Oil casing annulus pressure diagnosis method and device and medium

Abstract

The invention provides an oil casing annulus pressure diagnosis method and device and a medium, and relates to the technical field of oil field oil production engineering.The method comprises the steps that the pressure, temperature and temperature variation of a shaft are determined, and shaft units are divided; for each wellbore unit, determining a first annulus pressurization prediction value of the wellbore unit according to the temperature variation and a thermal expansion pressurization prediction model; for each shaft unit, determining a second annulus pressurization prediction value of the shaft unit according to the pressure, the temperature and the gas leakage pressurization prediction model; and according to the first annulus pressurization predicted value, the second annulus pressurization predicted value, the measured first annulus pressurization actual value and the measured second annulus pressurization actual value, diagnosing the reason for generating the annulus pressure of the oil casing. Therefore, the reason for the annulus pressure of the oil casing is determined through calculation, powerful reference and theoretical basis are provided for annulus pressure management and control and safe production, the requirement for efficient exploitation of an oil field is met, and the efficiency and convenience of efficient exploitation of the oil field are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oilfield production engineering, in particular to an oil casing annulus pressure diagnosis method, device and medium. BACKGROUND

[0002] The annulus pressure problem of the ultra-deep gas well is one of the serious challenges affecting the safe exploitation of oil and gas. The risk of annulus pressure has a wide consensus, such as causing serious downhole accidents such as tubing crushing or casing failure. Field pressure monitoring of ultra-deep gas wells shows that the tubing-casing annulus pressure is the most serious, and the main reasons for the annulus pressure include the thermal expansion of the fluid, the change of the annulus volume and the leakage of the fluid. Usually, the annulus pressure caused by the thermal expansion of the annulus fluid is inevitable, but due to the complexity of the engineering environment and operating conditions of the ultra-deep gas well, the gas leakage caused by the failure or performance degradation of the wellbore barrier assembly may also exist, which will increase the contribution of gas leakage to the annulus pressure, so that it is difficult to determine the reason for the tubing-casing annulus pressure of the ultra-deep gas well.

[0003] For the oil casing annulus, the safety barrier components mainly include the wellhead device, the tubing and the packer. In order to monitor the performance of the safety barrier components, it is usually necessary to carry out shut-in operation and lower the integrity monitoring tool for identification, which is difficult to meet the demand of efficient exploitation of oil field, so there is an urgent need for a calculation method to determine the reason for the annulus pressure, which provides a theoretical basis for the control measures of the oil casing annulus pressure.

[0004] In view of the problems of the prior art, the present application provides an oil casing annulus pressure diagnosis method, device and medium. SUMMARY

[0005] In view of the problems of the prior art, the present application provides an oil casing annulus pressure diagnosis method, device and medium, which comprises:

[0006] Determine the pressure, temperature and temperature change of the wellbore, and divide the wellbore unit;

[0007] For each wellbore unit, determine the first annulus pressure prediction value of the wellbore unit according to the temperature change and the thermal expansion pressure prediction model;

[0008] For each wellbore unit, determine the second annulus pressure prediction value of the wellbore unit according to the pressure, the temperature and the gas leakage pressure prediction model;

[0009] According to the first annulus pressure prediction value, the second annulus pressure prediction value, the measured first annulus pressure actual value and the second annulus pressure actual value, diagnose the reason for the oil casing annulus pressure.

[0010] According to one embodiment of the present application, the first annulus pressure boost prediction value is obtained by the following steps:

[0011] According to the temperature variation and the thermal expansion pressure boost prediction model, a first volume variation caused by radial thermal expansion of the tubing, a second volume variation caused by radial compression of the tubing, a third volume variation caused by thermal expansion of the annulus fluid, and a fourth volume variation caused by compression of the annulus fluid are determined;

[0012] According to the first volume variation, the second volume variation, the third volume variation, and the fourth volume variation, the first annulus pressure boost prediction value is determined.

[0013] According to one embodiment of the present application, the thermal expansion pressure boost prediction model comprises a first target formula and a second target formula;

[0014] The first volume variation is determined by the following steps:

[0015] According to the temperature variation and the first target formula, a radial displacement caused by radial thermal expansion of the tubing is determined;

[0016] According to the radial displacement and the second target formula, the first volume variation is determined.

[0017] The first target formula is:

[0018]

[0019] wherein u1 refers to a radial displacement caused by radial thermal expansion of the tubing, α1 refers to an expansion coefficient of the tubing, K -1 , ΔT refers to a temperature variation, μ refers to a Poisson's ratio, r to refers to an outer radius of the tubing, mm; r ti refers to an inner radius of the tubing, mm;

[0020] The second target formula is:

[0021]

[0022] wherein ΔV1 refers to the first volume variation; Δh refers to a length of a wellbore unit, m.

[0023] According to one embodiment of the present application, the thermal expansion pressure boost prediction model comprises a third target formula and a fourth target formula;

[0024] The second volume variation is determined by the following steps:

[0025] According to the temperature variation and the third target formula, a radial displacement caused by radial compression of the tubing is determined.

