A method for quantitatively judging overpressure in shallow formations in deep sea areas using well logging curves

Abstract

The present application provides a method for quantitatively judging overpressure in shallow formations in deep-sea areas using well logging curves, comprising the following steps: measuring wet density and testing mineral composition of muddy sediment samples in non-overpressure development areas; establishing a calibrated density logging curve between wet density and density logging values ​​at corresponding burial depths, and calibrating density logging values ​​at various burial depths of the well according to the calibrated density logging curve to obtain calibrated wet density; obtaining calibrated porosity curves at various burial depths of the well according to a calculation formula between porosity, average skeleton density, and calibrated wet density; establishing a trend model between porosity and burial depth under hydrostatic conditions; and identifying and quantitatively predicting overpressure in shallow formations in deep-sea areas according to the trend model between porosity and burial depth. The prediction model of the present application has high recognition accuracy and can effectively identify the overpressure section and degree of overpressure in the entire well section, thus making up for the problem of sparse deep-sea drilling and insufficient measured pressure data.

Description

Technical Field

[0001] The present application belongs to the field of geological exploration technology, and more specifically, relates to a method for quantitatively judging overpressure of shallow strata in deep-sea areas by using well logging curves. Background Art

[0002] Predicting shallow overpressure in deepwater formations is crucial for seafloor construction and gas hydrate accumulation. Currently, by establishing a normal trend line (compaction model) for the relationship between relevant logging parameters of muddy formations (such as porosity, natural gamma ray, resistivity, and acoustic transit time) and burial depth (H) under hydrostatic pressure, and comparing the collected field data with the compaction model, it is possible to predict formation pressure at various depths. Deepwater surface pressure data is primarily accurately acquired during drilling using CPT (Cone Penetrometer Testing) or PCPT (Piezone Penetrometer Testing) tools. Furthermore, deep formation overpressure is typically determined using negative deviations in resistivity curves and positive deviations in acoustic transit time curves, supplemented by DST (Drill-Stem Testing) field data for verification. However, due to the high cost and high risk of deepwater drilling, the scarcity of wells, and the often limited availability of measured pressure data, traditional methods are unsuitable for predicting overpressure in shallow, unconsolidated formations in deepwater areas. Therefore, establishing a compaction model is crucial for identifying shallow overpressure. In addition, compared with consolidated formations, deep-sea sediments are very loose, and the logging parameters collected by logging equipment have large errors. Directly using logging parameters to predict formation overpressure will lead to inaccurate prediction results. Summary of the Invention

[0003] The purpose of this application is to provide a method for quantitatively judging overpressure in shallow formations in deep-sea areas using well logging curves, so as to solve the technical problems that the overpressure prediction methods in the prior art are not suitable for overpressure prediction in shallow unconsolidated formations in deep-sea areas and the prediction results are inaccurate.

[0004] To achieve the above objectives, the present application provides a method for quantitatively determining overpressure in shallow formations in deep-sea areas using well logging curves, comprising the following steps:

[0005] Drilling cores in non-overpressured areas are used to measure the wet density and conduct mineral composition tests on muddy sediment samples. The wet density ρ0 of the muddy sediment samples is calculated based on the wet density measurement results, and the average skeleton density ρ of the muddy sediment samples is calculated based on the mineral composition test results. 骨架 ;

[0006] Establishing a corrected density logging curve between the wet density ρ0 and the density logging value ρ1 at the corresponding burial depth, and correcting the density logging value ρ1 at each burial depth of the well according to the corrected density logging curve to obtain a corrected wet density ρ0;

[0007] According to the porosity φ and the average skeleton density ρ 骨架 , the corrected wet density ρ0 is calculated using the formula (1) to obtain the corrected porosity curve at each depth of the well; the calculation formula (1) is: ρ0 = ρ 骨架 *(1 - φ)+ρ 水 *φ (1);

[0008] Establish a trend model between porosity φ and burial depth Z under hydrostatic conditions;

[0009] The overpressure of shallow strata in deep sea areas is identified and quantitatively predicted based on the trend model between the porosity φ and the burial depth Z.

