A method for treating balling in active shale formations with oil-based drilling fluids

Abstract

The application discloses a treatment method for generating mud balls in oil-based drilling fluid in active sandstone and mudstone strata, and comprises the following steps: when mud balls appear in the oil-based drilling fluid and seriously affect normal drilling, a heavy thick slurry is prepared to clean the well and to reduce the concentration of drill cuttings in the annulus; a well slurry is prepared, a high-efficiency wetting agent is added, and the well slurry is pumped to the bottom of the well to be circulated uniformly, so that the surface properties of the drill cuttings are changed, and the drill cuttings are prevented from being coalesced into balls; a small amount of high-efficiency wetting agent is added to the well slurry to maintain the wetting effect, and the drill cuttings are prevented from being coalesced into mud balls again due to the consumption of drilling. The method has simple operation process, small amount of wetting agent, long time of maintaining the wetting performance of the oil-based drilling fluid, and can effectively reduce the operation risks such as pump blocking and drill sticking in the active sandstone and mudstone strata.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas field exploration and development, and particularly relates to a treatment method for mud ball generated in active sandstone and mudstone formation oil-based drilling fluid. BACKGROUND

[0002] With the increasing strength of oil and gas field exploration and development, the probability of drilling active sandstone and mudstone formation is also increasing. Active sandstone and mudstone formation is prone to mud making. In order to improve the drilling efficiency, the drilling fluid is prone to mud ball formation due to high concentration of drill cuttings in rapid drilling, especially in special structure wells such as high angle wells and large displacement wells. The phenomenon of mud ball formation is more obvious. The mud ball generated in the drilling process is easy to cause problems such as torque, pump pressure and tripping resistance caused by the narrowing of the annular space, which not only delays the operation time, but also brings hidden dangers to safe drilling.

[0003] At present, the industry generally uses oil-based drilling fluid with good inhibition or improves the inhibition and coating performance of the drilling fluid, reduces the mechanical drilling speed, reduces the rotation speed, and increases the displacement to inhibit the generation of mud ball. However, in active sandstone and mudstone formation, mud ball is generated even if oil-based drilling fluid with strong inhibition is used, and the engineering method will seriously affect the drilling operation efficiency. SUMMARY

[0004] In order to solve the above technical problems, the present application provides a treatment method for mud ball generated in active sandstone and mudstone formation oil-based drilling fluid, which can fully utilize the action mechanism of wetting agent to improve the effect of wetting drill cuttings, further improve the action effect of the added treatment agent, and reduce the material consumption.

[0005] The present application is achieved by adopting the following technical scheme.

[0006] A treatment method for mud ball generated in active sandstone and mudstone formation oil-based drilling fluid, comprising the following steps:

[0007] S1. When mud ball appears in the oil-based drilling fluid and seriously affects normal drilling, a high viscosity heavy mud is prepared to clean the well and reduce the concentration of drill cuttings in the annulus;

[0008] S2. A well slurry is prepared, a high-efficiency wetting agent is added, and the well slurry is pumped to the bottom of the well to circulate uniformly, change the surface properties of the drill cuttings, and prevent the drill cuttings from agglomerating into balls;

[0009] S3. A small amount of high-efficiency wetting agent is added to the whole well slurry to maintain its wetting effect and prevent the drill cuttings from forming mud balls again due to drilling consumption.

[0010] Further, in step S1, the high viscosity heavy mud is added to the organic soil or prepared according to the site demand on the basis of the well slurry.

[0011] Further, the funnel viscosity of the high-viscosity heavy slurry is 2 times the viscosity of the well slurry ± 20% s; the density of the high-viscosity heavy slurry is the density of the well slurry + (0.05-0.15) g / cm 3 , and the density is less than the equivalent circulating density of the formation fracture pressure.

[0012] Further, in step S1, the amount of the high-viscosity heavy slurry is determined based on the fact that the content of the drill cuttings returned after the well washing is less than 8%.

[0013] Further, in step S2, the well slurry is the oil-based drilling fluid being used when the mud ball appears.

[0014] Further, in step S3, the whole well slurry refers to the oil-based drilling fluid used during drilling.

[0015] Further, in step S2, the amount of the well slurry is 20-50 m 3 .

[0016] Further, in step S3, the amount of the whole well slurry is 400-800 m 3 .

[0017] Further, in steps S2 and S3, the high-efficiency wetting agent is selected from one or more of fatty acid wetting agents, organic amine wetting agents, polyoxyethylene ether wetting agents, cationic wetting agents, polyoxyethylene sulfonate wetting agents, petroleum sulfonate wetting agents, lecithin wetting agents, and polyhydric alcohol wetting agents.