[0026] determining the second volume change amount according to the radial displacement and the fourth target formula;

[0027] The third target formula is:

[0028]

[0029] wherein u2 refers to the radial displacement caused by the radial compression of the oil pipe; Δp refers to the first annular pressure boosting prediction value, MPa; E refers to the elastic modulus of the oil pipe, MPa;

[0030] wherein Δp = (α / k)ΔT-ΔV ann / kV ann +ΔV L / kV L

[0031] α refers to the isothermal expansion coefficient of the annular fluid, K -1 ; k refers to the isothermal compression coefficient of the annular fluid, K -1 ; V ann refers to the annular volume, m 3 ; ΔV ann refers to the annular volume change amount, m 3 ; ΔV L refers to the fluid volume change amount caused by leakage, m 3 ; V L refers to the fluid volume caused by leakage, m 3 ;

[0032] The fourth target formula is:

[0033] ΔV2 = [π(r to +u1) 2 -(r to +u1-u2) 2 ]Δh

[0034] wherein ΔV2 refers to the second volume change amount.

[0035] According to one embodiment of the present application, the thermal expansion pressure boosting prediction model comprises a fifth target formula;

[0036] The third volume change amount is determined by the following steps:

[0037] The third volume change amount is determined according to the temperature change amount and the fifth target formula;

[0038] The fifth target formula is:

[0039]

[0040] Wherein, ΔV3 refers to the third volume change; α refers to the thermal expansion coefficient of annulus fluid; r ci R refers to the production casing outside radius, mm.

[0041] According to one embodiment of the present application, the thermal expansion boosting prediction model comprises a sixth target formula;

[0042] The fourth volume change is determined by the following steps:

[0043] According to the temperature change and the sixth target formula, the fourth volume change is determined;

[0044] The sixth target formula is:

[0045]

[0046] Wherein, ΔV4 refers to the fourth volume change.

[0047] According to one embodiment of the present application, the first annulus boosting prediction value is obtained by the following steps:

[0048] The first volume change, the second volume change, the third volume change and the fourth volume change are substituted into a seventh target formula to obtain a first annulus boosting prediction value;

[0049] The first annulus boosting prediction value is substituted into the thermal expansion boosting prediction model to obtain a second annulus boosting prediction value;

[0050] It is judged whether the difference between the first annulus boosting prediction value and the second annulus boosting prediction value is not greater than a first target threshold; if the difference is not greater than the first target threshold, iteration is terminated, and the first annulus boosting prediction value is determined as the first annulus boosting prediction value; if the difference is greater than the first target threshold, the second annulus boosting prediction value is assigned as the first annulus boosting prediction value, which is substituted into the thermal expansion boosting prediction model until the difference is less than the first target threshold;

[0051] The seventh target formula is:

[0052] ΔV2+ΔV3=ΔV1+ΔV4

[0053] Wherein, ΔV1 refers to the first volume change; ΔV2 refers to the second volume change; ΔV3 refers to the third volume change; ΔV4 refers to the fourth volume change.

[0054] According to one embodiment of the present application, the gas leakage boosting prediction model comprises an eighth target formula and a ninth target formula;

[0055] The second annulus boosting prediction value is determined by the following steps:

[0056] acquiring the pressure at the leakage outlet;

[0057] determining the fluid state at the leakage outlet according to the pressure at the leakage outlet and the pressure, to further determine the volumetric flow of the gas leakage;

[0058] determining the volume of the gas leakage according to the volumetric flow and the eighth target formula;

[0059] determining the second annulus pressure build-up prediction value according to the volume of the gas leakage and the ninth target formula.

[0060] According to one embodiment of the present application, the eighth target formula is:

[0061]

[0062] wherein Q g is the volume of the gas leakage in the time period from t o to t, m 3 ; v g is the volumetric flow of the gas leakage, m 3 / s.

[0063] The ninth target formula is:

[0064]

[0065] wherein Δp2 is the second annulus pressure build-up prediction value, MPa, k is the isothermal compressibility of the annulus fluid, K -1 ; V ann is the annulus volume, m 3 .

[0066] According to one embodiment of the present application, the cause of the annulus pressure build-up of the oil casing is diagnosed by the following steps:

[0067] the value obtained by dividing the difference between the first annulus pressure build-up prediction value and the first annulus pressure build-up actual value by the first annulus pressure build-up actual value is determined as the first accuracy;

[0068] the value obtained by dividing the difference between the second annulus pressure build-up prediction value and the second annulus pressure build-up actual value by the second annulus pressure build-up actual value is determined as the second accuracy;

[0069] if the first accuracy is not less than a second target threshold and the second accuracy is not less than the second target threshold, the cause of the annulus pressure build-up of the oil casing is diagnosed as thermal expansion;

[0070] If the first accuracy is less than the second target threshold or the second accuracy is less than the second target threshold, the cause of the casing annulus pressure build-up is diagnosed as thermal expansion and leakage.

[0071] According to one embodiment of the present application, the temperature, pressure and temperature change of the wellbore are determined by the following steps:

[0072] Obtaining wellbore target parameters; the wellbore target parameters include wellbore structure parameters, material physical parameters and annulus fluid parameters;

[0073] Inputting the wellbore target parameters into a wellbore heat transfer model to output the temperature and pressure of the wellbore;

[0074] According to the temperature change of the wellbore, the temperature change of the wellbore is determined.

[0075] According to another aspect of the present application, a storage medium containing a series of instructions for executing the method steps of any one of the above is also provided.

[0076] According to another aspect of the present application, an oil casing annulus pressure diagnosis device is also provided, which executes the method of any one of the above, and the device comprises:

[0077] A first determination module for determining the pressure, temperature, temperature change of the wellbore, and dividing the wellbore unit;

[0078] A second determination module for determining, for each wellbore unit, a first annulus pressure prediction value of the wellbore unit according to the temperature change and a thermal expansion pressure prediction model;

[0079] A third determination module for determining, for each wellbore unit, a second annulus pressure prediction value of the wellbore unit according to the pressure, the temperature and a gas leakage pressure prediction model;

[0080] A diagnosis module for diagnosing the cause of the casing annulus pressure build-up according to the first annulus pressure prediction value, the second annulus pressure prediction value, a measured first annulus pressure actual value and a second annulus pressure actual value.

