Prediction method and device for pre-drilling overpressure top surface depth of exploration well

Abstract

The invention relates to a method and device for predicting the pre-drilling overpressure top surface depth of an exploration well, and the method comprises the steps: collecting the formation pressure test data of a drilled well in a research region, and enabling the data to comprise a plurality of formation pressure test points of the drilled well; acquiring a density curve of the exploration well; according to the density curve of the exploration well, the overlying strata pressure PO of the exploration well and the hydrostatic pressure P hydrostatic of the exploration well are calculated; and according to the overlying stratum pressure PO of the exploration well, the hydrostatic pressure P hydrostatic of the exploration well and the multiple drilled stratum pressure test points, the pre-drilling overpressure top surface depth HTOP of the exploration well is obtained. The invention relates to a method for predicting the depth of an overpressure top surface before drilling of an exploration well, which is characterized in that analysis is carried out by utilizing the trend that the density changes along with the burial depth and the pressure test data of a drilled well formation, the uncertainty caused by predicting the overpressure top surface only depending on the formation speed is avoided, and the accuracy of predicting the overpressure top surface before drilling of the exploration well is improved.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum exploration, and in particular to a method and a device for predicting the depth of an overpressure top surface before drilling an exploration well. Background Art

[0002] The overpressure top is the top boundary of an abnormally high pressure area in an underground formation. Below this depth, the fluid pressure in the formation is significantly higher than the normal formation pressure. Identifying the overpressure top is very important for oil and gas exploration, because overpressure can significantly affect the safety and efficiency of drilling operations, and if overpressure is not correctly predicted and handled, it can lead to dangerous situations such as blowouts.

[0003] In the current research on the prediction of the overpressure top surface before drilling exploration wells, the seismic layer velocity characteristics are usually used to predict the depth of the overpressure top surface. However, since it is difficult to obtain accurate formation velocity data before drilling, the prediction results of the overpressure top surface depth before drilling exploration wells are highly uncertain and have large prediction errors. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide a method and device for predicting the depth of the overpressure top surface of an exploration well before drilling, so as to solve the problem of large uncertainty and large prediction error in the current prediction results of the overpressure top surface depth of an exploration well before drilling.

[0005] To achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention discloses a method for predicting the depth of the overpressure top surface before drilling an exploration well, comprising: Collect formation pressure test data of wells drilled in the study area, including multiple formation pressure test points of wells drilled; Obtain density curves for exploration wells; According to the density curve of the exploration well, the overburden pressure P of the exploration well is calculated respectively. O and the hydrostatic pressure P of the exploration well 静水 ; According to the overburden pressure P of the exploration well O , the hydrostatic pressure P of the exploration well 静水 and the pressure test points of the drilled formations to obtain the overpressure top depth H of the exploration well before drilling. TOP .

[0006] Wherein, obtaining the density curve of the exploration well comprises the following steps: Collect density data of wells drilled in the study area; According to the density data of the wells drilled in the study area, a trend curve of density variation with burial depth in the study area is established; Based on the trend curve of density variation with burial depth in the study area, the density curve of the exploration well is obtained.

[0007] Specifically, the overburden pressure P of the exploration well is O The calculation expression is: (Formula 1) In the formula, is the depth of the overlying rock layer; It is the density corresponding to the depth H of the overburden formation of the density curve of the exploration well.

[0008] Specifically, the hydrostatic pressure P of the exploration well 静水 The calculation expression is: (Formula 2) In the formula, is the depth of the overlying rock layer; It is the formation water density corresponding to the depth H of the overlying rock formation of the density curve of the exploration well.

[0009] Among them, the overpressure top depth H of the exploration well before drilling is obtained TOP The following steps are involved: The overburden pressure P of the exploration well O , the hydrostatic pressure P of the exploration well 静水 The multiple drilled formation pressure test points are plotted in the same depth and pressure coordinate system to obtain the overburden formation pressure P of the exploration well. O , Hydrostatic pressure P of the exploration well 静水 Interaction plots of depth and pressure for multiple drilled formation pressure test points; In the exploration well, the overburden pressure P O , Hydrostatic pressure P of the exploration well 静水 Draw an analysis auxiliary line P on the interactive diagram of depth and pressure of multiple drilled formation pressure test points L , the analysis auxiliary line P L The overburden pressure P parallel or approximately parallel to the exploration well O And it should pass through the dense area of ​​drilled formation pressure test points as much as possible; According to the analysis of auxiliary line P L and hydrostatic pressure P 静水 The depth of the intersection point is used to obtain the overpressure top depth H before drilling the exploration well. TOP .