[0018] Further, in step S2, the amount of the high-efficiency wetting agent in the well slurry is 50-100 kg / m 3 .

[0019] Further, in step S3, the amount of the high-efficiency wetting agent in the whole well slurry is 10-20 kg / m 3 .

[0020] The present application has the following beneficial effects.

[0021] (1) The present application reduces the annular cuttings concentration by using heavy slurry to wash the well, effectively reducing the addition amount of the high-efficiency wetting agent;

[0022] (2) The present application reduces the coalescence of the oil-based drilling fluid cuttings by using the wetting modification mechanism of the high-efficiency wetting agent on the surface of the cuttings, achieving the purpose of treating the mud ball and preventing the reformation of the mud ball;

[0023] (3) The present application can maintain the wetting performance of the oil-based drilling fluid for a long time, ensuring that the mud ball is not reformed, improving the drilling operation efficiency, and reducing the operation risk of active sandstone and mudstone formation pump blocking and sticking. DETAILED DESCRIPTION

[0024] The application will be further described in connection with the following examples.

[0025] Example 1

[0026] The well has a depth of 3688 m, a vertical depth of 2439 m, a maximum well deviation of 70.55°, and a bare hole section length of 1827 m. The drilling fluid used in the well is an oil-based drilling fluid. The drilling fluid is circulated to a depth of 3273 m, and then the drilling tool is replaced. During the circulation, a large amount of drill cuttings and a large amount of small mud balls are returned, and two large mud balls are returned, but the shaker screen is not blocked. The lithology of the layer is mainly gray sandstone, brownish gray mudstone, and grayish brown shale. The funnel viscosity of the drilling fluid is 72 s, and the density is 1.38 g / cm 3 .

[0027] The specific steps for solving the mud balls on site are as follows:

[0028] (1) A mud tank is prepared, and the effective volume is 30 m 3 . 220 kg of on-site organic soil is added to the mud tank through a shear pump to increase the funnel viscosity of the mud tank to 152 s. 5.6 t of on-site barite is added to the mud tank through a weighting pump to increase the density of the mud tank to 1.50 g / cm 3 . After sufficient shearing and stirring, the mud tank is pumped to the bottom of the well, the well is washed with heavy mud, and the high-concentration drill cuttings in the annulus are returned. The drill cuttings content of the returned drilling fluid is measured every 15 min until it is less than 8%, and then the washing is stopped.

[0029] (2) Another mud tank is introduced, and the effective volume is 30 m 3 . 3000 kg of a fatty acid derivative wetting agent (Jingzhou Jiahua Technology Co., Ltd., oil-based drilling fluid wetting agent JHWET) is added to the mud tank through a shear pump, and the wetting agent dosage is 100 kg / m 3 . After sufficient shearing and stirring, the mud tank is pumped to the bottom of the well, and then the pump is stopped.

[0030] (3) The pump is started to circulate, and the top drive is started to reverse the hole and move the drilling tool for 30 min. During the circulation process, the drilling parameters such as drilling pressure, displacement, and torque fluctuate very little, and no mud balls are returned.

[0031] (4) The drilling process is started, and the drilling parameters fluctuate little during the operation, and no mud balls are returned.

[0032] (5) After drilling for another 100 m, 3000 kg of a modified fatty acid derivative wetting agent (Jingzhou Jiahua Technology Co., Ltd., oil-based drilling fluid wetting agent JHWET) is added to the mud tank through a shear pump, and the total wetting agent dosage is 15 kg / m 3 (the total well mud is 400 m 3 ). The wetting effect of the drilling fluid is maintained to prevent the oil-based drilling fluid from generating mud balls again due to the consumption of the wetting agent.

[0033] (6) to the well drilling, drilling parameters during the operation process, no mud ball again.

[0034] Example 2

[0035] An oil well drilling depth of 2986m, vertical depth of 2534m, the maximum inclination of 35.41°, the length of the open hole section of 1264m. The drilling fluid used in the well is oil-based drilling fluid, the normal drilling to 2453m drilling parameters appear to return to fluctuation, and return to mud ball, from small to large, to the pipe shoe to large displacement circulation, return to a large number of mud ball, block the screen port. The lithology of this layer is mainly gray mudstone, light gray sandstone, the funnel viscosity of the drilling fluid is 68s, the density is 1.40g / cm 3 .