[0081] The present application provides an oil casing annulus pressure diagnosis method, device and medium, which has the following advantages compared with the prior art:

[0082] The present application can calculate the first annulus pressure prediction value and the second annulus pressure prediction value of the wellbore unit through the thermal expansion pressure prediction model and the gas leakage pressure prediction model, and then combine the first annulus pressure actual value and the second annulus pressure actual value to diagnose the cause of the annulus pressure generation. In this way, the cause of the casing annulus pressure generation is determined by calculation, which provides a strong reference and theoretical basis for annulus pressure control and safety production, and ensures the reliability of the gas well barrier. At the same time, personnel do not need to go down the well to use monitoring tools to identify the cause of the casing annulus pressure, which realizes the needs of oilfield efficient exploitation, improves the efficiency and convenience of oilfield efficient exploitation, avoids the risk of going down the well under high temperature and high pressure, and in addition, the two models integrate real gas thermodynamics into the control equation, which improves the prediction accuracy.

[0083] Other features and advantages of the present application will be set forth in the following specification, and in part will be apparent from the description, or can be learned by practice of the present application. The objects and other advantages of the present application will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0084] The accompanying drawings are included to provide a further understanding of the present application and are incorporated in and constitute a part of this specification, illustrate embodiments of the present application and together with the description serve to explain the present application, and do not limit the present application. In the drawings:

[0085] Figure 1 A flow chart of a casing annulus pressure diagnosis method according to an embodiment of the present application is shown;

[0086] Figure 2 A schematic diagram of a pressure monitoring change curve of an ultra-deep gas well during production according to an embodiment of the present application is shown;

[0087] Figure 3 A temperature distribution curve corresponding to the wellbore under different chokes according to an embodiment of the present application is shown;

[0088] Figure 4 A pressure distribution curve corresponding to the wellbore under different chokes according to an embodiment of the present application is shown;

[0089] Figure 5 A schematic diagram of the first annulus pressure prediction value of the annulus fluid under the condition of considering the nonlinear property and under the condition of not considering the nonlinear property according to an embodiment of the present application is shown;

[0090] Figure 6 A schematic diagram of the second annulus pressure prediction value of the leakage point at different depths according to an embodiment of the present application is shown;

[0091] Figure 7A block diagram of a casing annulus pressure diagnosis device according to an embodiment of the present application is shown.

[0092] In the drawings, the same components are designated by the same reference numerals. In addition, the drawings are not drawn to scale. DETAILED DESCRIPTION

[0093] In order to make the objects, technical solutions and advantages of the present application clearer, the embodiments of the present application are further described in detail below with reference to the drawings.

[0094] In view of the above defects of the prior art, the present application provides a casing annulus pressure diagnosis method, device and medium.

[0095] Figure 1 A flowchart of a casing annulus pressure diagnosis method according to an embodiment of the present application is shown, the method comprising:

[0096] S101, determining the pressure, temperature and temperature change of the wellbore, and dividing the wellbore unit;

[0097] S102, for each wellbore unit, determining the first annulus pressure prediction value of the wellbore unit according to the temperature change and the thermal expansion pressure prediction model;

[0098] S103, for each wellbore unit, determining the second annulus pressure prediction value of the wellbore unit according to the pressure, temperature and gas leakage pressure prediction model;

[0099] S104, diagnosing the cause of the casing annulus pressure generation according to the first annulus pressure prediction value, the second annulus pressure prediction value, the measured first annulus pressure actual value and the second annulus pressure actual value.

[0100] As shown in Figure 2 , it is a pressure monitoring change curve of a certain super-deep gas well in northwest China during production. As can be seen from Figure 2 , the casing annulus pressure presents three sections of pressure rise characteristics during the process of adjusting the size of the choke to increase the yield, so the wellbore can be divided into three wellbore units according to the size of the choke, that is, the wellbore unit is a section of the wellbore, in order to analyze the cause of the annulus pressure generation of each wellbore unit.

[0101] As shown in Figure 3 and Figure 4 , they are the temperature and pressure distribution curves of the wellbore corresponding to different chokes. As can be seen from Figure 3 and Figure 4 , the temperature value, temperature change and pressure corresponding to each wellbore unit can be obtained. Figure 3 and Figure 4 As can be seen from , the temperature of the wellbore is gradually increasing, and the pressure of the wellbore is gradually increasing.

[0102] In order to reveal the annulus pressure change mechanism, considering the fluid thermal expansion effect and gas leakage, according to the established thermal expansion pressure prediction model and the gas leakage pressure prediction model, the annulus pressure value is predicted, and then compared with the actual monitoring value, so as to identify the reason of the annulus pressure in the ultra-deep gas well.

[0103] The first annulus pressure prediction value and the second annulus pressure prediction value of the wellbore unit can be calculated by the thermal expansion pressure prediction model and the gas leakage pressure prediction model, and then the first annulus pressure actual value and the second annulus pressure actual value are combined to diagnose the reason of the annulus pressure. In this way, the reason of the casing annulus pressure is determined by calculation, which provides a strong reference and theoretical basis for annulus pressure control and safety production, and ensures the reliability of the gas well barrier. At the same time, personnel is not required to go down the well to use monitoring tools to identify the reason of the casing annulus pressure, which realizes the demand of oilfield efficient exploitation, improves the efficiency and convenience of oilfield efficient exploitation, avoids the risk of going down the well under high temperature and high pressure, and in addition, the two models integrate the real gas thermodynamics into the control equation, which improves the prediction accuracy.