[0010] Specifically, the analysis auxiliary line P L Depth on With pressure The relational expression is: (Formula 3) In the formula, The auxiliary line P for this analysis L Depth on; The auxiliary line P for this analysis L Depth on The pressure of is the slope; is the intercept.

[0011] Specifically, the analysis auxiliary line P L With the hydrostatic pressure P 静水 The depth of the intersection is the overpressure top depth H before drilling the exploration well. TOP .

[0012] In a second aspect, the present invention discloses a device for predicting the depth of the overpressure top surface before drilling an exploration well, comprising: The first unit is used to collect formation pressure test data of wells that have been drilled in the study area, including multiple formation pressure test points of wells that have been drilled; The second unit is used to obtain the density curve of the exploration well; The third unit is used to calculate the overburden pressure P of the exploration well according to the density curve of the exploration well. O and the hydrostatic pressure P of the exploration well 静水 ; The fourth unit is used to determine the overburden pressure P of the exploration well according to the overburden pressure P O , the hydrostatic pressure P of the exploration well 静水 and the pressure test points of the drilled formations to obtain the overpressure top depth H of the exploration well before drilling. TOP .

[0013] In a third aspect, the present invention discloses a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of the above method when executed by a processor.

[0014] In a fourth aspect, the present invention discloses a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above method when executing the computer program.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (I) The present invention discloses a method for predicting the depth of the overpressure top surface of an exploration well before drilling, comprising: collecting formation pressure test data of wells that have been drilled in a study area, including a plurality of formation pressure test points of the wells that have been drilled; obtaining a density curve of the exploration well; and calculating the overburden formation pressure P of the exploration well according to the density curve of the exploration well. O and the hydrostatic pressure P of the exploration well 静水According to the overburden pressure P of the exploration well O , the hydrostatic pressure P of the exploration well 静水 and the pressure test points of the drilled formations to obtain the overpressure top depth H of the exploration well before drilling. TOP The method for predicting the depth of the overpressure top surface before drilling an exploration well disclosed in the present invention uses the trend of density change with burial depth and the test data of formation pressure of the drilled well for analysis, avoiding the uncertainty caused by relying solely on formation velocity to predict the overpressure top surface, and improving the accuracy of the prediction of the overpressure top surface before drilling an exploration well.

[0016] (ii) The present invention discloses a method for predicting the depth of the overpressure top surface of an exploration well before drilling. The method is simple to operate and easy to implement. The steps of the method are clear and the calculation process is relatively simple, which is convenient for promotion and application in actual exploration work, thereby improving work efficiency and reducing drilling risks. As a new method, it can improve the accuracy of predicting the overpressure top surface of an exploration well before drilling. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the overburden pressure P of the exploration well provided in Example 1 of the present invention O , Hydrostatic pressure P of the exploration well 静水 Interaction plot of depth versus pressure for multiple drilled formation pressure test points. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is described clearly and completely. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] In order to solve the problem that the prediction results of the overpressure top depth before drilling an exploration well are currently large in uncertainty and large in prediction error, the present invention discloses a method for predicting the overpressure top depth before drilling an exploration well, comprising: collecting formation pressure test data of wells that have been drilled in a study area, including a plurality of formation pressure test points of wells that have been drilled; obtaining a density curve of the exploration well; and calculating the overburden formation pressure P of the exploration well according to the density curve of the exploration well. O and the hydrostatic pressure P of the exploration well 静水 According to the overburden pressure P of the exploration well O , the hydrostatic pressure P of the exploration well 静水 and the pressure test points of the drilled formations to obtain the overpressure top depth H of the exploration well before drilling. TOP The method for predicting the depth of the overpressure top surface of an exploration well before drilling disclosed in the present invention improves the accuracy and reliability of the prediction of the overpressure top surface of an exploration well before drilling, and provides a new method for predicting the depth of the overpressure top surface of an exploration well before drilling for the oil drilling field.

