CN114135250B - Sand control method and device for casing change well - Google Patents
Sand control method and device for casing change well Download PDFInfo
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- CN114135250B CN114135250B CN202010923231.5A CN202010923231A CN114135250B CN 114135250 B CN114135250 B CN 114135250B CN 202010923231 A CN202010923231 A CN 202010923231A CN 114135250 B CN114135250 B CN 114135250B
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
- E21B33/14—Methods or devices for cementing, for plugging holes, crevices, or the like for cementing casings into boreholes
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/02—Subsoil filtering
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/10—Geothermal energy
Abstract
The application provides a method and a device for sand prevention of a casing change well, and belongs to the technical field of oil extraction engineering. The technical scheme comprises the following steps: after the position of a target stratum to be sand-protected is determined, the height of a sand plug to be molded is obtained based on the pressure difference between the upper part and the lower part of the stratum, the preset volume of precoated sand required for forming the corresponding sand plug is obtained according to the height, and when the pressure of the target stratum rises suddenly in the subsequent process of injecting a mixture formed by sand-carrying fluid and precoated sand into a casing, the precoated sand which is injected into a well can be determined to be just enough for forming an artificial well wall, the precoated sand is continuously injected, and the volume of the precoated sand injected afterwards is obtained in real time so as to reach the preset volume, thereby the precoated sand which is injected into the well can just form the artificial well wall and the sand plug with the height corresponding to the stratum pressure, the sand plug does not influence the liquid of an oil layer, can protect a damaged casing, and prevent sand from entering the well bore from the broken part of the casing, and thus the sand-preventing effect can be continuously played in the subsequent production process.
Description
Technical Field
The application relates to the technical field of oil extraction engineering, in particular to a method and a device for sand prevention of a casing change well.
Background
In the oil extraction process, original sand and stones in the stratum can flow out of the stratum along with crude oil, and along with the duration of the oil extraction process, sand and stones in the stratum are less and less, so that formation deficiency, sleeve deformation and even the condition of oil well production stopping can possibly occur, sand prevention measures are needed to be taken for preventing the occurrence of the phenomenon, and the sand production of the stratum is slowed down.
The currently common sand control methods include: and (3) conveying the precoated sand into the well by adopting sand-carrying liquid, and forming a layer of artificial well wall in the stratum after the precoated sand is solidified. However, when the mode is used for sand control construction of the sleeve variable well, the artificial well wall cannot protect the damaged sleeve due to serious sleeve deformation, after sand control construction is completed and production is continued, the sleeve deformation can be aggravated, so that sand control failure is caused, the sand control effective period is short, and the sand control effect is poor.
Disclosure of Invention
The embodiment of the application provides a method and a device for sand prevention of a casing-changing well, which can form a sand plug in a casing, and the sand plug can be used for protecting a damaged casing and preventing sand from entering a shaft from a broken part of the casing so as to continuously play a role in sand prevention in a subsequent production process. The technical scheme is as follows:
in one aspect, a method of sand control for a casing string is provided, the method comprising:
sand washing is carried out on the oil well until an artificial well bottom or a sleeve change position is reached, and a stratum corresponding to the artificial well bottom or the sleeve change position is a target stratum;
acquiring the height of a sand plug to be formed based on the pressure difference of the upper part and the lower part of the target stratum;
based on the height of the sand plug, acquiring a preset volume of precoated sand required for forming the sand plug;
using a well logging gauge to log well logging;
adjusting the sleeve above the target stratum to ensure that the tightness of the sleeve meets the preset requirement;
uniformly injecting a mixture of sand-carrying fluid and precoated sand into the sleeve, wherein the mixture has a first sand-carrying ratio;
measuring the pressure of the target stratum in real time, when the change rate of the pressure of the target stratum along with time is larger than the preset change rate, marking the moment as a first moment, and reducing the sand carrying ratio of the first mixture to be a second sand carrying ratio;
acquiring the volume of precoated sand injected into the casing from the first moment in real time;
when the volume is equal to the preset volume, reducing the sand carrying ratio of the mixture to zero;
after the mixture replaces the oil outlet pipe with the precoated sand remained in the casing, closing the well and waiting for solidification for preset time, so that the precoated sand forms an artificial well bottom in the target stratum, and the precoated sand forms a sand plug with preset height in the casing.
In one possible implementation, the obtaining the height of the sand plug to be formed based on the pressure difference above and below the target formation includes:
the height is obtained based on the following relation 1:
l= (K. DELTA.P. A)/(Q. Mu.) relation 1
Wherein: l is the height of the sand plug, m;
k-absolute permeability, m 2 ；
Δp—pressure difference across the target formation, pa;
a-inner cross-sectional area of sleeve, m 2 ；
Q-flow velocity of fluid, m 3 /s；
Mu-viscosity of liquid, pa.s.