[0104] In a possible embodiment, the first annulus pressure prediction value is obtained by the following steps:

[0105] According to the temperature change amount and the thermal expansion pressure prediction model, the first volume change amount caused by the radial thermal expansion of the oil pipe, the second volume change amount caused by the radial compression of the oil pipe, the third volume change amount caused by the thermal expansion of the annulus fluid and the fourth volume change amount caused by the compression of the annulus fluid are determined;

[0106] According to the first volume change amount, the second volume change amount, the third volume change amount and the fourth volume change amount, the first annulus pressure prediction value is determined.

[0107] According to the temperature change amount and the thermal expansion pressure prediction model, the first volume change amount caused by the radial thermal expansion of the oil pipe, the second volume change amount caused by the radial compression of the oil pipe, the third volume change amount caused by the thermal expansion of the annulus fluid and the fourth volume change amount caused by the compression of the annulus fluid are determined;

[0108]

[0109] By Figure 3 And Figure 4It can be seen that the temperature of the wellbore is gradually increasing. Ignoring the leakage, considering the thermal expansion of the fluid and the change of the annulus volume, it can be seen that the tubing and the annulus fluid will cause thermal expansion due to the temperature rise of the wellbore, thereby causing the volume to change, and the annulus pressure will also rise due to the temperature rise of the wellbore, thereby causing compression and volume change.

[0110] Without temperature change, the relationship between the pressure in the tubing-casing annulus can be directly studied by applying and releasing the tubing-casing annulus pressure.

[0111] In this way, the thermal expansion pressure prediction model can be used to determine the first annulus pressure prediction value by the volume change. The accuracy and precision of the first annulus pressure prediction value are improved, and the basis for determining the cause of the annulus pressure is provided.

[0112] In one possible embodiment, the thermal expansion pressure prediction model comprises a first target formula and a second target formula;

[0113] The first volume change amount is determined by the following steps:

[0114] According to the temperature change amount and the first target formula, the radial displacement caused by the radial thermal expansion of the tubing is determined;

[0115] According to the radial displacement and the second target formula, the first volume change amount is determined;

[0116] The first target formula is:

[0117]

[0118] Wherein, u1 refers to the radial displacement caused by the radial thermal expansion of the tubing, a1 refers to the expansion coefficient of the tubing, K -1 , ΔT refers to the temperature change amount, μ refers to the Poisson's ratio, r to refers to the outer radius of the tubing, mm; r ti refers to the inner radius of the tubing, mm;

[0119] The second target formula is:

[0120]

[0121] Wherein, ΔV1 refers to the first volume change amount; Δh refers to the length of the wellbore unit, m.

[0122] The first volume change amount is a decrease. The tubing will have a radial thermal expansion due to the temperature increase of the wellbore unit, thereby causing a radial displacement, which can be obtained by Formula 2. Then, the radial displacement of the tubing will cause a volume change amount of the tubing, which can be obtained by Formula 3. In this way, according to the temperature change amount of the wellbore unit, the first target formula and the second target formula, the first volume change amount of the tubing can be determined, the accuracy of the first volume change amount is improved, and the basis for determining the annulus pressure boosting reason is improved.

[0123] In a possible embodiment, the thermal expansion pressure boosting prediction model comprises a third target formula and a fourth target formula.

[0124] The second volume change amount is determined by the following steps:

[0125] According to the temperature change amount and the third target formula, a radial displacement caused by the radial compression of the tubing is determined.

[0126] According to the radial displacement and the fourth target formula, the second volume change amount is determined.

[0127] The third target formula is:

[0128]

[0129] wherein u2 represents the radial displacement caused by the radial compression of the tubing; Δp represents the first annulus pressure boosting prediction value, MPa; E represents the elastic modulus of the tubing, MPa;

[0130] wherein Δp = (α / k)ΔT-ΔV ann / kV ann +ΔV L / kV L Formula 5

[0131] α represents the isothermal expansion coefficient of the annulus fluid, K -1 ; k represents the isothermal compression coefficient of the annulus fluid, K -1 ; V ann represents the annulus volume, m 3 ; ΔV ann represents the annulus volume change amount, m 3 ; ΔV L represents the fluid volume change amount caused by leakage, m 3 ; V L represents the fluid volume caused by leakage, m 3 ;

[0132] The fourth target formula is:

[0133] ΔV2 = [π(r to +u1) 2 -(rto +u1-u2) 2 ]Δh Formula 6

[0134] wherein, ΔV2 refers to the second volume change amount.

[0135] wherein, the second volume change amount is an increase amount, and the annulus pressure initial value is 0. It can be known from Formula 5 that the wellbore temperature rise will cause the annulus pressure to rise, the annulus pressure rise will cause the radial compression of the tubing, and thus the radial displacement, and the radial displacement of the tubing caused by the radial compression can be obtained from Formula 4. The radial displacement will cause the volume change, and the second volume change amount can be obtained from Formula 6. In this way, according to the temperature change amount of the wellbore unit, the third target formula and the fourth target formula, the second volume change amount of the tubing can be determined, the accuracy of the second volume change amount is improved, and the basis for determining the annulus pressure boosting reason is improved.

[0136] In a possible embodiment, the thermal expansion pressure boosting prediction model comprises a fifth target formula;

[0137] The third volume change amount is determined by the following steps:

[0138] According to the temperature change amount and the fifth target formula, the third volume change amount is determined.

