String-free pumping high-density sand plug sand filling layering method

Abstract

The invention relates to a string-free pumping high-density sand plug sand filling layering method. The method comprises the steps of sand bottom surface detection and filling, sand filling construction design, prepad fluid pump injection, sand-carrying fluid pump injection, displacement fluid pump injection, pump stopping, well closing and sand setting, small-displacement trial extrusion and sand top surface detection and filling. The packer can achieve effective packing of fractured intervals, is reliable in plugging effect, wide in application range and capable of being applied to various underground complex conditions such as casing deformation and the like; procedures are simple, and construction efficiency is effectively improved; the advantages of multiple processes such as casing volume fracturing and sand plug soft packing are integrated, and a feasible technical means is provided for separate layer fracturing transformation of oil and gas resources.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field and hot dry rock development, and more particularly to a method for sand filling and layering by pumping high-density sand plugs without a tubing column. Background Art

[0002] Sand filling is a technical measure used to temporarily isolate the bottom reservoir and protect the production layer and casing in oilfield development. It has the advantages of simple operation, low construction investment and quick results. It has been widely used in oil and gas well filling, string testing, fishtop repair, fracturing and other aspects. At present, the common sand filling process adopts tubing sand filling technology. However, in on-site construction, tubing sand filling has problems such as inaccurate sand filling surface, sand filling blocking the tubing, sand bridge formed after sand filling and blocking the tubing, sand floating and not sinking after sand filling, resulting in no sand surface when exploring the sand surface or causing tubing to be stuck, and sand filling failing to fill into the tubing due to overflow. These poor sand filling conditions not only increase operating costs, but also greatly increase the risk of engineering accidents. Sand filling cannot be successful in one go, affecting the construction of the next measures. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for sand filling and layering without pipe column pumping high-density sand plugs, which can directly carry out sand filling construction in the casing and the open hole section, realize effective plugging of the opened layer section, and reduce the risk of sand filling.

[0004] The technical solution adopted by the present invention to solve the technical problem is to construct a method for sand filling and layering by pumping high-density sand plugs without a pipe column, comprising the following steps:

[0005] S1. Use the logging cable to run the tool string to softly probe the bottom of the sand filling and determine the position of the bottom of the sand filling;

[0006] S2. Calculate the sand filling volume, sand carrying fluid volume, and displacement fluid volume based on the bottom hole position and the next perforation position;

[0007] S3, pre-liquid pump injection: 0.5 ~ 3m 3 / min step-by-step construction displacement, pumping 0.5 to 1 times the wellbore volume to establish a pumping channel;

[0008] S4, sand-carrying liquid pump injection: 2 to 3m 3 / min construction displacement, pumping high sand ratio sand-carrying fluid until the calculated amount of quartz sand is fully entered into the wellbore, accurately measuring the pumping amount of sand-carrying fluid;

[0009] S5, displacement fluid pump injection: 0.5 ~ 3m 3 / min step-down construction displacement, pumping the designed amount of displacement fluid to displace the sand-carrying fluid to the preset target position;

[0010] S6. Stop the pump and shut down the well, and wait for the high sand ratio sand plug to break and settle naturally;

[0011] S7. Use small displacement test to compact the sand plug and test the sand filling effect;

[0012] S8. Use the logging cable to run the tool string to softly probe the bottom of the sand filling and determine the position of the top of the sand filling. The sand surface should be controlled within 0.15m to 0.5m.

[0013] According to the above solution, the sand carried by the sand-carrying fluid is a quartz sand proppant with a particle size ranging from 40 to 70 meshes.

[0014] According to the above scheme, the calculation method of the designed sand amount in step S2 is:

[0015]

[0016] L=MD 实测砂底位置 ~MD 砂顶设计位置 ;

[0017] MD 砂顶设计位置 =L 下一层射孔段底部炮眼位置 +L 预留口袋深度 ;

[0018] The reserved pocket depth is 10 to 15 meters.

[0019] According to the above scheme, the calculation method of the sand carrying fluid and displacement fluid volume in step S2 is: V 携砂液量 +V 顶替液量 =(80%~85%)V 井筒容积 .