In one possible implementation, the obtaining a preset volume of precoated sand required to form the sand plug based on the height of the sand plug includes:
the preset volume is obtained based on the following relation 2:
relation 2
Wherein: v-volume of sand plug, m 3 ；
d Pipe The inner diameter of the oil pipe, m;
l is the height of the sand plug, m.
In one possible implementation, the acquiring in real time the volume of precoated sand injected into the casing from the first moment comprises:
the volume of the precoated sand was obtained based on the following relation 3:
relation 3
Wherein: v (V) t -volume, m, of precoated sand injected into the casing from the first moment 3 ；
Q t -a time-dependent relationship of the flow rate of the fluid;
S sand and sand -a time-dependent relation of sand ratio of the fluid;
t-time, s.
In one possible implementation, before sand washing the well, the method further comprises:
and obtaining the usage amount of precoated sand required by sand control construction according to the following relation 4:
V sand and sand =π·R 2 ·H·φ＋V Sand washing + V Sand discharge ＋V Attached with Relation 4
V Sand and sand The dosage of precoated sand, m, required by sand control construction 3 ；
R is the expected treatment radius of sand prevention, m;
h, the effective thickness of the target stratum, m;
phi-target formation porosity,%;
V sand washing The sum of sand flushing amount of oil well operation in the past year, m 3 ；
V Sand discharge The sum of sand removal amount along with produced fluid in the production process of the oil well, m 3 ；
V Attached with -preset added value of amount, m 3 。
In one possible implementation manner, after the closing waiting for the preset period of time, the method further includes:
detecting the height of a sand plug formed by condensation in the sleeve by adopting a sand detection plug;
and when the height exceeds the preset height, the screw drill is adopted to punch the sand plug drill to the preset height.
In one aspect, a set of well control sand control devices is provided, the device comprising:
the sand washing module is used for washing sand of the oil well until reaching the artificial well bottom or the sleeve position, and the stratum corresponding to the artificial well bottom or the sleeve position is the target stratum;
the height acquisition module is used for acquiring the height of the sand plug to be formed based on the pressure difference of the upper part and the lower part of the target stratum;
the preset volume acquisition module is used for acquiring the preset volume of precoated sand required by the sand plug based on the height of the sand plug;
the well dredging module is used for dredging wells by using the well dredging gauge;
the adjusting module is used for adjusting the sleeve above the target stratum to ensure that the tightness of the sleeve meets the preset requirement;
the injection module is used for uniformly injecting a mixture of sand-carrying fluid and precoated sand into the casing, and the mixture has a first sand-carrying ratio;
the measuring module is used for measuring the pressure of the target stratum in real time, when the change rate of the pressure of the target stratum along with time is larger than the preset change rate, marking the moment as a first moment, and reducing the sand carrying ratio of the first mixture to be a second sand carrying ratio;
the acquisition module is used for acquiring the volume of the precoated sand injected into the casing from the first moment in real time;
the injection module is also used for reducing the sand carrying ratio of the mixture to zero when the volume is equal to the preset volume;
and the timing module is used for closing the well and waiting for coagulation for a preset time period after the mixture replaces the residual precoated sand in the casing pipe with the oil outlet pipe, so that the precoated sand forms an artificial well bottom in the target stratum, and the precoated sand forms a sand plug with a preset height in the casing pipe.
In one possible implementation, the obtaining the height of the sand plug to be formed based on the pressure difference above and below the target formation includes:
the height is obtained based on the following relation 1:
l= (K. DELTA.P. A)/(Q. Mu.) relation 1
Wherein: l is the height of the sand plug, m;
k-absolute permeability, m 2 ；
Δp—pressure difference across the target formation, pa;
a-inner cross-sectional area of sleeve, m 2 ；
Q-flow velocity of fluid, m 3 /s；
Mu-viscosity of liquid, pa.s.
In one possible implementation, the obtaining a preset volume of precoated sand required to form the sand plug based on the height of the sand plug includes:
the preset volume is obtained based on the following relation 2:
relation 2
Wherein: v-volume of sand plug, m 3 ；
d Pipe The inner diameter of the oil pipe, m;
l is the height of the sand plug, m.
In one possible implementation, the acquiring in real time the volume of precoated sand injected into the casing from the first moment comprises:
the volume of the precoated sand was obtained based on the following relation 3:
relation 3
Wherein: v (V) t -the volume of precoated sand injected into the casing from the first moment，m 3 ；
Q t -a time-dependent relationship of the flow rate of the fluid;
S sand and sand -a time-dependent relation of sand ratio of the fluid;
t-time, s.