[0036] The specific steps of solving the mud ball generated on site are as follows:

[0037] (1) a mud tank is prepared, the effective volume is 25m 3 , 180kg of field organic soil is added to the tank through the shear pump to increase the funnel viscosity of the tank to 136s, 3.9t of field barite is added to the tank through the weighting pump to increase the density of the tank to 1.50g / cm 3 , and after full shear and uniform mixing, it is pumped to the bottom of the well, and the well is washed through the heavy slurry, and the high concentration of drill cuttings in the annulus is returned, the drill cuttings content of the returned drilling fluid is measured every 15min, and the washing is ended until it is less than 8%;

[0038] (2) another mud tank is introduced, the effective volume is 30m 3 , 800kg of fatty acid derivative wetting agent (Jingzhou Jiahua Technology Co., Ltd., oil-based drilling fluid wetting agent JHWET), 800kg of organic amine wetting agent (Jingzhou Jiahua Technology Co., Ltd., oleic acid diethyl triamine carboxylic acid wetting agent HIWET) and 800kg of polyoxyethylene ether wetting agent (Jingzhou Jiahua Technology Co., Ltd., isomerous decanol polyoxyethylene ether wetting agent MOWET) are added to the tank through the shear pump, and the wetting agent dosage is 80kg / m 3 . After full shear and uniform mixing, the pump is stopped after pumping to the bottom of the well;

[0039] (3) open pump circulation, and open top drive to reverse the hole and move the drilling tool for 30min, the drilling parameters such as pressure, displacement and torque fluctuate very little during the circulation process, and no mud ball is returned;

[0040] (4) start to resume drilling, the drilling parameters fluctuate little during the operation process, and no mud ball is returned;

[0041] (5) After drilling for another 100m, add 1000kg of fatty acid derivative wetting agent (Jingzhou Jia Hua Technology Co., Ltd., JHWET for oil-based drilling fluid), 1000kg of organic amine wetting agent (Jingzhou Jia Hua Technology Co., Ltd., HIWET for oleic acid diethylenetriamine carboxylic acid), and 1000kg of polyoxyethylene ether wetting agent (Jingzhou Jia Hua Technology Co., Ltd., MOWET for isomeric decaol polyoxyethylene ether) to the slurry circulation tank via a shear pump. The wetting agent dosage is 13.5kg / m. 3 (Total 400m of slurry in the well) 3 Maintain the wetting effect of the drilling fluid and prevent the formation of mud balls again in oil-based drilling fluids due to the consumption of wetting agents;

[0042] (6) Until the well was completed, the drilling parameters remained stable during the operation and no mud balls appeared again.

[0043] Example 3

[0044] An oil well was drilled to a total depth of 3180m, with a vertical depth of 2326m, a maximum inclination of 52.53°, and an open hole length of 1397m. The drilling fluid used was oil-based. During normal drilling, at 2775m, the well was pulled out to replace the NMR tool. Fluctuations in the circulating drilling parameters were observed, and mud balls, increasing in size, were gradually returned, clogging the vibrating screen. The lithology of this formation is mainly gray mudstone and gray siltstone. The drilling fluid funnel viscosity is 76s, and the density is 1.38 g / cm³. 3 .

[0045] The specific steps for resolving the mud balls generated on-site are as follows:

[0046] (1) A mud tank is used to prepare well mud, with an effective volume of 30m³. 3 By adding 240 kg of on-site organic soil using a shear pump, the viscosity of the well slurry funnel was increased to 152 s. Then, by adding 5.6 t of on-site barite using a weighting pump, the density of the well slurry was increased to 1.50 g / cm³. 3 After thorough shearing and mixing, the fluid is pumped to the bottom of the well and washed with a thick slurry. High concentrations of drill cuttings are returned from the annulus. The content of drill cuttings in the returned drilling fluid is measured every 15 minutes until it is less than 8%, at which point the well washing is stopped.

[0047] (2) Another mud tank is used to introduce well mud, with an effective volume of 40m³. 3, 800 kg of polyoxyethylene sulfonate wetting agent (Guangzhou Baining New Material Co., Ltd., carboxylate polyoxyethylene sodium sulfonate LMES), 800 kg of petroleum sulfonate wetting agent (Guangzhou Tongxin Chemical Co., Ltd., petroleum sulfonate sodium T702) and 800 kg of lecithin wetting agent (Hubei Sansen Chemical New Material Co., Ltd., soybean lecithin TEGO COLOROL F), 800 kg of polymeric alcohol wetting agent (Guangzhou Zhishun Chemical Co., Ltd., polyethylene glycol PEG4000) were added to the shearing pump, and the wetting agent dosage was 80 kg / m 3 . After sufficient shearing and uniform pumping to the bottom of the well, the pump was stopped;

