Tail pipe fixing process for heavy oil thermal production well in workover treatment

Abstract

The invention relates to the technical field of oil field workover treatment, in particular to a heavy oil thermal production well tail pipe fixing process for workover treatment. The process comprises the following steps that according to physical property characteristics, combination, distribution and section lengths of different stratums, corresponding composite cement paste is selected and prepared for well cementation, and the composite cement paste comprises plugging cement paste, thixotropic cement paste, high-density cement paste and conventional cement paste. According to the method, well cementation cement paste with different properties is selected in a targeted mode for well cementation according to different well conditions and overall distribution and section lengths of different stratums, and the well cementation quality is good.

Description

Technical field:

[0001] The invention relates to the technical field of oilfield well repair operations, and in particular to a tail pipe fixing process for heavy oil thermal recovery wells used in well repair operations. Background technology:

[0002] Existing heavy oil thermal recovery wells have the following characteristics:

[0003] 1. The permeability of the oil layer is large, the formation skeleton is loosely cemented, there is a lot of sand, and the mining process causes holes to form in the oil layer.

[0004] 2. Deficiency and leakage of mining layer.

[0005] 3. The oil layer is shallowly buried, the fracture pressure is low, and channeling is easily formed between the two wells.

[0006] 4. There is channel leakage and pipe leakage between the high-pressure (water injection) water layer and the mining layer.

[0007] 5. The oil layer is prone to sand production and accumulation in the wellbore.

[0008] 6. Conditions required for cementing: The fluid pressure coefficient in the wellbore is greater than the formation pressure coefficient. The formation is stable, and there is no large amount of sand, overflow, or leakage during cementing.

[0009] 7. Cementing requirements for cement slurry performance: can plug leaks, can suppress large amounts of sand and water production, and cannot leak formations.

[0010] At present, there are the following problems when fixing the tail pipe:

[0011] 1. Oil layer loss.

[0012] 2. High-pressure water leakage in the water layer.

[0013] 3. The pressure coefficient of the water layer in the wellbore is large, while the pressure coefficient of the oil layer is small.

[0014] 4. During cementing, it is difficult for the wellbore liquid to balance the formation pressure; too low pressure in the leakage layer is not conducive to cementing.

[0015] Therefore, the following technical problems need to be solved:

[0016] Unfavorable factors for cementing caused by high permeability leakage zone in open hole section: leakage cannot be recovered during cementing.

[0017] Unfavorable factors of cementing caused by sandy layers: sand accumulation and blockage during pump stop, resulting in leakage of the formation.

[0018] Unfavorable factors for cementing caused by water penetration during high-pressure water injection: water flows out, disperses and dilutes the cement slurry and carries out some formation sand.

[0019] Steam channeling causes bubbles to form in the mud, reduces mud density, and increases mud temperature.

[0020] Eliminate the factors that affect the cementing quality in heavy oil thermal recovery wells due to the presence of various formations with different pressure coefficients. Comprehensively consider the factors that affect the cementing quality caused by the characteristics of several formations, and select cement slurries with different properties to solve the cementing problem. Summary of the invention:

[0021] The technical problem to be solved by the present invention is to provide a tail pipe cementing process for heavy oil thermal recovery wells for well repair operations. The process realizes targeted selection of cementing slurries with different properties for cementing according to different well conditions, overall distribution and section lengths of different formations, and has good cementing quality.

[0022] The technical solution adopted by the present invention is: a tail pipe cementing process for heavy oil thermal recovery wells for well repair operations, the process comprising: selecting corresponding composite cement slurry for cementing according to the physical properties, combination, distribution and section length of different formations, wherein the composite cement slurry includes plugging cement slurry, thixotropic cement slurry, high-density cement slurry and conventional cement slurry;

[0023] 1. Composite cement slurry performance requirements:

[0024] a. After the plugging cement slurry is plugged, the pressure of the leakage layer meets the wellbore pressure balance requirement during cementing. If the leakage layer is an exploitation layer, the plugging cement slurry meets the exploitation requirements, that is, the plugging cement slurry has a certain permeability after solidification; the plugging cement slurry performance: water loss 500-900mL / 30min, consistency 35-40BC, equivalent density ρ 漏 1.70-1.80g / cm 3 ; The permeability of the plugging cement slurry after forming cement stone is 300-2600 (10 -3 μm 2 ), porosity 0.25-0.32;