[0020] According to the above scheme, the pre-fluid and displacement fluid are clean water.

[0021] According to the above solution, the sand-carrying fluid is a linear glue with a viscosity range of 20 to 40 mPa·s.

[0022] According to the above scheme, the sand-carrying fluid includes the following components, calculated by mass percentage: 0.3% to 0.5% thickener, 0.01% to 0.03% breaker, 0.2% to 0.4% clay stabilizer, and the rest is water.

[0023] According to the above scheme, the thickener is modified polyacrylamide with an average molecular weight of 17 million to 25 million; the clay stabilizer is a composite of KCl and NH4Cl, and the breaker is a capsule breaker.

[0024] According to the above scheme, the sand settling time after the sand plug is broken in step S6 is calculated as follows:

[0025] T 破胶后沉砂时间 =L 井筒剩余深度 / u 砂子在清水中的自由沉降速度

[0026] L井筒剩余深度 =MD 砂顶设计位置 -V 顶替液量 / V 每千米井筒容积

[0027] T 关井时间 =2×T 破胶后沉砂时间 .

[0028] According to the above scheme, in step S7, 0.5m 3 / min displacement for trial extrusion. If the pressure can rise to 80% of the casing's internal pressure resistance value or reach the construction pressure limit after 2 to 3 pressure tests, it can be determined that the sand filling layering is successful.

[0029] The implementation of the present invention's high-density sand plug filling and layering method without a pipe column pumping method has the following beneficial effects:

[0030] 1. The present invention solves the problems caused by conventional oil pipe sand filling, such as overflow sand filling in the wellbore that cannot be filled into the oil pipe, sand floating after filling and not sinking, forming sand bridges, and blocking the pipe string.

[0031] 2. The present invention can be applied to a variety of complex downhole situations, and can achieve effective isolation of the compressed layer section, thereby realizing staged fracturing of the reservoir and achieving the goal of large-scale fracturing.

[0032] 3. It can solve the problem of limited insertion of fracturing tools in casing changes and small wellbores, and this technology has outstanding advantages in safety, environmental protection, post-operation wellbore disposal and wellbore integrity.

[0033] 4. The invention is convenient to construct and takes a short time, shortening the oil testing period by 70%, thereby improving labor efficiency and reducing labor intensity. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0035] Figure 1 The present invention is a flow chart of a method for sand filling and layering of high-density sand plugs pumped without a tubing column. DETAILED DESCRIPTION

[0036] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0037] like Figure 1 As shown, the method for sand filling and layering of high-density sand plugs pumped without a tubing column of the present invention comprises the following steps:

[0038] S1: Exploring the bottom of the sand filling: When the lower sand surface is unclear, use the logging cable to run the tool string to softly explore the bottom of the sand filling to determine the position of the sand filling bottom surface;

[0039] S2: Sand filling design: Calculate the sand filling volume, sand carrying fluid volume, and displacement fluid volume based on the bottom hole position and the next perforation position;

[0040] S3: Pre-liquid pump injection: 0.5~3m 3 / min step-by-step construction displacement, pumping 0.5 to 1 times the wellbore volume to establish a pumping channel;

[0041] S4: Sand-carrying liquid pump injection: 2 to 3m 3 / min construction displacement, pumping high sand ratio sand-carrying fluid until the calculated amount of quartz sand is fully entered into the wellbore, accurately measuring the pumping amount of sand-carrying fluid;

[0042] S5: Displacement fluid pump injection: 0.5~3m 3 / min step-down construction displacement, pumping the designed amount of displacement fluid to displace the sand-carrying fluid to the preset target position;

[0043] S6: Stop pump and shut down well to settle sand: Stop pump and shut down well, and wait for the high sand ratio sand plug to break and settle naturally;

[0044] S7: small displacement test: using 0.5m 3 / min test squeeze, compact the sand plug and test the sand filling effect at the same time, test the pressure 2 to 3 times, the test pressure value reaches 80% of the casing's internal pressure resistance or the pressure limit value of the construction design, and stabilize the pressure for 5 minutes, which is qualified.