[0048] (3) Open the pump circulation, and open the top drive to reverse the eye activity tool for 30 min. During the circulation process, the drilling parameters such as drilling pressure, displacement and torque fluctuate very little, and no mud ball is returned;

[0049] (4) Start to restore drilling, and the drilling parameters fluctuate little during the operation, and no mud ball is returned;

[0050] (5) After continuing to drill for 100 m, 1000 kg of polyoxyethylene sulfonate wetting agent (Guangzhou Baining New Material Co., Ltd., carboxylate polyoxyethylene sodium sulfonate LMES), 1000 kg of petroleum sulfonate wetting agent (Guangzhou Tongxin Chemical Co., Ltd., petroleum sulfonate sodium T702) and 1000 kg of lecithin wetting agent (Hubei Sansen Chemical New Material Co., Ltd., soybean lecithin TEGO COLOROL F), 1000 kg of polymeric alcohol wetting agent (Guangzhou Zhishun Chemical Co., Ltd., polyethylene glycol PEG4000) were added to the shearing pump, and the wetting agent dosage was 18 kg / m 3 (total mud 400 m 3 ). Keep the wetting effect of the drilling fluid to prevent the oil-based drilling fluid from generating mud balls again due to the consumption of wetting agent;

[0051] (6) The well is completed, and the drilling parameters are stable during the operation, and no mud ball is generated again.

[0052] Example 4

[0053] An oil well has a depth of 3676 m, a vertical depth of 2737 m, a maximum well inclination of 46.62°, and a bare hole section length of 1842 m. The drilling fluid used in the well is an oil-based drilling fluid. Normal drilling to 2162 m directional instrument has no signal, and the instrument is replaced during tripping. The drilling parameters fluctuate during the reverse eye circulation in the casing, and mud balls are returned in succession, from small to large, blocking the screen port. The lithology of this layer is mainly gray sandstone, brownish gray mudstone and grayish brown shale. The funnel viscosity of the drilling fluid is 62 s, and the density is 1.40 g / cm 3 .

[0054] The specific steps to solve the mud ball generated on site are as follows:

[0055] (1) A mud tank was prepared with a mud volume of 30 m 3 . 200 kg of on-site organic soil was added to the tank through a shear pump to increase the funnel viscosity of the tank to 136 s, and 4.7 t of on-site barite was added to the tank through a weighting pump to increase the density of the tank to 1.50 g / cm 3 . After sufficient shearing and mixing, the tank was pumped to the bottom of the well, the well was washed with heavy mud, and high-concentration drill cuttings were returned to the annulus. The drill cuttings content of the returned drilling fluid was measured every 15 min until it was less than 8% to end the well washing.

[0056] (2) The circulating backreaming active drill string was circulated for 30 min. During the circulation process, the parameters such as drilling pressure, displacement, and torque fluctuated very little, and no mud ball was returned.

[0057] (3) Drilling was resumed. During the initial drilling operation, the drilling parameters fluctuated little, and no mud ball was returned.

[0058] Drilling continued to 2522 m. The circulating drilling parameters fluctuated, and mud balls were returned one after another, from small to large, blocking the shale shaker port. The lithology of this layer was gray siltstone, variegated mudstone, and light gray fine sandstone. The funnel viscosity of the drilling fluid was 75 s, and the density was 1.42 g / cm 3 .

[0059] The specific steps for solving the mud balls generated on site are as follows:

[0060] (1) A mud tank was prepared with a mud volume of 30 m 3 . 1800 kg of fatty acid derivative wetting agent (Jingzhou Jiahua Technology Co., Ltd., oil-based drilling fluid wetting agent JHWET) was added to the tank through a shear pump, and the wetting agent dosage was 60 kg / m 3 . After sufficient shearing and mixing, the tank was pumped to the bottom of the well and the pump was stopped.

[0061] (2) The pump was started to circulate, and the top drive was started to circulate the backreaming active drill string for 30 min. During the circulation process, the parameters such as drilling pressure, displacement, and torque fluctuated very little, and no mud ball was returned.

[0062] (3) Drilling was resumed. During the operation, the drilling parameters fluctuated little, and no mud ball was returned.

[0063] Drilling continued to 2654 m. The circulating drilling parameters fluctuated, and mud balls were returned one after another, from small to large, blocking the shale shaker port. The lithology of this layer was gray siltstone, variegated mudstone, and light gray fine sandstone. The funnel viscosity of the drilling fluid was 76 s, and the density was 1.42 g / cm 3 .