[0025] b. The thixotropic cement slurry meets the requirements of preventing quicksand aggregation during cementing and also meets the requirements of wellbore pressure balance and cementing quality acceptance during cementing; the thixotropic cement slurry performance: initial consistency ≦30BC, transition time ≦5min, thickening mutation value 30-40BC, thickening time shortening value 60min, equivalent density ρ 触 1.85-1.90g / cm 3 ;

[0026] c. The high-density cement slurry is used to balance the high-pressure water layer pressure and can prevent the formation fluid from entering the wellbore. The equivalent density ρ 高 1.70-2.60g / cm 3 ;

[0027] 2. Calculation of the amount of composite cement slurry:

[0028] d. The dosage of the plugging cement slurry is calculated by the following formula through the model:

[0029] Formula 1: V 堵漏 =πr 堵漏 2 h 堵漏 φ(P 堵漏泵压 +P 井筒液柱压力 ) / γP 原地层

[0030] In the above formula: V 堵漏 is the amount of cement slurry for plugging leaks, in m 3 ;

[0031] π is the ratio of a circle to a circle;

[0032] r 堵漏 is the plugging radius, in m;

[0033] h 堵漏 is the formation thickness of the lost well section, in m;

[0034] φ is the effective porosity of the formation;

[0035] P 堵漏泵压 The plugging pump pressure is greater than or equal to the maximum cementing pump pressure, in Pa;

[0036] P 井筒液柱压力 is the wellbore liquid column pressure, in Pa;

[0037] γ is the viscosity coefficient of the liquid, and its value is the funnel viscosity of the plugging cement slurry divided by the funnel viscosity of clean water;

[0038] P 原地层 is the original formation pressure of the leakage section, in Pa;

[0039] e. Calculation of the amount of thixotropic cement slurry, high-density cement slurry and conventional cement slurry:

[0040] The equivalent density of the plugging cement slurry ρ 漏 , Thixotropic cement paste equivalent density ρ 触 , Thixotropic cement slurry height h 触 , high density cement paste equivalent density ρ 高 , high density cement slurry height h 高 、Conventional cement paste equivalent density ρ 常 , conventional cement slurry height h normal, wellbore balance pressure P 平衡 , Wellbore pressure balance equivalent density ρ 平衡 , cementing depth H 井深 , additional pressure P 附加 , water channeling pressure P 水窜 , the gravitational acceleration g needs to satisfy the following relationship;

[0041] Relationship 1: P 平衡 =ρ 漏 gh 漏 +ρ 高 gh 高 +ρ 触 gh 触 +ρ 常 gh 常 +P 附加

[0042] Relationship 2: H 井深 =h 漏 +h 高 +h 触 +h 常

[0043] Relationship 3: P 平衡 =ρ 平衡 HkDJ 井深 +P 附加

[0044] Relationship 4: P 漏 =ρ 漏 gh 漏

[0045] Relationship 5: P 高 =ρ 高 gh 高

[0046] Relationship 6: P 触 =ρ 触 gh 触

[0047] Relationship 7: P 常 =ρ 常 gh 常

[0048] When the water breakthrough pressure is the highest formation pressure, the following equations 8 and 9 are obtained:

[0049] Relationship 8: P 平衡 =P 水窜 +P 附加

[0050] Relationship 9: P 水窜 =ρ 水窜 gh 水窜

[0051] Relationship 10: P 漏 =ρ 漏 gh 漏 =0, the plugging cement slurry completely enters the formation, that is, the pressure generated by the plugging cement slurry in the wellbore is 0;

[0052] In the above relationship: P 平衡 is the wellbore equilibrium pressure, in Pa;

[0053] ρ 漏 is the equivalent density of plugging cement slurry, in g / cm 3 ;

[0054] h 漏 is the height of the plugging cement slurry. When the plugging cement slurry completely enters the formation, h 漏 is 0, unit is m;

[0055] g is the acceleration due to gravity, 9.81 m / s2;

[0056] ρ 高 is the equivalent density of high-density cement paste, in g / cm 3 ;

[0057] h 高 is the height of high-density cement slurry, in m;

[0058] ρ 触 is the equivalent density of thixotropic cement paste, in g / cm 3 ;

