by keeping the positive pressure, and if negative pressure is caused, the sealing is released, and leakage occurs again;
the method for preventing the drill string from colliding with the well wall comprises the following steps:
(9) long-time fixed-point circulation in a mudstone well section is avoided;
(10) strictly controlling the tripping speed of the mudstone-making well section, wherein the speed range is controlled to be 3-5 minutes per upright post;
(11) after the mudstone is opened, the rotating speed of the turntable is controlled to be 40-50 rpm;
and the sliding drilling in the mudstone section is reduced.
By the method, the collapse prevention construction of the stone box mudstone is suitable for the 8-mesh layer well and the 1-mesh layer well of the box in the Su-Li-Ge area of the Changqing oil field, and the collapse prevention effect is good.
Example 3:
referring to fig. 1, the schematic diagram of the cement squeezing and injecting condition of the Sudong 20-25H1 well is shown, wherein the Sudong 20-25H1 well squeezes 2.5 square of cement slurry in 25 minutes for the first time, the highest pressure bearing capacity of the stratum is 3.5MPa, the cement slurry squeezes 1.2 square in 25 minutes for the second time, the pressure bearing capacity of the stratum reaches 4 MPa, the cement slurry squeezes 0.5 square in the third time, the pressure bearing capacity of the stratum reaches 4.2MPa, the higher the pressure bearing capacity of the stratum is, the higher the density of the drilling fluid is favorably improved, and the better.
Fig. 2 is a schematic view of window entry of the underground target area of the east Su 20-25H1, and it can be known from the figure that the maximum angle of inclination alpha of mudstone entering the window from the middle lower part of the gas layer is obviously smaller than the maximum angle of inclination beta of mudstone entering the window from the upper part of the gas layer, and the well section of the mudstone is shortened.
The average gas layer thickness of horizontal wells of the block box 8 and the mountain 1 target layer is 10-12m, the construction wells enter the windows 3-4m after entering the gas layer in the early stage, and the maximum mudstone inclination angle exceeds 80 degrees. By lowering the vertical depth of the target point and entering the window from 8-9m into the gas layer, the maximum angle of the mudstone well can be controlled within 75 degrees. The corresponding relation between the target vertical depth and the maximum mudstone inclination angle is shown in table 1.
Table 1: relation between target vertical depth and maximum mudstone well inclination angle
| Depth into air layer (m) | 3.5 | 4.5 | 5.5 | 6.5 | 7.5 | 8.5 |
| Mudstone section well inclination (°) | 80.36 | 78.85 | 77.54 | 74.34 | 75.24 | 74.21 |
The invention effectively solves the problem of mudstone collapse in the petroleum drilling process, can obtain good effect in field application, effectively reduces the complex condition of lost circulation, reduces the production time and saves the drilling cost.
Compared with the traditional method, the invention has the following technical indexes:
the average drilling period in 2019 is shortened by 11.56 days, the average well construction period is shortened by 9.74 days, the average mechanical drilling speed is improved by 9.54 percent, the monthly speed of a drilling machine is improved by 22.16 percent, the well leakage is greatly reduced, and complex faults such as drill sticking, well collapse and the like do not occur, which is shown in table 2.
Table 2: compared with the technical scheme of the traditional method, the invention has the advantages that the indexes are compared
Through the comparison, the collapse prevention effect of the stone box mudstone is good for the box 8 and the mountain 1-purpose layer well in the Su Li Ge area of the Changqing oil field after the method is applied, and the method can be popularized and used.
While the embodiments of the present invention have been described in detail with reference to the drawings, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art, and the scope of the present invention is within the scope of the claims.
It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.
Technical solutions between various embodiments may be combined with each other, but must be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
Claims (10)
1. A method for preventing collapse of mudstone in a stone box is characterized by comprising the following steps: comprises the following steps
S001: on the premise that the rock debris can return out of the ground along with well fluid, the inner diameter of a cylinder sleeve of the slurry pump is changed, the discharge capacity is reduced, the annular space return speed is reduced, and the annular space pressure loss is reduced;
s002: when the discharge capacity is reduced and the leakage speed is less than 1-3 square/hour, stopping leakage while drilling when the discharge capacity is reduced by 50-100 meters before the leakage layer is drilled;
s003: and (3) time control drilling after opening a leaking layer: controlling the mechanical drilling speed, wherein the pure drilling time of each drilling is not less than 30 minutes, and simultaneously starting the sand and mud remover all-in-one machine and the centrifugal machine to remove harmful solid phases in the drilling fluid;
s004: optimizing the well track on the basis of the step S002, and controlling the mudstone section well deviation: during leak stoppage while drilling, the vertical depth of a target point is reduced according to the vertical depth of the drilling target point and the vertical depth of mudstone, the mudstone is windowed from the middle lower part of the gas layer, the mudstone inclination angle is reduced, the maximum inclination is smaller than 74 degrees, and the mudstone collapse pressure is reduced;
s005: when the drill is pulled out after opening the mudstone, the alternating stress measures are reduced: compensate annular circulation pressure loss, avoid suction to form negative pressure, the system of filling a mortar is put into effect, prevent the drilling string and the wall of a well collision.