[0139] The fifth target formula is:

[0140]

[0141] wherein, ΔV3 refers to the third volume change amount; a refers to the annulus fluid thermal expansion coefficient; r ci refers to the production casing outer radius, mm.

[0142] Similarly, the annulus fluid will also have thermal expansion effect due to the temperature rise, thus causing the volume change, and the third volume change amount can be obtained from Formula 7. In this way, according to the temperature change amount of the wellbore unit and the fifth target formula, the third volume change amount of the tubing can be determined, the accuracy of the third volume change amount is improved, and the basis for determining the annulus pressure boosting reason is improved.

[0143] In a possible embodiment, the thermal expansion pressure boosting prediction model comprises a sixth target formula;

[0144] The fourth volume change amount is determined by the following steps:

[0145] According to the temperature change amount and the sixth target formula, the fourth volume change amount is determined.

[0146] The sixth target formula is:

[0147]

[0148] Wherein, ΔV4 refers to the fourth volume change amount.

[0149] Likewise, the annulus fluid will also be compressed due to the increase in annulus pressure, thereby generating a volume change, and the fourth volume change amount can be obtained from equation 8. Thus, according to the temperature change amount of the wellbore unit and the sixth target formula, the fourth volume change amount of the tubing can be determined, improving the accuracy of the fourth volume change amount and providing a basis for determining the annulus pressure boosting reason.

[0150] In a possible embodiment, the first annulus pressure boosting prediction value is obtained by the following steps:

[0151] The first volume change amount, the second volume change amount, the third volume change amount and the fourth volume change amount are substituted into the seventh target formula to obtain the first annulus pressure boosting estimation value;

[0152] The first annulus pressure boosting estimation value is substituted into the thermal expansion pressure boosting prediction model to obtain the second annulus pressure boosting estimation value;

[0153] It is judged whether the difference between the first annulus pressure boosting estimation value and the second annulus pressure boosting estimation value is not greater than the first target threshold value; if the difference is not greater than the first target threshold value, the iteration is terminated, and the first annulus pressure boosting estimation value is determined as the first annulus pressure boosting prediction value; if the difference is greater than the first target threshold value, the second annulus pressure boosting estimation value is assigned to the first annulus pressure boosting estimation value, and the thermal expansion pressure boosting prediction model is substituted again until the difference is less than the first target threshold value;

[0154] Wherein, the seventh target formula is:

[0155] ΔV2+ΔV3=ΔV1+ΔV4 Equation 9

[0156] Wherein, ΔV1 refers to the first volume change amount; ΔV2 refers to the second volume change amount; ΔV3 refers to the third volume change amount; and ΔV4 refers to the fourth volume change amount.

[0157] For example, the first target threshold value can be determined according to the actual application scenario, which is not limited in the present application.

[0158] According to the compatibility of the annulus volume, the balance of the annulus volume can be expressed as formula 9. According to formula 9, the first annulus pressure increase estimate Δp' can be obtained. In order to improve the accuracy of the first annulus pressure increase estimate, the first annulus pressure increase estimate can be re-substituted into formulas 2 to 9 to obtain a second annulus pressure increase estimate Δp''; Δp' and Δp'' are compared, and if the set calculation accuracy (the difference between the first annulus pressure increase estimate and the second annulus pressure increase estimate is less than or equal to the first target threshold) is reached, Δp' is the first annulus pressure increase estimate under this iteration; if the set calculation accuracy (the difference between the first annulus pressure increase estimate and the second annulus pressure increase estimate is greater than the first target threshold) is not reached, Δp' = Δp'' and the calculation is re-substituted into the thermal expansion pressure increase prediction model until the accuracy requirement is met, and the calculation result is output. In this way, by comparing the difference between the first annulus pressure increase estimate and the second annulus pressure increase estimate with the first target threshold, the calculation accuracy of the first annulus pressure increase estimate is ensured, and the accuracy of the first annulus pressure increase estimate is improved.

[0159] In one possible embodiment, the gas leakage pressure increase prediction model includes an eighth target formula and a ninth target formula.

[0160] The second annulus pressure increase estimate is determined by the following steps:

[0161] The pressure at the leakage outlet is obtained.

[0162] According to the pressure at the leakage outlet and the pressure, the fluid state at the leakage outlet is determined to further determine the volumetric flow rate of the gas leakage.

[0163] According to the volumetric flow rate and the eighth target formula, the volume of the gas leakage is determined.

[0164] According to the volume of the gas leakage and the ninth target formula, the second annulus pressure increase estimate is determined.

[0165] For example, the critical pressure ratio of the gas leakage can be determined according to the pressure at the leakage outlet, the pressure of the wellbore, and formula 10, and then the result of dividing the pressure at the leakage outlet by the pressure of the wellbore is compared with the critical pressure ratio to determine the fluid state at the leakage outlet.

[0166]

[0167] wherein CPR is the critical pressure ratio, k g is the heat transfer coefficient of the gas.

[0168] If the result of dividing the pressure at the leakage outlet by the wellbore pressure is greater than or equal to the critical pressure ratio, the fluid state at the leakage outlet is a subcritical leakage state; if the result of dividing the pressure at the leakage outlet by the wellbore pressure is less than the critical pressure ratio, the fluid state at the leakage outlet is a critical leakage state.