[0059] h 触 is the height of thixotropic cement slurry, in m;

[0060] ρ 常 is the equivalent density of conventional cement paste, in g / cm 3 ;

[0061] h 常 is the height of conventional cement slurry, in m;

[0062] P 附加 is the additional pressure, in Pa;

[0063] H 井深 is the depth of the well bottom, in m;

[0064] ρ 平衡 is the wellbore pressure balance equivalent density, in g / cm 3 ;

[0065] P 漏 is the plugging cement slurry column pressure, in Pa;

[0066] P 高 is the high-density cement slurry column pressure, in Pa;

[0067] P 触 is the thixotropic cement slurry column pressure, in Pa;

[0068] P常 is the conventional cement slurry column pressure, in Pa;

[0069] P 水窜 is the water channeling layer pressure, in Pa;

[0070] ρ 水窜 , is the water channeling layer pressure equivalent density, unit is g / cm 3 ;

[0071] h 水窜 , is the depth of the middle part of the water channeling layer, in m;

[0072] According to the above relationship, ρ is selected 漏 , 触 、h 触 , 高 、h 高 , 常 、h 常 The specific value of can be used to determine the volume usage of thixotropic cement slurry, high-density cement slurry and conventional cement slurry based on the test well diameter.

[0073] Furthermore, the plugging cement slurry has a permeability consistent with that of the original stratum after solidification.

[0074] Furthermore, the plugging cement slurry contains plant fibers and polypropylene high-temperature degradable particles.

[0075] Furthermore, in the plugging cement slurry, the volume ratio of cement slurry: plant fiber: polypropylene high temperature degradation particles is 1:0.2:0.2, wherein the diameter of the polypropylene high temperature degradation particles is 3-6 mm.

[0076] Furthermore, the formation pressure after plugging by the plugging cement slurry is not less than the system balance pressure during cementing, that is, P 地层承压 ≥P 平衡 +0.6.

[0077] The beneficial effects of the present invention are:

[0078] 1. According to different well conditions, the overall distribution and section length of different formations, cement slurries with different properties are selected for cementing in a targeted manner to ensure good cementing quality.

[0079] 2. After the plugging cement slurry enters the leakage layer, the leakage layer meets the pressure balance requirement of the cementing wellbore. If the leakage layer is a mining layer, the plugging cement slurry can also meet the mining needs. The cement slurry has a certain porosity permeability after solidification.

[0080] 3. Thixotropic cement slurry not only meets the requirements of preventing quicksand accumulation during cementing, but also meets the requirements of wellbore pressure balance and cementing quality acceptance during cementing.

[0081] 4. High-density cement slurry is used to balance the pressure of high-pressure water layers, prevent formation water from entering the wellbore, and prevent formation steam from entering the wellbore. Description of the drawings:

[0082] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0083] Figure 1 This is a diagram of electrical measurement results of acoustic amplitude / variable density detection of cementing quality in Example 1 of the present invention. Specific implementation method:

[0084] The construction process of the tail pipe for heavy oil thermal recovery well is as follows:

[0085] Based on the Engineering Design, Geological Design and data provided during open hole drilling, the equivalent density and dosage of plugging cement slurry, thixotropic cement slurry, high-density cement slurry and conventional cement slurry in the composite cement slurry are calculated to carry out cementing operations.

[0086] 1. Wellbore preparation: The drilling tools are used in the same combination as during drilling to clear the well. If any obstruction is encountered, the hole is expanded and reamed.

[0087] 2. Adjust the mud: viscosity, shear force, water loss, density, friction coefficient, sand content, n value, k value, solid content and inhibition should meet the requirements of cementing.

[0088] 3. Cement slurry preparation: Prepare cementing slurry according to the well history, formation conditions and mud conditions.

[0089] 4. Lower tail pipe: lower float hoop, float shoe, tail pipe, hollow rubber plug, hanger and other pipe strings.

[0090] 5. Circulating well washing: After the tail pipe is in place, circulate the workover fluid for more than one week.

[0091] 6. Invert the hanger: Hang the hanger and invert the center tube.