[0064] The specific steps for solving the mud balls generated on site are as follows:

[0065] (1) Prepare a mud tank for slurry, effective volume 20m 3 , add 180kg of on-site organic soil to the tank slurry funnel to increase the funnel viscosity to 166s, add 2.5t of on-site barite to the tank slurry to increase the density to 1.50g / cm 3 , and pump it to the bottom of the well after sufficient shearing and mixing, wash the well with heavy slurry, return the high-concentration drill cuttings in the annulus, measure the drill cuttings content of the returned drilling fluid every 15min, and end the washing when it is less than 8%;

[0066] (2) Another mud tank is introduced into the well slurry, effective volume 30m 3 , add 2400kg of fatty acid derivative wetting agent (Jingzhou Jiahua Technology Co., Ltd., oil-based drilling fluid wetting agent JHWET) to the tank slurry, and the wetting agent dosage is 80kg / m 3 . After sufficient shearing and mixing, stop the pump after pumping to the bottom of the well;

[0067] (3) Start the pump to circulate, and open the top drive to reverse the eye and move the drill string for 30min. During the circulation process, the drilling parameters such as drilling pressure, displacement, torque, etc. fluctuate very little, and no mud ball is returned;

[0068] (4) Start to resume drilling, and the drilling parameters fluctuate little during the operation, and no mud ball is returned;

[0069] (5) Continue to drill for 100m, add 2400kg of modified fatty acid derivative wetting agent (Jingzhou Jiahua Technology Co., Ltd., oil-based drilling fluid wetting agent JHWET) to the well slurry circulation tank through the shearing pump, and the total wetting agent dosage is 16.5kg / m 3 (total well slurry 400m 3 ). Maintain the wetting effect of the drilling fluid to prevent the oil-based drilling fluid from generating mud balls again due to the consumption of the wetting agent;

[0070] (6) The well is completed, and the drilling parameters are stable during the operation, and no mud ball appears again.

[0071] The embodiments of the specific implementation are the preferred embodiments of the present application, but do not limit the protection scope of the present application, so that: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A method of treating active shale formations in oil-based drilling fluids to produce balling, characterized by: The method comprises the following steps: S1. When the mud ball appears in the oil-based drilling fluid and seriously affects the normal drilling, the high viscosity heavy mud is prepared to clean the well and reduce the concentration of drilling cuttings in the annulus; the funnel viscosity of the high viscosity heavy mud is 2 times ± 20% s of the well slurry; the density of the high viscosity heavy mud is the density of the well slurry + (0.05-0.15) g / cm 3 , and the density is less than the equivalent circulating density of the formation fracture pressure; S2. Formulate the well slurry, add high-efficiency wetting agent, pump to the bottom of the well to circulate uniformly, change the surface properties of the drill cuttings, and prevent the drill cuttings from coalescing into balls; S3. Add a small amount of high-efficiency wetting agent to the whole well slurry to maintain its wetting effect and prevent the drill cuttings from forming mud balls again due to drilling consumption; The high-efficiency wetting agent is selected from one or more of the following: fatty acid wetting agent, organic amine wetting agent, polyoxyethylene ether wetting agent, cationic wetting agent, polyoxyethylene sulfonate wetting agent, petroleum sulfonate wetting agent, lecithin wetting agent, and polyhydric alcohol wetting agent.

2. The method of claim 1, wherein the method is characterized by: In step S1, the high-viscosity heavy slurry is prepared by adding organic soil to the well slurry or by re-preparing according to the on-site demand.

3. The method of claim 1, wherein the method is characterized by: In step S1, the amount of high-viscosity heavy slurry is determined according to the fact that the content of drill cuttings returned after the well washing is less than 8%.

4. The method of claim 1, wherein the method is characterized by: In step S2, the well slurry is the oil-based drilling fluid being used when the mud balls appear.

5. The method of claim 1, wherein the method is characterized by: In step S3, the whole well slurry refers to the oil-based drilling fluid used during the drilling process.

6. The method of claim 1, wherein the method is characterized by: In step S2, the amount of well slurry is 20-50 m 3 ; in step S3, the amount of well slurry is 400-800 m 3 .

7. The method of claim 1, wherein the method is characterized by: In step S2, the amount of the high-efficiency wetting agent in the prepared well slurry is 50-100 kg / m 3 .

8. The method of claim 1, wherein the method is characterized by: In step S3, the amount of the high-efficiency wetting agent in the total slurry is 10-20 kg / m 3 .