According to the technical scheme provided by the embodiment of the application, after the position of the target stratum to be sand-preventing is determined, the height of the sand plug to be molded is obtained based on the pressure difference between the upper and lower sides of the stratum, the preset volume of the precoated sand required for forming the corresponding sand plug is obtained according to the height, and when the pressure of the target stratum rises in the process of injecting the mixture formed by the sand-carrying fluid and the precoated sand into the casing in the follow-up process, the precoated sand which is injected into the well can be determined to be just enough for forming an artificial well wall, the precoated sand is continuously injected, and the volume of the precoated sand injected afterwards is obtained in real time, so that the preset volume is reached, the precoated sand which is injected into the well can be just formed into the artificial well wall and the sand plug with the height corresponding to the stratum pressure, the sand plug does not influence the oil layer liquid, the broken casing can be protected, sand and sand can be prevented from entering the well from the broken casing in the follow-up process, and thus the sand-preventing effect can be continuously played in the follow-up production process.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for sand control in a casing string according to an embodiment of the present application;
FIG. 2 is a flow chart of a method for sand control in a casing string according to an embodiment of the present application;
FIG. 3 is a schematic diagram of a well casing according to an embodiment of the present application;
FIG. 4 is a schematic diagram of construction parameters of a casing string sand control according to an embodiment of the present application;
FIG. 5 is a schematic diagram of a set of well control devices according to an embodiment of the present application;
fig. 6 is a schematic structural diagram of a computer device according to an embodiment of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present application more apparent, the embodiments of the present application will be described in further detail with reference to the accompanying drawings.
FIG. 1 is a flowchart of a method for sand control in a casing string, according to an embodiment of the present application, referring to FIG. 1, the method may be applied to a computer device, and the method includes:
101. and (3) sand washing is carried out on the oil well until the artificial well bottom or the sleeve position is reached, wherein the stratum corresponding to the artificial well bottom or the sleeve position is the target stratum.
102. And acquiring the height of the sand plug to be formed based on the pressure difference of the upper part and the lower part of the target stratum.
103. Based on the height of the sand plug, a preset volume of precoated sand required to form the sand plug is obtained.
104. And (5) using a well logging tool to log well logging.
105. And adjusting the sleeve above the target stratum to ensure that the tightness of the sleeve meets the preset requirement.
106. And uniformly injecting a mixture of sand-carrying fluid and precoated sand into the sleeve, wherein the mixture has a first sand-carrying ratio.
107. And measuring the pressure of the target stratum in real time, and when the change rate of the pressure of the target stratum along with time is larger than the preset change rate, marking the time as a first time, and reducing the sand carrying ratio of the first mixture to be a second sand carrying ratio.
108. And acquiring the volume of precoated sand injected into the casing from the first moment in real time.
109. And when the volume is equal to the preset volume, reducing the sand carrying ratio of the mixture to zero.
110. After the mixture replaces the oil outlet pipe with the precoated sand remained in the casing, closing the well and waiting for solidification for preset time, so that the precoated sand forms an artificial well bottom in the target stratum, and the precoated sand forms a sand plug with preset height in the casing.
According to the method provided by the embodiment of the application, after the position of the target stratum to be sand-preventing is determined, the height of the sand plug to be molded is obtained based on the pressure difference between the upper and lower sides of the stratum, the preset volume of the precoated sand required for forming the corresponding sand plug is obtained according to the height, and in the process of injecting the mixture formed by the sand-carrying fluid and the precoated sand into the casing in the subsequent process, when the pressure of the target stratum rises, the precoated sand which is injected into the well can be determined to be just enough for forming an artificial well wall, the precoated sand is continuously injected, and the volume of the precoated sand injected afterwards is obtained in real time, so that the preset volume is reached, the precoated sand which is injected into the well can just form the artificial well wall and the sand plug with the height corresponding to the stratum pressure, the sand plug does not influence the oil layer to be discharged, the damaged casing can be protected, sand and sand can be prevented from entering the well shaft from the broken part of the casing, and thus the sand-preventing effect can be continuously played in the subsequent production process.
In one possible implementation, the obtaining the height of the sand plug to be formed based on the pressure difference above and below the target formation includes:
the height is obtained based on the following relation 1:
l= (K. DELTA.P. A)/(Q. Mu.) relation 1
Wherein: l is the height of the sand plug, m;
k-absolute permeability, m 2 ；
Δp—pressure difference across the target formation, pa;
a-inner cross-sectional area of sleeve, m 2 ；
Q-flow velocity of fluid, m 3 /s；
Mu-viscosity of liquid, pa.s.
In one possible implementation, the obtaining a preset volume of precoated sand required to form the sand plug based on the height of the sand plug includes:
the preset volume is obtained based on the following relation 2:
relation 2
Wherein: v-volume of sand plug, m 3 ；
d Pipe The inner diameter of the oil pipe, m;
l is the height of the sand plug, m.