[0045] S8: Exploring the top surface of the sand filling: Use the logging cable to run the tool string to softly explore the bottom surface of the sand filling to determine the position of the top surface of the sand filling. The sand surface should be controlled within 0.15m to 0.5m.

[0046] The applicable well conditions of the process method of the present invention are vertical wells or directional wells in which the production layer at the lower part has been transformed and the upper part is perforated for production.

[0047] Preferably, the pre-fluid and displacement fluid can be clean water or active water.

[0048] Preferably, the sand-carrying fluid is a linear gel with a viscosity range of 20 to 40 MPa·s, and its mass percentage composition is 0.3% to 0.5% modified polyacrylamide, 0.01% to 0.03% gel breaker, and 0.2% to 0.4% clay stabilizer. The modified polyacrylamide has an average molecular weight of 17 to 25 million; the clay stabilizer is a composite of KCl and NH4Cl.

[0049] Preferably, the sand selected is quartz sand with 40-70 mesh for fracturing, which has round particles, uniform particle size, good sorting, few impurities, high resistance to breakage and easy to carry. For wells with overflow, ceramsite sand for fracturing is selected.

[0050] Preferably, the sand bottom exploration tool string combination in S1 is: Φ11.8mm cable + bridle + magnetic positioning + weight 1 + weight 2.

[0051] Preferably, in step S2, the sand filling amount, the free settling velocity of the sand, and the sand-carrying liquid breaking time are calculated as follows:

[0052] (1) Calculation of sand filling volume

[0053]

[0054] L=MD 实测砂底位置 -MD 砂顶设计位置

[0055] MD 砂顶设计位置 =L 下一层射孔段底部炮眼位置 +L 预留口袋深度 , the reserved pocket depth is 10 to 15m;

[0056] Where V 填砂量 is the sand filling volume, m 3 ; K is the additional coefficient, ranging from 1.05 to 1.30; D is the inner diameter of the casing, mm; L is the sand filling thickness, m; MD 砂顶设计位置 Design the well depth of the top interface of the sand filling (reserving a pocket of 10 to 15 meters or more), m; MD 实测砂底位置 is the well depth of the soft exploration sand fill bottom, m.

[0057] (2) During the pumping and displacement phase, when the pumping volume is less than 0.5m 3 / min, the sand settling velocity is calculated as:

[0058] U 砂子沉降速度 =u 泵注速度 +u 自由沉淀速度

[0059] Where u 泵注速度 =Q 泵注排量 / V 1m井筒容积 , Q 泵注排量 (m 3 / S), V 1m井筒容积 The volume of the wellbore is 1m (m 3 / m).

[0060] (3) The free sedimentation rate of sand in the wellbore, obtained through sedimentation tests or theoretical calculations:

[0061] u 砂子自由沉降速度 =gd 2 (ρs-ρ) / 18μ

[0062] u 砂子自由沉降速度 , cm / s;

[0063] ρs and ρ are the densities of the particle and the sand-carrying fluid, respectively, in g / cm; g is the acceleration due to gravity, in cm / s; μ is the adhesion coefficient of the sand-carrying fluid, in Pa·s; and d is the particle diameter, in cm.

[0064] (4) Sand-carrying fluid breaking time: obtained through experiments under indoor simulated wellbore temperature conditions.

[0065] Preferably, in step S3, the method for calculating the amount of the pre-fluid pump is:

[0066] V 前置液泵注量 =V 井筒容积 ×(0.5~1);

[0067] V 井筒容积 : Wellbore volume from wellhead to perforation position, m 3 .

[0068] Preferably, in step S4, the method for calculating the amount of sand-carrying liquid is:

[0069] V 携砂液量 =V 填砂量 / R 砂比

[0070] Where R 砂比 Take 30% to 35%, V 携砂液量 is the volume of sand-carrying fluid, m 3 ;

[0071] Preferably, in step S5, in order to prevent quartz sand from entering the formation and affecting the sand filling accuracy, the displacement fluid volume is calculated as follows:

[0072] V 顶替液量 =(80%~85%)×V 井筒容积 -V 携砂液量 ;

[0073] Where V 顶替液量 : displacement fluid volume m 3 ; V 井筒容积 : Wellbore volume from wellhead to perforation position, m 3 .