[0020] Example 1: A method for predicting the depth of the overpressure top surface before drilling an exploration well Embodiment 1 provides a method for predicting the depth of the overpressure top surface of an exploration well before drilling, comprising the following steps: Step a: Collect formation pressure test data of wells drilled in the study area, including multiple formation pressure test points of wells drilled; Step b: Obtaining the density curve of the exploration well, including the following steps: Step b1: Collect density data of wells drilled in the study area; Step b2: Establish a trend curve of density variation with burial depth in the study area based on the density data of the wells drilled in the study area; Step b3: Obtain the density curve of the exploration well based on the trend curve of density variation with burial depth in the study area.

[0021] Step c: Calculate the overburden pressure P of the exploration well according to the density curve of the exploration well. O and the hydrostatic pressure P of the exploration well 静水 ; Wherein, the overburden pressure P of the exploration well is O The calculation expression is: (Formula 1) In the formula, is the depth of the overlying rock layer; It is the density corresponding to the depth H of the overburden formation of the density curve of the exploration well.

[0022] The hydrostatic pressure P of the exploration well 静水 The calculation expression is: (Formula 2) In the formula, is the depth of the overlying rock layer; It is the formation water density corresponding to the depth H of the overlying rock formation of the density curve of the exploration well.

[0023] Specifically, In the implementation of a certain exploration well, 1g / cm 3 .

[0024] Step d: According to the overburden pressure P of the exploration well O , the hydrostatic pressure P of the exploration well 静水 and the pressure test points of the drilled formations to obtain the overpressure top depth H of the exploration well before drilling. TOP , including the following steps: Step d1: The overburden pressure P of the exploration well O, the hydrostatic pressure P of the exploration well 静水 The multiple drilled formation pressure test points are plotted in the same depth and pressure coordinate system to obtain the overburden formation pressure P of the exploration well. O , Hydrostatic pressure P of the exploration well 静水 Interaction plots of depth and pressure at multiple drilled formation pressure test points, such as Figure 1 shown.

[0025] Step d2: The overburden pressure P of the exploration well O , Hydrostatic pressure P of the exploration well 静水 Draw an analysis auxiliary line P on the interactive diagram of depth and pressure of multiple drilled formation pressure test points L , the analysis auxiliary line P L The overburden pressure P parallel or approximately parallel to the exploration well O And try to pass through dense areas of drilled formation pressure test points as much as possible.

[0026] Wherein, the analysis auxiliary line P L Depth on With pressure The relational expression is: (Formula 3) In the formula, The auxiliary line P for this analysis L Depth on; The auxiliary line P for this analysis L Depth on The pressure of is the slope; is the intercept.

[0027] Specifically, in the implementation of a certain exploration well, Take 40, Take 800.

[0028] Step d3: According to the analysis of auxiliary line P L and hydrostatic pressure P 静水 The depth of the intersection point is used to obtain the overpressure top depth H before drilling the exploration well. TOP .

[0029] Specifically, the analysis auxiliary line P L With the hydrostatic pressure P 静水 The depth of the intersection is the overpressure top depth H before drilling the exploration well. TOP .

[0030] Specifically, in the implementation of a certain exploration well, the overpressure top depth H before drilling the exploration well isTOP It is 1350m.

[0031] Example 2: A device for predicting the top surface of overpressure before drilling an exploration well Embodiment 2 provides a device for predicting the overpressure top surface of an exploration well before drilling, comprising: The first unit is used to collect formation pressure test data of wells that have been drilled in the study area, including multiple formation pressure test points of wells that have been drilled; The second unit is used to obtain the density curve of the exploration well; The third unit is used to calculate the overburden pressure P of the exploration well according to the density curve of the exploration well. O and the hydrostatic pressure P of the exploration well 静水 ; The fourth unit is used to determine the overburden pressure P of the exploration well according to the overburden pressure P O , the hydrostatic pressure P of the exploration well 静水 and the pressure test points of the drilled formations to obtain the overpressure top depth H of the exploration well before drilling. TOP .

[0032] Embodiment 3: A computer-readable storage medium Embodiment 3 provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the method of embodiment 1 are implemented.