In one possible implementation, the acquiring in real time the volume of precoated sand injected into the casing from the first moment comprises:
the volume of the precoated sand was obtained based on the following relation 3:
relation 3
Wherein: v (V) t -volume, m, of precoated sand injected into the casing from the first moment 3 ；
Q t -a time-dependent relationship of the flow rate of the fluid;
S sand and sand -a time-dependent relation of sand ratio of the fluid;
t-time, s.
In one possible implementation, before sand washing the well, the method further comprises:
and obtaining the usage amount of precoated sand required by sand control construction according to the following relation 4:
V sand and sand =π·R 2 ·H·φ＋V Sand washing + V Sand discharge ＋V Attached with Relation 4
V Sand and sand The dosage of precoated sand, m, required by sand control construction 3 ；
R is the expected treatment radius of sand prevention, m;
h, the effective thickness of the target stratum, m;
phi-target formation porosity,%;
V sand washing The sum of sand flushing amount of oil well operation in the past year, m 3 ；
V Sand discharge The sum of sand removal amount along with produced fluid in the production process of the oil well, m 3 ；
V Attached with ——Preset added value of quantity, m 3 。
In one possible implementation manner, after the closing waiting for the preset period of time, the method further includes:
detecting the height of a sand plug formed by condensation in the sleeve by adopting a sand detection plug;
and when the height exceeds the preset height, the screw drill is adopted to punch the sand plug drill to the preset height.
FIG. 2 is a flow chart of a method for sand control in a casing string, as shown in FIG. 2, according to an embodiment of the present application, the method may be applied to a computer device, and the method includes:
201. and obtaining the usage amount of precoated sand required by sand control construction.
In this step, the amount of precoated sand obtained is used to facilitate the operator's preparation of a sufficient amount of precoated sand for construction. The precoated sand is double-component sand formed by uniformly coating a layer of resin and a curing agent on the surface of quartz sand with a certain particle size, or sand formed by directly coating a layer of resin film on the quartz sand. When sand prevention is performed, the precoated sand is uniformly stirred by the sand mixing vehicle, then is pumped into a stratum by carrying sand-carrying fluid, and under the action of the conditions of stratum temperature, pressure and the like, resin on the outer surface of the resin sand and solidified sand act or the precoated sand directly acts with the sand-carrying fluid, so that contacted particles are mutually bonded and gradually solidified, and an artificial well wall with high strength and good permeability is formed.
Sand-carrying fluid refers to fluid used to carry solids such as sand, proppants, etc. into the formation. In the petroleum exploitation process, crude oil is extracted from the stratum, and liquid left after petroleum is extracted from the crude oil can be used as sand-carrying fluid, so that the stratum is not changed or damaged when sand-carrying fluid is used for bringing solids such as sand, propping agent and the like into the stratum.
In one possible implementation, the amount of precoated sand required for sand control construction is obtained according to the following relation 4:
V sand and sand =π·R 2 ·H·φ＋V Sand washing + V Sand discharge ＋V Attached with Relation 4
V Sand and sand The usage amount of precoated sand required by sand prevention construction，m 3 ；
R is the expected treatment radius of sand prevention, m;
h, the effective thickness of the target stratum, m;
phi-target formation porosity,%;
V sand washing The sum of sand flushing amount of oil well operation in the past year, m 3 ；
V Sand discharge The sum of sand removal amount along with produced fluid in the production process of the oil well, m 3 ；
V Attached with -preset added value of amount, m 3 。
202. And (3) sand washing is carried out on the oil well until the artificial well bottom or the sleeve position is reached, wherein the stratum corresponding to the artificial well bottom or the sleeve position is the target stratum.
The sand washing means that liquid is pumped into the well through an oil sleeve annulus and then flows back to the well through an oil pipe, so that the liquid can carry sand and stone remained in an oil outlet channel to the well in the oil extraction process. The sleeve deformation refers to sleeve deformation, if the deformation degree of the sleeve is large, sand flushing can be continued until the artificial bottom of the well by replacing a sand flushing pipe between the small sand flushing pipes, and correspondingly, the corresponding position of the artificial bottom of the well can be set as a target stratum; if the deformation of the sleeve is smaller, sand cannot be continuously washed to the position below the deformation position of the sleeve, correspondingly, the stratum corresponding to the sleeve change point can be used as the target stratum, and correspondingly, the stratum section below the sleeve change point is the closed section.
203. And acquiring the height of the sand plug to be formed based on the pressure difference of the upper part and the lower part of the target stratum.