[0074] Preferably, in step S6, the sand settling time after the sand plug is broken is calculated as follows:

[0075] T 破胶后沉砂时间 =L 井筒剩余深度 / u 砂子在清水中的自由沉降速度

[0076] L 井筒剩余深度 =MD 砂顶设计位置 -V 顶替液量 / V 每千米井筒容积

[0077] T shut-in time = 2 × T破胶后沉砂时间 .

[0078] The present invention also provides a specific engineering example as follows:

[0079] A method for sand filling and layering of high-density sand plugs pumped without a tubing column comprises the following steps:

[0080] Step 1: Probe the bottom of the sand filling

[0081] (1) Wellbore structure: 177.8 mm casing × 4695.673 m + 149.2 mm open hole section × 4892.0 m + 148 mm open hole section × 4894.28 m.

[0082] (2) Using the logging cable, the tool string of "Φ11.8mm cable + bridle + magnetic positioning + weight 1 + weight 2" was lowered to softly explore the bottom of the sand fill and determine that the bottom of the sand fill was 4894.28m.

[0083] Step 2: Sand filling construction design

[0084] (1) Total wellbore volume: 89.29m 3 =Casing section wellbore volume: 85.82m 3 +Open hole section wellbore volume: 3.47m 3 .

[0085] (2) Casing data: 177.8×12.65mmTP140V, internal pressure resistance 120.2MPa.

[0086] (2) According to MD 砂底位置 and the next perforation position 4730m, clear MD 砂底位置 4894.28m, MD 砂顶位置 =4745m (the bottom blasthole position of the next perforated section is 4730m + the reserved pocket depth is 15m), calculate the sand filling thickness: L = MD 砂底位置 ~MD 砂顶位置 =149.28m.

[0087] (3) According to the sand filling volume calculation formula: V sand = (πD^2) / 4LK, D is 0.02m, K is 1.05, and L is 149.28m, the sand filling volume of 40-70 mesh quartz sand is calculated to be 2.73m 3 .

[0088] (4) Sand-carrying fluid breaking time: According to indoor experiments, at ≥90°C, with a 0.03% breaker dosage, the breaking time is complete in 20 minutes, and the viscosity of the breaking fluid is 1.8 mPa·s.

[0089] Step 3: Fill the pre-fluid pump

[0090] Use 0.5~3m 3 / min step-up construction displacement, pumping 44.6m 3 Clean water (0.5 times the wellbore volume) is used to establish a pumping channel.

[0091] Step 4: Pumping sand-carrying fluid

[0092] 2~3m 3 / min construction displacement, pumping 7.8m3 of sand-carrying fluid with a sand ratio of 35% 3 Until all the calculated amount of quartz sand enters the wellbore;

[0093] Step 5: Pump the displacement fluid:

[0094] 0.5~3m 3 / min step-down construction displacement, pumping displacement 63.6m 3 Clean water will replace the sand-carrying fluid to the preset target position.

[0095] Step 6: Stop the pump, shut down the well and let the sand settle

[0096] (1) Calculate according to the formula:

[0097] The location of the sand plug after the pump is stopped: 3484.73m~3901.64m

[0098] The sedimentation rate of quartz sand in clean water is 0.0855m / s

[0099] Sedimentation time: (4745~3484.73) / 0.0855=4.09h

[0100] (2) The well should be shut in for no less than 8.18 hours, until the high sand ratio sand plug breaks and settles naturally to the bottom of the well.

[0101] Step 7: Test squeeze with a small volume

[0102] Use 0.5m 3 / min test extrusion, 2 to 3 times of pressure test, the test pressure value reaches 80% of the casing's internal pressure resistance or the pressure limit value of the construction design, and the pressure is stabilized for 5 minutes, which is qualified.

[0103] Step 8: Probe the top surface of the sand filling:

[0104] Use a logging cable to run a tool string through the sandfill to softly probe the bottom and determine the top of the sandfill. The sandfill surface should be controlled within 0.15m to 0.5m. If the measured sandfill surface is more than 2m higher than the design value, use coiled tubing to flush the sand to the design value.