[0033] Embodiment 4: A computer device Embodiment 4 provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method of embodiment 1 when executing the computer program.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for predicting the depth of the overpressure top surface of an exploration well before drilling, characterized in that: include Collect formation pressure test data of wells drilled in the study area, including multiple formation pressure test points of wells drilled; Obtain density curves for exploration wells; According to the density curve of the exploration well, the overburden pressure P of the exploration well is calculated respectively. O and the hydrostatic pressure P of the exploration well 静水 ; According to the overburden pressure P of the exploration well O , the hydrostatic pressure P of the exploration well 静水 and the pressure test points of the drilled formations to obtain the overpressure top depth H of the exploration well before drilling. TOP .

2. The method for predicting the depth of the overpressure top surface before drilling an exploration well according to claim 1, characterized in that: Obtaining the density curve of the exploration well comprises the following steps: Collect density data of wells drilled in the study area; According to the density data of the wells drilled in the study area, a trend curve of density variation with burial depth in the study area is established; Based on the trend curve of density variation with burial depth in the study area, the density curve of the exploration well is obtained.

3. The method for predicting the depth of the overpressure top surface before drilling an exploration well according to claim 1, characterized in that: The overburden pressure P of the exploration well O The calculation expression is: (Formula 1) In the formula, is the depth of the overlying rock layer; It is the density corresponding to the depth H of the overburden formation of the density curve of the exploration well.

4. The method for predicting the depth of the overpressure top surface before drilling an exploration well according to claim 1, characterized in that The hydrostatic pressure P of the exploration well 静水 The calculation expression is: (Formula 2) In the formula, is the depth of the overlying rock layer; It is the formation water density corresponding to the depth H of the overlying rock formation of the density curve of the exploration well.

5. The method for predicting the depth of the overpressure top surface before drilling an exploration well according to claim 1, characterized in that: The depth H of the overpressure top surface before drilling of the exploration well is obtained. TOP The following steps are involved: The overburden pressure P of the exploration well O , the hydrostatic pressure P of the exploration well 静水 The multiple drilled formation pressure test points are plotted in the same depth and pressure coordinate system to obtain the overburden formation pressure P of the exploration well. O , Hydrostatic pressure P of the exploration well 静水 Interaction plots of depth and pressure for multiple drilled formation pressure test points; In the exploration well, the overburden pressure P O , Hydrostatic pressure P of the exploration well 静水 Draw an analysis auxiliary line P on the interactive diagram of depth and pressure of multiple drilled formation pressure test points L , the analysis auxiliary line P L The overburden pressure P parallel or approximately parallel to the exploration well O And it should pass through the dense area of ​​drilled formation pressure test points as much as possible; According to the analysis of auxiliary line P L and hydrostatic pressure P 静水 The depth of the intersection point is used to obtain the overpressure top depth H before drilling the exploration well. TOP .

6. The method for predicting the depth of the overpressure top surface before drilling an exploration well according to claim 5, characterized in that: The analysis auxiliary line P L Depth on With pressure The relational expression is: (Formula 3) In the formula, The auxiliary line P for this analysis L Depth on; The auxiliary line P for this analysis L Depth on The pressure of is the slope; is the intercept.

7. The method for predicting the depth of the overpressure top surface before drilling an exploration well according to claim 5, characterized in that: The analysis auxiliary line P L With the hydrostatic pressure P 静水 The depth of the intersection is the depth of the overpressure top surface before drilling the exploration well H TOP .

8. A device for predicting the depth of the overpressure top surface before drilling an exploration well, characterized in that: include The first unit is used to collect formation pressure test data of wells that have been drilled in the study area, including multiple formation pressure test points of wells that have been drilled; The second unit is used to obtain the density curve of the exploration well; The third unit is used to calculate the overburden pressure P of the exploration well according to the density curve of the exploration well. O and the hydrostatic pressure P of the exploration well 静水 ; The fourth unit is used to determine the overburden pressure P of the exploration well according to the overburden pressure P O , the hydrostatic pressure P of the exploration well 静水 and the pressure test points of the drilled formations to obtain the overpressure top depth H of the exploration well before drilling. TOP .

9. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the computer program is executed by a processor, the steps of any one of the methods described in claims 1 to 7 are implemented.

10. A computer device, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any one of the methods of claims 1 to 7 when executing the computer program.

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