Fig. 3 is a schematic structural diagram of a casing string according to an embodiment of the present application, referring to fig. 3, various related structures of a bottom hole are shown, including: the device comprises a casing, an oil pipe, an annulus between the casing and the oil pipe, a target stratum, an artificial well wall formed by precoated sand in the target stratum, a sand plug formed by the precoated sand in the casing, a height L of the sand plug, a sleeve change point and a closed section. In this step, the higher the reserved sand plug, the stronger the ability to protect the casing, and the poorer the permeability, so that it is necessary to protect the casing without affecting the reservoir drainage. Since the sand plug has only one medium, the fluid passing through can also be considered a fluid, and can therefore be calculated by the absolute permeability relationship. The absolute permeability of a rock is the permeability measured when only one fluid is present in the pores of the rock, the fluid does not react with the rock physically and chemically, and the flow of the fluid complies with darcy's law of linear seepage.
In one possible implementation, the height is obtained based on the following relation 1:
l= (K. DELTA.P. A)/(Q. Mu.) relation 1
Wherein: l is the height of the sand plug, m;
k-absolute permeability, m 2 ；
Δp—pressure difference across the target formation, pa;
a-inner cross-sectional area of sleeve, m 2 ；
Q-flow velocity of fluid, m 3 /s；
Mu-viscosity of liquid, pa.s.
In the above relation 1, K is the permeability of the coated sand after consolidation, which can be obtained by an indoor experiment, and in this embodiment, the coated sand used is a flood coated sand, which has been found to be 20-40 μm by an experiment 2 The value of the obtained product is 30 mu m for convenient calculation 2 ；
The delta P can be obtained through stratum pressure test, and also can be obtained through calculation of a dynamic liquid face value and wellhead casing pressure;
a is the internal sectional area of the sleeve, and the internal diameter d of the conventional sleeve Cover For 124.26mm, the relationship can be calculated from the area: a=pi·d Cover 2 And/4, calculating.
Q can be obtained through conversion of daily liquid production of the oil well.
μ can be obtained from crude oil analysis assay data for each fragment.
204. Based on the height of the sand plug, a preset volume of precoated sand required to form the sand plug is obtained.
In this step, the preset volume is used to guide the subsequent sand plug forming process.
In one possible implementation, the obtaining a preset volume of precoated sand required to form the sand plug based on the height of the sand plug includes:
the preset volume is obtained based on the following relation 2:
relation 2
Wherein: v-volume of sand plug, m 3 ；
d Oil (oil) The inner diameter of the oil pipe, m;
l is the height of the sand plug, m.
In relation 2, the inner diameter d of the oil pipe is generally used Oil (oil) 62mm; the height L of the sand plug is obtained by step 203 described above.
205. And (5) using a well logging tool to log well logging.
In this implementation, this step may be: the well is cleared to a position above the oil layer by using a D114mm well clearance gauge.
206. And adjusting the sleeve above the target stratum to ensure that the tightness of the sleeve meets the preset requirement.
In this implementation, this step may be: the lower packer tests the pressure of 15.0MPa on the casing above the target stratum, and tests the pressure of 20MPa on the oil pipe, and the pressure drop is smaller than 0.5MPa after 30min, so that the pressure drop is qualified; if the test is not qualified, the necessary measures are taken to adjust until the test is qualified.
207. And uniformly injecting a mixture of sand-carrying fluid and precoated sand into the sleeve, wherein the mixture has a first sand-carrying ratio.
In this implementation, this step may be: and (3) lifting out the pressure test pipe column, and lowering the sand control pipe column to a position 10 meters above the target stratum, and installing a 350-model wellhead device at the top of the oil well according to the precoated sand control construction procedure.
(1) Pressure test of pipeline: connecting a pipeline, testing the pressure to 25.0MPa, and ensuring that 1min is not pricked or leaked, so as to show that the pressure is qualified;
(2) Flushing: adopting sand-carrying fluid, flushing the well to the outlet for returning fluid, and closing a sleeve gate after sleeve water returns;
(3) And (3) trial extrusion: test squeezing sand-carrying liquid 10m into oil well 3 Observing the change of pressure displacement, keeping the displacement to be more than 800L/min and the pressure to be lower than 20.0MPa;
(4) Adding sand: and uniformly adding a mixture of precoated sand with the model of 0.4-0.8mm and sand-carrying fluid, and controlling the first sand carrying ratio to be about 5-10%, wherein if the pressure is stable or is reduced, the first sand carrying ratio is gradually increased to 15% after half of the designed sand is added.
208. And measuring the pressure of the target stratum in real time, and when the change rate of the pressure of the target stratum along with time is larger than the preset change rate, marking the time as a first time, and reducing the sand carrying ratio of the first mixture to be a second sand carrying ratio.