[0169] Then, the volume flow rate of the gas leakage, i.e., the gas leakage rate, can be determined according to the corresponding formula 11 in the subcritical leakage state:

[0170]

[0171] wherein v g represents the volume flow rate of the gas leakage, m 3 / s; C d represents the orifice flow coefficient; A o represents the cross-sectional area of the leakage hole, mm 2 ; M represents the molar mass of the gas, kg / mol; Z represents the gas compressibility factor; R represents the gas constant; P d represents the pressure at the leakage outlet, MPa; P u represents the pressure of the wellbore, MPa; T u represents the temperature of the wellbore, K; k g represents the heat transfer coefficient of the gas; p g represents the density of the gas, kg / m 3 .

[0172] The volume flow rate of the gas leakage can also be determined according to the corresponding formula 12 in the critical leakage state, in which case the volume flow rate of the gas leakage remains unchanged.

[0173]

[0174] wherein the volume of the gas leakage is the integral of the leakage rate and time, so the volume of the gas leakage can be determined according to the eighth target formula, and the second annulus pressure boosting prediction value can be determined according to the ninth target formula based on the interaction relationship between the leakage volume and the annulus pressure. In this way, the accuracy of the second annulus pressure boosting prediction value is improved.

[0175] In one possible embodiment, the eighth target formula is:

[0176]

[0177] wherein Q g is the volume of the gas leakage in the time from t o to t, m 3 ; v g represents the volume flow rate of the gas leakage, m 3 / s;

[0178] The ninth target formula is:

[0179]

[0180] Wherein, Δp2 refers to the second annulus pressure increase prediction value, MPa, k refers to the isothermal compression coefficient of the annulus fluid, K -1 ; V ann refers to the annulus volume, m 3 .

[0181] In a possible embodiment, the cause of the oil casing annulus pressure generation is diagnosed by the following steps:

[0182] The value obtained by dividing the difference between the first annulus pressure increase prediction value and the first annulus pressure increase actual value by the first annulus pressure increase actual value is determined as the first accuracy;

[0183] The values obtained by dividing the differences between the second annulus pressure increase prediction value and the second annulus pressure increase actual value by the second annulus pressure increase actual value are respectively determined as the second accuracy;

[0184] If the first accuracy is not less than the second target threshold and the second accuracy is not less than the second target threshold, the cause of the oil casing annulus pressure generation is diagnosed as thermal expansion;

[0185] If the first accuracy is less than the second target threshold or the second accuracy is less than the second target threshold, the cause of the oil casing annulus pressure generation is diagnosed as thermal expansion and leakage.

[0186] For example, the second target threshold can be determined according to the actual application scene, and the present application sets it to 90%. As Figure 5 shown, the first annulus pressure prediction values of the annulus fluid under the condition of considering the nonlinear property and under the condition of not considering the nonlinear property are shown, wherein, the prediction value 1 is the value without considering the nonlinear property of the fluid; and the prediction value 2 is the value considering the nonlinear property of the fluid. It can be known from Figure 5 that the maximum error under the condition of considering the nonlinear property of the fluid is 7.97%, that is, the minimum value of the first accuracy under the condition of considering the nonlinear property of the fluid is 92.03%, and the maximum error under the condition of not considering the nonlinear property of the fluid is 11.85%, that is, the minimum value of the first accuracy under the condition of not considering the nonlinear property of the fluid is 88.15%. As Figure 6 shown, the second annulus pressure prediction values corresponding to the leakage points at different depths are shown. Then, the second accuracy can be calculated and whether the second accuracy is less than the second target threshold can be judged to comprehensively diagnose the cause of the annulus pressure generation, so that the accuracy of the cause of the annulus pressure generation is improved.

[0187] In a possible embodiment, the temperature, pressure and temperature change amount of the wellbore are determined by the following steps:

[0188] Acquire wellbore target parameters; the wellbore target parameters include: wellbore structure parameters, material physical property parameters and annular fluid parameters;

[0189] Input the wellbore target parameters into a wellbore heat transfer model, and output the temperature and pressure of the wellbore;

[0190] According to the temperature change of the wellbore, the temperature change amount of the wellbore is determined.

[0191] For example, the wellbore heat transfer model can be determined by the existing mode. After obtaining the temperature and pressure of the wellbore, the measured temperature and pressure can be verified to ensure the accuracy of the temperature and pressure, and provide a basis for subsequent determination of the annular pressure carrying reason.

[0192] The oil casing annular pressure diagnosis method provided by the application can also be matched with a computer readable storage medium, and the computer program is stored on the storage medium. The computer program can run computer instructions, and the computer instructions include computer program codes, which can be in the form of source code, object code, executable files or some intermediate forms.

[0193] The computer readable storage medium can include any entity or device capable of carrying computer program codes, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium, etc.

[0194] It should be noted that the content contained in the computer readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction, for example, in some jurisdictions, according to legislation and patent practice, the computer readable storage medium does not include electrical carrier signals and telecommunication signals.

[0195] According to another aspect of the application, an oil casing annular pressure diagnosis device is also provided, which executes an oil casing annular pressure diagnosis method, Figure 7 is a block diagram of an oil casing annular pressure diagnosis device provided by an embodiment of the application, as shown in Figure 7 The device comprises:

[0196] The first determination module 510 is configured to determine the pressure, temperature, temperature change amount of the wellbore, and divide the wellbore unit;

[0197] The second determination module 520 is configured to, for each wellbore unit, determine the first annular pressure prediction value of the wellbore unit according to the temperature change amount and the thermal expansion pressure prediction model.

[0198] The third determination module 530 is configured to determine, for each wellbore unit, a second annulus pressure boosting prediction value of the wellbore unit according to the pressure, the temperature, and the gas leakage pressure boosting prediction model.