2. The method of preventing collapse of stone box mudstone as claimed in claim 1, wherein: and in the step S001, the inner diameter of the mud pump cylinder sleeve is changed from 180mm or 170mm to 160mm or 150mm, the discharge capacity is reduced from 34L/S to 26-30L/S, the annulus return speed is reduced from 1.51m/S to 1.33m/S, the annulus pressure loss is reduced, and the annulus pressure loss is reduced from 1.19Mpa to 0.95 Mpa.
3. A method of preventing collapse of stone box mudstone as claimed in claim 2, wherein: the displacement is reduced from 34L/s to 29L/s.
4. The method of preventing collapse of stone box mudstone as claimed in claim 1, wherein: the formula of the plugging agent for plugging while drilling in the step S002, the preparation method and the method for plugging while drilling are as follows:
(1) according to the mass percentage, 1-2% of bentonite powder, 1-1.5% of mica, 1% of one-way pressure plugging agent DF-A, 1% of sawdust and the balance of water are mixed and stirred evenly at normal temperature and normal pressure;
(2) and then adding the plugging agent in the step (1) into the drilling fluid before entering a leaking layer, forming a pressure difference by using the plugging agent in the step (1) and fine solid-phase particles in the drilling fluid, and entering the leaking layer to plug a leakage passage close to the wellbore under the action of the pressure difference to plug the microcracks so as to improve the pressure-bearing capacity of the stratum.
5. The method of preventing collapse of stone box mudstone as claimed in claim 4, wherein: the formula and the preparation method of the plugging agent for plugging while drilling in the step S002 are as follows:
according to the mass percentage, 1.5 percent of bentonite powder, 1.25 percent of mica, 1 percent of one-way pressure plugging agent DF-A, 1 percent of sawdust and the balance of water are mixed and stirred evenly at normal temperature and normal pressure.
6. The method of preventing collapse of stone box mudstone as claimed in claim 1, wherein: the method for compensating the cyclic pressure loss in the step S005 comprises the following steps:
when a stone box mudstone is opened to start drilling, the hydrostatic column pressure (P well bottom) is controlled to be balanced, the annular pressure loss (P ring) is calculated, the amount and the density of the weighted drilling fluid are calculated according to the hydrostatic column pressure P well bottom which is 32MPa + P ring, the weighted drilling fluid is prepared to compensate annular pressure loss, and the mudstone is prevented from collapsing in an empty well state;
before opening the stone box and pulling out the mudstone, according to the formula rho ═ rho0+PRing (C)The calculated and desired weighted drilling fluid density of/g.H, where ρ: the required weighted drilling fluid density; rho0: the density of the original drilling fluid; pRing (C): annular circulation pressure loss; h: the drilling is vertical and deep; g: and (3) pumping the drilling fluid into a well section above the mudstone by adopting a displacement of 18-20L/s under the action of gravity acceleration, circulating the weighted drilling fluid out in a segmented manner by adopting a displacement of 18-20L/s during the drilling, starting an integrated machine and a centrifugal machine to reduce the weighted drilling fluid to the original density, or adopting a diluted and supplemented glue solution to control the density and viscosity of the drilling fluid before the shaft and the ground drilling fluid are pulled out.
7. The method of preventing collapse of stone box mudstone as claimed in claim 6, wherein: the value of the gravitational acceleration g is 0.00981.
8. The method of preventing collapse of stone box mudstone as claimed in claim 1, wherein: the method for implementing the grouting system in the step S005 comprises the following steps:
grouting the annular space when opening the stone box mudstone to start drilling, filling drilling fluid into the annular space by 3 columns of each drill rod, and filling drilling fluid into the annular space by 1 column of each drill collar;
when the stone box is opened, filling the drilling fluid into every 20 columns once when the mudstone is drilled, and circulating the drilling fluid for 1 time every 1000 meters;
and secondly, filling the drilling fluid at a distance of 30 meters from the bottom of the well, connecting the kelly bar to cut the hole to the bottom of the well, and recovering normal drilling after circulating for one week.
9. The method of preventing collapse of stone box mudstone as claimed in claim 1, wherein: in step S005, in order to avoid negative pressure from being formed by suction, the speed is controlled at 3-5 minutes per column when the drill is tripped, so as to reduce the suction effect, which can reduce the pressure of the fluid column to cause well collapse, and meanwhile, the single pressure plugging agent must be kept under the positive pressure to normally perform the sealing effect, and if negative pressure is caused, the sealing is relieved, and leakage occurs again.
10. The method of preventing collapse of stone box mudstone as claimed in claim 1, wherein: the method for preventing the drill string from colliding with the well wall in the step S005 comprises the following steps:
(1) long-time fixed-point circulation in a mudstone well section is avoided;
(2) strictly controlling the tripping speed of the mudstone-making well section, wherein the speed range is controlled to be 3-5 minutes per upright post;
(3) after the mudstone is opened, the rotating speed of the turntable is controlled to be 40-50 rpm;
(4) and the sliding drilling in the mudstone section is reduced.
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Application publication date: 20200922 |