In this step, the sand ratio is immediately reduced to avoid too much precoat sand being added too quickly into the wellbore when the pressure jump indicates that the targeted formation is full of sand. Specifically, the preset change rate may be preset according to actual conditions, or may be determined according to images of an operation site. For example, fig. 4 is a schematic diagram of construction parameters of sand control for a casing string according to an embodiment of the present application, please refer to a pressure surge line in fig. 4, a time corresponding to the pressure surge line may be marked as a first time, and the sand carrying ratio may be reduced to a second sand carrying ratio, that is, 10% in fig. 4.
209. And acquiring the volume of precoated sand injected into the casing from the first moment in real time.
In one possible implementation, the volume of the precoated sand is obtained based on the following relation 3:
relation 3
Wherein: v (V) t -volume, m, of precoated sand injected into the casing from the first moment 3 ；
Q t -a time-dependent relationship of the flow rate of the fluid;
S sand and sand -a time-dependent relation of sand ratio of the fluid;
t-time, s.
In the above-mentioned relation 3, the following formula,time-dependent relation Q of flow velocity of fluid t The relation S of the sand ratio of the fluid over time may be a constant value, a preset relation, or a relation generated in real time according to the change of the actual flow rate Sand and sand The relation may be a preset relation or a relation generated in real time according to a change in the actual flow rate, and this embodiment is not limited thereto.
210. And when the volume is equal to the preset volume, reducing the sand carrying ratio of the mixture to zero.
In the step, the sand carrying ratio of the mixture is reduced to zero, namely, only the sand carrying fluid in the mixture is free of the precoated sand, and the sand carrying fluid input into the oil well is used for displacing the residual precoated sand in the oil pipe, so that only the precoated sand for forming the sand plug is left.
211. And after the mixture replaces the residual precoated sand in the casing pipe with the oil outlet pipe, closing the well and waiting for solidification for a preset period of time.
The preset time period can be preset according to experience, for example, the diffusion pressure of closing the well is firstly 1-2 hours, and then closing the well is waited for 48 hours, so that the artificial well wall is completely cemented and has certain strength.
212. And detecting the height of the sand plug formed by condensation in the sleeve by adopting the sand plug.
The position of the sand plug is shown with continued reference to fig. 3.
213. And when the height exceeds the preset height, the screw drill is adopted to punch the sand plug drill to the preset height.
The preset height corresponds to a target stratum which is used as a production interval, so that the precoated sand forms an artificial bottom hole in the target stratum, and in the step, the precoated sand forms a sand plug with the preset height in the casing.
Any combination of the above optional solutions may be adopted to form an optional embodiment of the present application, which is not described herein.
According to the method provided by the embodiment of the application, after the position of the target stratum to be sand-preventing is determined, the height of the sand plug to be molded is obtained based on the pressure difference between the upper and lower sides of the stratum, the preset volume of the precoated sand required for forming the corresponding sand plug is obtained according to the height, and in the process of injecting the mixture formed by the sand-carrying fluid and the precoated sand into the casing in the subsequent process, when the pressure of the target stratum rises, the precoated sand which is injected into the well can be determined to be just enough for forming an artificial well wall, the precoated sand is continuously injected, and the volume of the precoated sand injected afterwards is obtained in real time, so that the preset volume is reached, the precoated sand which is injected into the well can just form the artificial well wall and the sand plug with the height corresponding to the stratum pressure, the sand plug does not influence the oil layer to be discharged, the damaged casing can be protected, sand and sand can be prevented from entering the well shaft from the broken part of the casing, and thus the sand-preventing effect can be continuously played in the subsequent production process.
Fig. 5 is a schematic structural diagram of a device for sand control in a casing string according to an embodiment of the present application, please refer to fig. 5, the device includes:
the sand washing module 501 is used for washing sand of the oil well until an artificial bottom hole or a sleeve position is reached, wherein a stratum corresponding to the artificial bottom hole or the sleeve position is a target stratum;
the height obtaining module 502 is configured to obtain a height of the sand plug to be formed based on a pressure difference between the upper and lower sides of the target stratum;
a preset volume obtaining module 503, configured to obtain a preset volume of precoated sand required for forming the sand plug based on the height of the sand plug;
a well logging module 504 for logging well logging using a logging tool;
the adjusting module 505 is configured to adjust a casing above the target stratum, so that the tightness of the casing meets a preset requirement;
an injection module 506, configured to uniformly inject a mixture of sand-carrying fluid and precoated sand into the casing, where the mixture has a first sand-carrying ratio;
the measurement module 507 is configured to measure, in real time, the pressure of the target formation, and when the rate of change of the pressure of the target formation with time is greater than a preset rate of change, mark the time as a first time, and reduce the sand carrying ratio of the first mixture to a second sand carrying ratio;
an acquisition module 508, configured to acquire, in real time, a volume of precoated sand injected into the casing from a first moment;
the injection module 506 is further configured to reduce the sand carrying ratio of the mixture to zero when the volume is equal to a preset volume;
and the timing module 509 is used for closing the well and waiting for a preset time period after the mixture replaces the residual precoated sand in the casing with the oil outlet pipe, so that the precoated sand forms an artificial bottom hole in the target stratum, and the precoated sand forms a sand plug with a preset height in the casing.