[0105] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A method for sand filling and layering of high-density sand plugs without pipe column pumping, characterized in that: The steps include: S1. Use the logging cable to run the tool string to softly probe the bottom of the sand filling and determine the position of the bottom of the sand filling; S2. Calculate the sand filling volume, sand carrying fluid volume, and displacement fluid volume based on the bottom hole position and the next perforation position; S3, pre-liquid pump injection: 0.5 ~ 3m 3 / min step-by-step construction displacement, pumping 0.5 to 1 times the wellbore volume to establish a pumping channel; S4, sand-carrying liquid pump injection: 2 to 3m 3 / min construction displacement, pumping high sand ratio sand-carrying fluid until the calculated amount of quartz sand is fully entered into the wellbore, accurately measuring the pumping amount of sand-carrying fluid; S5, displacement fluid pump injection: 0.5 ~ 3m 3 / min step-down construction displacement, pumping the designed amount of displacement fluid to displace the sand-carrying fluid to the preset target position; S6. Stop the pump and shut down the well, and wait for the high sand ratio sand plug to break and settle naturally; S7. Use small displacement test to compact the sand plug and test the sand filling effect; S8. Use the logging cable to run the tool string to softly probe the bottom of the sand filling and determine the position of the top of the sand filling. The sand surface should be controlled within 0.15m to 0.5m.

2. The method for sand filling and layering of high-density sand plugs pumped without a pipe column according to claim 1, characterized in that: The sand carried by the sand-carrying fluid is a quartz sand proppant with a particle size ranging from 40 to 70 meshes.

3. The method for sand filling and layering of high-density sand plugs pumped without a pipe column according to claim 1, characterized in that: The calculation method of the designed sand amount in step S2 is: L=MD 实测砂底位置 ~MD 砂顶设计位置 ; MD 砂顶设计位置 =L 下一层射孔段底部炮眼位置 +L 预留口袋深度 ; The reserved pocket depth is 10 to 15 meters.

4. The method for sand filling and layering of high-density sand plugs pumped without a pipe column according to claim 1, characterized in that: The calculation method for the amount of sand-carrying fluid and displacement fluid designed in step S2 is: V 携砂液量 +V 顶替液量 =(80%~85%)V 井筒容积 .

5. The method for sand filling and layering of high-density sand plugs pumped without a pipe column according to claim 1, characterized in that: The pre-fluid and displacement fluid are clean water.

6. The method for sand filling and layering of high-density sand plugs pumped without a pipe column according to claim 1, characterized in that: The sand-carrying fluid is a linear glue with a viscosity range of 20 to 40 mPa·s.

7. The method for sand filling and layering of high-density sand plugs pumped without a pipe column according to claim 1, characterized in that: The sand-carrying fluid comprises the following components, calculated by mass percentage: 0.3% to 0.5% of a thickener, 0.01% to 0.03% of a gel breaker, 0.2% to 0.4% of a clay stabilizer, and the remainder being water.

8. The method for sand filling and layering of high-density sand plugs pumped without a pipe column according to claim 7, characterized in that: The thickener is modified polyacrylamide with an average molecular weight of 17 million to 25 million; the clay stabilizer is a composite of KCl and NH4Cl; and the breaker is a capsule breaker.

9. The method for sand filling and layering of high-density sand plugs pumped without a pipe column according to claim 1, characterized in that: The calculation method of the sand settling time after the sand plug is broken in step S6 is as follows: T 破胶后沉砂时间 =L 井筒剩余深度 / u 砂子在清水中的自由沉降速度 L 井筒剩余深度 =MD 砂顶设计位置 -In 顶替液量 / V 每千米井筒容积 T 关井时间 =2×T 破胶后沉砂时间 。 10. The method for sand filling and layering of high-density sand plugs pumped without a pipe column according to claim 1, characterized in that: In step S7, 0.5 m 3 / min displacement for trial extrusion. If the pressure can rise to 80% of the casing's internal pressure resistance value or reach the construction pressure limit after 2 to 3 pressure tests, it can be determined that the sand filling layering is successful.

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