[0092] 7. Cement the well according to the design parameters, and inject spacer fluid + plugging cement slurry + thixotropic cement slurry + high-density cement slurry + conventional cement slurry in sequence. (When the plugging cement slurry enters the leakage layer, close the wellhead annulus sealer, and open the annulus anti-collision device after squeezing the plugging cement slurry into the formation)

[0093] 8. Insert the small rubber plug and pump in the displacement fluid.

[0094] 9. Impact and pressure: The small rubber plug and the hollow rubber plug are combined and then move downward to the spoiler for impact and pressure.

[0095] 10. Lift the pipe string: lift the center pipe upward and disengage the hanger, and continue to lift the pipe string to the designed depth.

[0096] 11. Circulating well washing: Circulating well washing washes out excess cement slurry in the well.

[0097] 12. Pull up the drill bit and wait for solidification: lift the drill bit 200-300m, shut in the well and wait for solidification.

[0098] 13. Plug sweeping: lower the drill bit to sweep away the cement plug in the wellbore.

[0099] 14. Well cleaning: Lower the diameter gauge to clean the well to the designed position and circulate and clean the well for more than one week.

[0100] 15. Test: Measure the acoustic amplitude / variable density to detect the quality of the solid tail pipe and complete the well.

[0101] Example 1

[0102] On January 8, 2023, the Shu 1-46-Geng 36 well adopted the process of the present invention and achieved complete success.

[0103] Measuring sound amplitude / variable density to detect cementing quality electrical measurement results such as Figure 1 As shown, the cementing quality pass rate is 100% and the full excellence rate is 93%.

[0104] It can be understood that the above specific description of the present invention is only used to illustrate the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that the present invention can still be modified or replaced by equivalents to achieve the same technical effects; as long as the use requirements are met, they are within the protection scope of the present invention.