In one possible implementation, the obtaining the height of the sand plug to be formed based on the pressure difference above and below the target formation includes:
the height is obtained based on the following relation 1:
l= (K. DELTA.P. A)/(Q. Mu.) relation 1
Wherein: l is the height of the sand plug, m;
k-absolute permeability, m 2 ；
Δp—pressure difference across the target formation, pa;
a-inner cross-sectional area of sleeve, m 2 ；
Q-flow velocity of fluid, m 3 /s；
Mu-viscosity of liquid, pa.s.
In one possible implementation, the obtaining a preset volume of precoated sand required to form the sand plug based on the height of the sand plug includes:
the preset volume is obtained based on the following relation 2:
relation 2
Wherein: v-volume of sand plug, m 3 ；
d Pipe The inner diameter of the oil pipe, m;
l is the height of the sand plug, m.
In one possible implementation, the acquiring in real time the volume of precoated sand injected into the casing from the first moment comprises:
the volume of the precoated sand was obtained based on the following relation 3:
relation 3
Wherein: v (V) t -volume, m, of precoated sand injected into the casing from the first moment 3 ；
Q t -a time-dependent relationship of the flow rate of the fluid;
S sand and sand -a time-dependent relation of sand ratio of the fluid;
t-time, s.
It should be noted that: when the casing-changing well sand control device provided in the above embodiment is used for casing-changing well sand control, only the division of the functional modules is used for illustration, in practical application, the above-mentioned functional allocation can be completed by different functional modules according to the needs, that is, the internal structure of the device is divided into different functional modules so as to complete all or part of the functions described above. In addition, the apparatus for casing-changing well sand prevention and the method embodiment for casing-changing well sand prevention provided in the above embodiments belong to the same concept, and specific implementation processes thereof are detailed in the method embodiment, and are not described herein again.
According to the device provided by the embodiment of the application, after the position of the target stratum to be sand-preventing is determined, the height of the sand plug to be molded is obtained based on the pressure difference between the upper part and the lower part of the stratum, the preset volume of the precoated sand required for forming the corresponding sand plug is obtained according to the height, and in the process of injecting the mixture formed by the sand-carrying fluid and the precoated sand into the casing in the follow-up process, when the pressure of the target stratum rises, the precoated sand which is injected into the well can be determined to be just enough for forming an artificial well wall, the precoated sand is continuously injected, and the volume of the precoated sand injected afterwards is obtained in real time, so that the preset volume is reached, the precoated sand which is injected into the well can be just formed into the artificial well wall and the sand plug with the height corresponding to the stratum pressure, the sand plug does not influence the oil layer to be discharged, the damaged casing can be protected, sand and sand can be prevented from entering the well from the casing crack.
Fig. 6 is a schematic structural diagram of a computer device according to an embodiment of the present application, where the computer device 600 may have a relatively large difference due to different configurations or performances, and may include one or more processors (central processing units, CPU) 601 and one or more memories 602, where at least one program code is stored in the memories 602, and the at least one program code is loaded and executed by the processors 601 to implement the methods provided in the respective method embodiments. Of course, the computer device may also have a wired or wireless network interface, a keyboard, an input/output interface, and other components for implementing the functions of the device, which are not described herein.
In an exemplary embodiment, a computer readable storage medium, e.g. a memory comprising program code, executable by a processor in a terminal to perform the resource retrieval method of the above embodiment, is also provided. For example, the computer readable storage medium may be Read-Only Memory (ROM), random-access Memory (Random Access Memory, RAM), compact disc Read-Only Memory (CD-ROM), magnetic tape, floppy disk, optical data storage device, and the like.
It will be understood by those skilled in the art that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by program code related hardware, where the above program may be stored in a computer readable storage medium, and the above storage medium may be a read only memory, a magnetic disk or an optical disk, etc.
The foregoing description of the preferred embodiments of the present application is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements within the spirit and principles of the present application.