[0199] The diagnosis module 540 is configured to diagnose the cause of the casing annulus pressure based on the first annulus pressure boosting prediction value, the second annulus pressure boosting prediction value, the measured first annulus pressure boosting actual value, and the measured second annulus pressure boosting actual value.

[0200] In summary, the present application provides an oil casing annulus pressure diagnosis method, device and medium, which has the following advantages compared with the prior art:

[0201] The present application can calculate the first annulus pressure boosting prediction value and the second annulus pressure boosting prediction value of the wellbore unit through the thermal expansion pressure boosting prediction model and the gas leakage pressure boosting prediction model, and then combine the first annulus pressure boosting actual value and the second annulus pressure boosting actual value to diagnose the cause of the casing annulus pressure. In this way, the cause of the casing annulus pressure is determined by calculation, which provides a strong reference and theoretical basis for casing annulus pressure control and safety production, and ensures the reliability of the gas well barrier. At the same time, personnel do not need to go down the well to use monitoring tools to identify the cause of the casing annulus pressure, which realizes the demand for efficient oilfield exploitation, improves the efficiency and convenience of efficient oilfield exploitation, avoids the risk of going down the well under high temperature and high pressure, and in addition, the two models integrate real gas thermodynamics into the control equation, improving the prediction accuracy.

[0202] It should be understood that the embodiments disclosed herein are not limited to the specific structure, processing steps or materials disclosed herein, but extend to equivalent alternatives of these features understood by those skilled in the relevant art. It should also be understood that the terms used herein are for the purpose of describing specific embodiments only and are not intended to be limiting.

[0203] In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more; the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" and the like are only for the purpose of description and cannot be understood as indicating or implying relative importance.

[0204] In the description of the present application, it is necessary to point out that, unless explicitly defined and limited, the terms "connected", "connection" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0205] Certain terms are used throughout the present application to refer to particular system components. As one skilled in the art will appreciate, the same component can be referred to by different names and can not be referred to at all, depending on the specific embodiment. In this disclosure, the terms "comprise", "comprising", and "comprises" are used in an open-ended fashion, and thus should be interpreted to mean "including, but not limited to...". Also, the term "couple" or "coupled" as can be used herein, includes the joining of two components by a direct connection, and also the joining through an additional component, element, circuit, or module, where the additional component does not modify the information of the coupled components. Indirect coupling (e.g., via an additional component) that does modify the information of the coupled components is also within the scope of the term "coupled".

[0206] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. Thus, the appearances of the phrases "in one embodiment" or "an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.

[0207] Embodiments of the present application are presented by way of example and not limitation. Many modifications and variations of the present application are possible in light of the above teachings. The embodiments were chosen and described in order to best explain the principles of the present application and its practical application and to thereby enable others skilled in the art to best utilize the present application in various embodiments and with various modifications as are suited to the particular use contemplated.

[0208] Although the disclosed embodiments of the present application are as above, the above description is only for the purpose of facilitating understanding of the present application and is not intended to limit the present application. Any person skilled in the art of the present application can make any modification and change in the implementation form and details without departing from the spirit and scope of the present application, but the patent protection scope of the present application shall be subject to the scope defined by the appended claims.

Claims

1. A method of diagnosing casing annulus pressure loading, comprising: The method comprises: determining pressure, temperature, temperature change of the wellbore, and dividing the wellbore unit; for each wellbore unit, determining a first annulus pressure increase prediction value of the wellbore unit according to the temperature change and a thermal expansion pressure increase prediction model; for each wellbore unit, determining a second annulus pressure increase prediction value of the wellbore unit according to the pressure, the temperature and a gas leakage pressure increase prediction model; diagnosing the cause of the casing annulus pressure according to the first annulus pressure increase prediction value, the second annulus pressure increase prediction value, a measured first annulus pressure increase actual value and a second annulus pressure increase actual value.

2. The method of claim 1, wherein, The first annulus pressure increase prediction value is obtained by the following steps: determining a first volume change amount due to radial thermal expansion of the tubing, a second volume change amount due to radial compression of the tubing, a third volume change amount due to thermal expansion of the annulus fluid and a fourth volume change amount due to compression of the annulus fluid according to the temperature change and the thermal expansion pressure increase prediction model; determining the first annulus pressure increase prediction value according to the first volume change amount, the second volume change amount, the third volume change amount and the fourth volume change amount.

3. The method of claim 2, wherein, The thermal expansion pressure increase prediction model comprises a first target formula and a second target formula; The first volume change amount is determined by the following steps: determining a radial displacement due to radial thermal expansion of the tubing according to the temperature change and the first target formula; determining the first volume change amount according to the radial displacement and the second target formula; The first target formula is: Wherein, u1 refers to the radial displacement generated by the radial thermal expansion of the oil pipe, a1 refers to the expansion coefficient of the oil pipe, K -1 , ΔT refers to the temperature change, μ refers to the Poisson's ratio, r to refers to the outer radius of the oil pipe, mm; r ti refers to the inner radius of the oil pipe, mm; The second target formula is: wherein ΔV1 refers to the first volume change amount; Δh refers to the length of the wellbore unit, m.