Claims

1. A tail pipe fixing process for heavy oil thermal recovery wells used in well repair operations, characterized in that: The process includes the following: according to the physical characteristics, combination, distribution and section length of different formations, the corresponding composite cement slurry is selected for cementing, wherein the composite cement slurry includes plugging cement slurry, thixotropic cement slurry, high-density cement slurry and conventional cement slurry; 1. Composite cement slurry performance requirements: a. After the plugging cement slurry is plugged, the pressure of the leakage layer meets the wellbore pressure balance requirement during cementing. If the leakage layer is an exploitation layer, the plugging cement slurry meets the exploitation requirements, that is, the plugging cement slurry has a certain permeability after solidification; the plugging cement slurry performance: water loss 500-900mL / 30min, consistency 35-40BC, equivalent density ρ 漏 1.70-1.80g / cm 3 ; The permeability of the plugging cement slurry after forming cement stone is 300-2600 (10 -3 μm 2 ), porosity 0.25-0.32; b. The thixotropic cement slurry meets the requirements of preventing quicksand aggregation during cementing and also meets the requirements of wellbore pressure balance and cementing quality acceptance during cementing; the thixotropic cement slurry performance: initial consistency ≦30BC, transition time ≦5min, thickening mutation value 30-40BC, thickening time shortening value 60min, equivalent density ρ 触 1.85-1.90g / cm 3 ; c. The high-density cement slurry is used to balance the high-pressure water layer pressure and can prevent the formation fluid from entering the wellbore. The equivalent density ρ 高 1.70-2.60g / cm 3 ; 2. Calculation of the amount of composite cement slurry: d. The dosage of the plugging cement slurry is calculated by the following formula through the model: Formula 1: V 堵漏 =πr 堵漏 2 h 堵漏 φ(P 堵漏泵压 +P 井筒液柱压力 ) / γP 原地层 In the above formula: V 堵漏 is the amount of cement slurry for plugging leaks, in m 3 ; π is the ratio of a circle to a circle; r 堵漏 is the plugging radius, in m; h 堵漏 is the formation thickness of the lost well section, in m; φ is the effective porosity of the formation; P 堵漏泵压 The plugging pump pressure is greater than or equal to the maximum cementing pump pressure, in Pa; P 井筒液柱压力 is the wellbore liquid column pressure, in Pa; γ is the viscosity coefficient of the liquid, and its value is the funnel viscosity of the plugging cement slurry divided by the funnel viscosity of clean water; P 原地层 is the original formation pressure of the leakage section, in Pa; e. Calculation of the amount of thixotropic cement slurry, high-density cement slurry and conventional cement slurry: The equivalent density of the plugging cement slurry ρ 漏 , Thixotropic cement paste equivalent density ρ 触 , Thixotropic cement slurry height h 触 , high density cement paste equivalent density ρ 高 , high density cement slurry height h 高 、Conventional cement paste equivalent density ρ 常 , conventional cement slurry height h normal, wellbore balance pressure P 平衡 , Wellbore pressure balance equivalent density ρ 平衡 , cementing depth H 井深 , additional pressure P 附加 , water channeling pressure P 水窜 , the gravitational acceleration g needs to satisfy the following relationship; Relationship 1: P 平衡 =ρ 漏 gh 漏 +ρ 高 gh 高 +ρ 触 gh 触 +ρ 常 gh 常 +P 附加 Relationship 2: H 井深 =h 漏 +h 高 +h 触 +h 常 Relationship 3: P 平衡 =ρ 平衡 HkDJ 井深 +P 附加 Relationship 4: P 漏 =ρ 漏 gh 漏 Relationship 5: P 高 =ρ 高 gh 高 Relationship 6: P 触 =ρ 触 gh 触 Relationship 7: P 常 =ρ 常 gh 常 When the water breakthrough pressure is the highest formation pressure, the following equations 8 and 9 are obtained: Relationship 8: P 平衡 =P 水窜 +P 附加 Relationship 9: P 水窜 =ρ 水窜 gh 水窜 Relationship 10: P 漏 =ρ 漏 gh 漏 =0, the plugging cement slurry completely enters the formation, that is, the pressure generated by the plugging cement slurry in the wellbore is 0; In the above relationship: P 平衡 is the wellbore equilibrium pressure, in Pa; ρ 漏 is the equivalent density of plugging cement slurry, in g / cm 3 ; h 漏 is the height of the plugging cement slurry. When the plugging cement slurry completely enters the formation, h 漏 is 0, unit is m; g is the acceleration due to gravity, 9.81 m / s2; ρ 高 is the equivalent density of high-density cement paste, in g / cm 3 ; h 高 is the height of high-density cement slurry, in m; ρ 触 is the equivalent density of thixotropic cement paste, in g / cm 3 ; h 触 is the height of thixotropic cement slurry, in m; ρ 常 is the equivalent density of conventional cement paste, in g / cm 3 ; h 常 is the height of conventional cement slurry, in m; P 附加 is the additional pressure, the unit is Pa; H 井深 is the cementing depth, in m; ρ 平衡 is the wellbore pressure balance equivalent density, in g / cm 3 ; P 漏 is the plugging cement slurry column pressure, in Pa; P 高 is the high-density cement slurry column pressure, in Pa; P 触 is the thixotropic cement slurry column pressure, in Pa; P 常 is the conventional cement slurry column pressure, in Pa; P 水窜 is the water channeling layer pressure, in Pa; ρ 水窜 , is the water channeling layer pressure equivalent density, unit is g / cm 3 ; h 水窜 , is the depth of the middle part of the water channeling layer, in m; According to the above relationship, ρ is selected 漏 , 触 、h 触 , 高 、h 高 , 常 、h 常 The specific value of can be used to determine the volume usage of thixotropic cement slurry, high-density cement slurry and conventional cement slurry based on the test well diameter.

2. The tail pipe consolidation process for heavy oil thermal recovery wells used in well repair operations according to claim 1, characterized in that: The plugging cement slurry has the same permeability as the original stratum after solidification.

3. The tail pipe consolidation process for heavy oil thermal recovery wells used in well repair operations according to claim 1, characterized in that: The plugging cement slurry contains plant fibers and polypropylene high-temperature degradable particles.

4. The tail pipe consolidation process for heavy oil thermal recovery wells used in well repair operations according to claim 3, characterized in that: In the plugging cement slurry, the volume ratio of cement slurry: plant fiber: polypropylene high temperature degradation particles is 1:0.2:0.2, wherein the diameter of the polypropylene high temperature degradation particles is 3-6 mm.

5. The tail pipe consolidation process for heavy oil thermal recovery wells used in well repair operations according to claim 1, characterized in that: The formation pressure after plugging by the plugging cement slurry is not less than the system balance pressure during cementing, that is, P 地层承压 ≥P 平衡 +0.6.

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