Claims (6)
1. A method of sand control for a casing string, the method comprising:
sand washing is carried out on the oil well until an artificial well bottom or a sleeve change position is reached, wherein a stratum corresponding to the artificial well bottom or the sleeve change position is a target stratum;
acquiring the height of a sand plug to be formed based on the pressure difference between the upper and lower parts of the target stratum;
acquiring a preset volume of precoated sand required for forming the sand plug based on the height of the sand plug;
using a well logging gauge to log well logging;
adjusting the sleeve above the target stratum to ensure that the tightness of the sleeve meets the preset requirement;
uniformly injecting a mixture of sand-carrying fluid and precoated sand into the sleeve, wherein the mixture has a first sand-carrying ratio;
measuring the pressure of the target stratum in real time, and when the change rate of the pressure of the target stratum along with time is larger than a preset change rate, marking the time as a first time, and reducing the sand carrying ratio of the mixture to be a second sand carrying ratio;
acquiring the volume of precoated sand injected into the casing from the first moment in real time;
when the volume is equal to the preset volume, reducing the sand carrying ratio of the mixture to zero;
after the mixture replaces the residual precoated sand in the casing pipe with the oil outlet pipe, closing the well and waiting for solidification for a preset time period, so that the precoated sand forms an artificial well bottom in the target stratum, and the precoated sand forms a sand plug with a preset height in the casing pipe;
after the shut-in waiting for the preset time period, the method further comprises the following steps:
detecting the height of a sand plug formed by condensation in the sleeve by adopting a sand detection plug;
and when the height exceeds the preset height, the screw drill is adopted to punch the sand plug drill to the preset height.
2. The method of claim 1, wherein the obtaining a height of a sand plug to be formed based on a pressure differential across the target formation comprises:
the height of the sand plug is obtained based on the following relation 1:
l= (K. DELTA.P. A)/(Q. Mu.) relation 1
Wherein: l is the height of the sand plug, m;
k-absolute permeability, m 2 ；
Δp—pressure difference across the target formation, pa;
a-inner cross-sectional area of sleeve, m 2 ；
Q-flow velocity of fluid, m 3 /s；
Mu-viscosity of liquid, pa.s.
3. The method of claim 1, wherein the obtaining a preset volume of precoated sand required to form the sand plug based on the height of the sand plug comprises:
the preset volume of the precoated sand is obtained based on the following relation 2:
relation 2
Wherein: v-volume of sand plug, m 3 ；
d Pipe -oil pipe inner diameter, m;
l is the height of the sand plug, m.
4. The method of claim 1, wherein the acquiring in real time the volume of precoated sand injected into the casing from the first moment comprises:
and (3) acquiring the volume of the precoated sand based on the following relation 3:
relation 3
Wherein: v (V) t -volume, m, of precoated sand injected into the casing from the first moment 3 ；
Q t -a time-dependent relationship of the flow rate of the fluid;
S sand and sand -a time-dependent relation of sand ratio of the fluid;
t-time, s.
5. The method of claim 1, wherein prior to flushing the well, the method further comprises:
and obtaining the usage amount of precoated sand required by sand control construction according to the following relation 4:
V sand and sand =π·R 2 ·H·φ＋V Sand washing + V Sand discharge ＋V Attached with Relation 4
V Sand and sand The dosage of precoated sand, m, required by sand control construction 3 ；
R is the expected treatment radius of sand prevention, m;
h, the effective thickness of the target stratum, m;
phi-target formation porosity,%;
V sand washing The sum of sand flushing amount of oil well operation in the past year, m 3 ；
V Sand discharge The sum of sand removal amount along with produced fluid in the production process of the oil well, m 3 ；
V Attached with -preset added value of amount, m 3 。
6. A casing-shifting well sand control device for performing the method of any of claims 1-5, the device comprising:
the sand washing module is used for washing sand of the oil well until reaching the position of the artificial bottom hole or the sleeve position, wherein the stratum corresponding to the artificial bottom hole or the sleeve position is the target stratum;
the height acquisition module is used for acquiring the height of the sand plug to be formed based on the pressure difference of the upper part and the lower part of the target stratum;
the preset volume acquisition module is used for acquiring the preset volume of precoated sand required by the sand plug based on the height of the sand plug;
the well dredging module is used for dredging wells by using the well dredging gauge;
the adjusting module is used for adjusting the sleeve above the target stratum to enable the tightness of the sleeve to meet the preset requirement;
the injection module is used for uniformly injecting a mixture of sand-carrying fluid and precoated sand into the casing, and the mixture has a first sand-carrying ratio;
the measuring module is used for measuring the pressure of the target stratum in real time, when the change rate of the pressure of the target stratum along with time is larger than the preset change rate, marking the moment as a first moment, and reducing the sand carrying ratio of the mixture to be a second sand carrying ratio;
the acquisition module is used for acquiring the volume of the precoated sand injected into the casing from the first moment in real time;
the injection module is also used for reducing the sand carrying ratio of the mixture to zero when the volume is equal to the preset volume;
and the timing module is used for closing the well and waiting for coagulation for a preset time period after the mixture replaces the residual precoated sand in the casing pipe with the oil outlet pipe, so that the precoated sand forms an artificial well bottom in the target stratum, and the precoated sand forms a sand plug with a preset height in the casing pipe.
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