4. The method of claim 3, wherein, The thermal expansion pressure increase prediction model comprises a third target formula and a fourth target formula; The second volume change amount is determined by the following steps: determining a radial displacement due to radial compression of the tubing according to the temperature change and the third target formula; determining the second volume change amount according to the radial displacement and the fourth target formula; The third target formula is: wherein u2 refers to the radial displacement due to radial compression of the tubing; Δp refers to the first annulus pressure increase prediction value, MPa; E refers to the elastic modulus of the tubing, MPa; where Δp = (a / k)ΔT - ΔV ann / kV ann +ΔV L / kV L a is the isothermal expansion coefficient of the annulus fluid, K -1 k is the isothermal compression coefficient of the annulus fluid, K -1 V ann is the annulus volume, m 3 AV ann is the annulus volume change, m 3 AV L is the fluid volume change due to leakage, m 3 V L is the fluid volume due to leakage, m 3 ​ The fourth target formula is: AV2 = [π(r to + u1) 2 - (r to + u1 - u2) 2 ] Ah wherein ΔV2 refers to the second volume change amount.

5. The method of claim 4, wherein, The thermal expansion pressure increase prediction model comprises a fifth target formula; The third volume change amount is determined by the following steps: determining the third volume change amount according to the temperature change and the fifth target formula; The fifth target formula is: Wherein, ΔV3 refers to the third volume change; α refers to the annulus fluid thermal expansion coefficient; r ci R refers to the production casing outside radius, mm.

6. The method of claim 5, wherein, The thermal expansion pressure increase prediction model comprises a sixth target formula; The fourth volume change amount is determined by the following steps: determining the fourth volume change amount according to the temperature change and the sixth target formula; The sixth target formula is: wherein ΔV4 refers to the fourth volume change amount.

7. The method of any one of claims 2-6, wherein, The first annulus pressure increase prediction value is obtained by the following steps: substituting the first volume change amount, the second volume change amount, the third volume change amount and the fourth volume change amount into a seventh target formula to obtain the first annulus pressure increase prediction value; The first annulus pressure boost estimation value is substituted into the thermal expansion pressure boost prediction model to obtain a second annulus pressure boost estimation value; It is judged whether the difference between the first annulus pressure boost estimation value and the second annulus pressure boost estimation value is not greater than a first target threshold value; If the difference is not greater than the first target threshold value, the iteration is terminated, and the first annulus pressure boost estimation value is determined as the first annulus pressure boost prediction value; if the difference is greater than the first target threshold value, the second annulus pressure boost estimation value is assigned as the first annulus pressure boost estimation value, and is substituted into the thermal expansion pressure boost prediction model again until the difference is less than the first target threshold value; The seventh target formula is: ΔV2+ΔV3=ΔV1+ΔV4 Wherein, ΔV1 refers to a first volume change amount; ΔV2 refers to a second volume change amount; ΔV3 refers to a third volume change amount; and ΔV4 refers to a fourth volume change amount.

8. The method of any one of claims 1-7, wherein, The gas leakage pressure boost prediction model comprises an eighth target formula and a ninth target formula; The second annulus pressure boost prediction value is determined by the following steps: The pressure at a leakage outlet is obtained; According to the pressure at the leakage outlet and the pressure, the fluid state at the leakage outlet is determined to further determine the volume flow rate of gas leakage; According to the volume flow rate and the eighth target formula, the volume of gas leakage is determined; According to the volume of gas leakage and the ninth target formula, the second annulus pressure boost prediction value is determined.

9. The method of claim 8, wherein, The eighth target formula is: wherein Q g is the volume of gas leaked during the time from t o to t 3 ; v g is the volumetric flow rate of gas leaked, m 3 / s; The ninth target formula is: Wherein, Δp2 refers to the second annulus pressure boost prediction value, MPa, k refers to the isothermal compression coefficient of the annulus fluid, K -1 ; V ann refers to the annulus volume, m 3 .

10. The method as claimed in any one of claims 1 to 9, characterized by, The cause of the oil casing annulus pressure is diagnosed by the following steps: The value obtained by dividing the difference between the first annulus pressure boost prediction value and the first annulus pressure boost actual value by the first annulus pressure boost actual value is determined as a first accuracy; The values obtained by dividing the differences between the second annulus pressure boost prediction value and the second annulus pressure boost actual value respectively by the second annulus pressure boost actual value are determined as a second accuracy; If the first accuracy is not less than a second target threshold value and the second accuracy is not less than the second target threshold value, it is diagnosed that the cause of the oil casing annulus pressure is thermal expansion; If the first accuracy is less than the second target threshold value or the second accuracy is less than the second target threshold value, it is diagnosed that the cause of the oil casing annulus pressure is thermal expansion and leakage.

11. The method of any one of claims 1-10, wherein, The temperature, pressure and temperature change amount of the wellbore are determined by the following steps: Obtaining wellbore target parameters; the wellbore target parameters comprise wellbore structure parameters, material physical property parameters and annulus fluid parameters; The wellbore target parameters are input into a wellbore heat transfer model to output the temperature and pressure of the wellbore; According to the temperature change of the wellbore, the temperature change amount of the wellbore is determined.

12. A storage medium, characterized by It comprises a series of instructions for executing the method steps of any one of claims 1-11.

13. A device for diagnosing casing annulus pressure, characterized in that, The device comprises: A first determination module for determining the pressure, temperature, temperature change amount of the wellbore, and dividing the wellbore unit; A second determination module for determining, for each wellbore unit, the first annulus pressure boost prediction value of the wellbore unit according to the temperature change amount and the thermal expansion pressure boost prediction model; a third determining module configured to determine, for each wellbore unit, a second annulus pressure buildup prediction value of the wellbore unit according to the pressure, the temperature, and a gas leakage pressure buildup prediction model; a diagnosing module configured to diagnose a cause of the oil casing annulus pressure buildup according to the first annulus pressure buildup prediction value, the second annulus pressure buildup prediction value, a measured first annulus pressure buildup actual value, and a second annulus pressure buildup actual value.

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