[0010] Furthermore, the establishment of the trend model between the porosity φ and the burial depth Z includes the following steps:

[0011] Use formula (2) to calculate the effective stress σ at different burial depths Z in the hydrostatic state ν ';

[0012] According to the effective stress σ ν The formula (3) between ' and the specific volume ν establishes the model formula (4) between porosity φ and burial depth Z; the formula (2), the formula (3), and the formula (4) are respectively:

[0013] σ ν '=(ρ skeleton - ρ water)*(1-φ)*g*Z / 1000 (2)

[0014] ν = ν0* (σ ν ') C , ν=1 / (1-φ) (3)

[0015] 1 / (1 - φ) = ν0*[(ρ 骨架 -ρ 水 )*(1 - φ)* g*Z / 1000] C (4),

[0016] Where ν0 and C are constants.

[0017] Furthermore, according to different burial depths Z, the trend model between the porosity φ and the burial depth Z is established by adopting segmented fitting to obtain at least two trend models between the porosity φ and the burial depth Z in at least two different burial depth Z ranges.

[0018] Furthermore, the trend model between porosity φ and burial depth Z is obtained by fitting the data points with a burial depth of less than 50 m: 1 / (1-φ)=1.25398*[(ρ 骨架-ρ 水 )*(1-φ)*Z / 100] -0.33774 The trend model 2 between porosity φ and burial depth Z is obtained by fitting the data points with a depth greater than 50 m: 1 / (1-φ)=2.05992*[(ρ 骨架 -ρ 水 )*(1-φ)*Z / 100] -0.08257 .

[0019] Furthermore, the identification of overpressure in shallow strata in deep-sea areas based on the trend model between the porosity φ and the burial depth Z includes the following steps: if the porosity φ value determined by drilling is higher than the porosity φ value calculated according to the trend model between the porosity φ and the burial depth Z, then overpressure is identified at that location.

[0020] Furthermore, the quantitative prediction includes the following steps:

[0021] Pore ​​pressure P 孔隙 is the overburden stress P 上覆 and effective stress σ ν The difference between the two can be calculated by formula (5) and formula (6). The overpressure value △P is the pore pressure P 孔隙 and hydrostatic pressure P 静 The difference can be calculated by formula (7);

[0022] The formula (5), the formula (6), and the formula (7) are respectively:

[0023] P 上覆 =[ρ 骨架 *(1-φ)+ρ 水 *φ]*g*Z+ρ 水 *g*h 水深 (5)

[0024] P 孔隙 =P 上覆 -(ν / ν0) 1 / C (6)

[0025] △P=P 孔隙 -P 静 , P 静 =ρ 水 *g*(Z+h 水深 ) (7).

[0026] Furthermore, the corrected density logging curve is:

[0027] ρ0=a*ρ1+b,

[0028] Where a and b are constants and the unit of density is g / cm 3 .

[0029] Furthermore, the wells drilled in the non-overpressure development zone are background parameter wells, and their logging curves change stably with the burial depth Z.

[0030] Furthermore, the calculation of the wet density ρ0 includes the following steps: drilling and coring to obtain samples at different burial depths Z, sealing the samples with paraffin, measuring the volume with a graduated cylinder, and calculating the wet density ρ0 of the samples using a volume method.

[0031] Furthermore, the mineral component test is to analyze the percentage of each mineral component using XRD.

[0032] Compared with the existing technology, this application has the following technical effects:

[0033] The present invention discloses a method for quantitatively judging overpressure in shallow strata in deep-sea areas using well logging curves. The method can identify the overpressure situation in unconsolidated strata on the deep-sea surface and quantitatively predict the magnitude of the overpressure. The method is simple and intuitive. The trend model between porosity φ and burial depth Z established has high prediction accuracy, and can accurately identify overpressure development intervals. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0035] Figure 1 A flow chart of a method for quantitatively determining overpressure in shallow formations in deep-sea areas using well logging curves provided in an embodiment of the present application;

[0036] Figure 2 A is a density correction result diagram of Well A provided in an embodiment of the present application (the scattered points on the left in 2A are density logging values, and the scattered points on the right are the corrected density); Figure 2 B is the porosity correction result diagram of Well A (the scattered points on the left in 2B are the porosity logging values, and the scattered points on the right are the porosity values ​​after correction);

[0037] Figure 3 A is a correlation diagram between specific volume and effective stress based on data fitting of Well A with a burial depth of less than 50 m provided in an embodiment of the present application. Figure 3 B is a correlation diagram between specific volume and effective stress based on data fitting of Well A with a burial depth greater than 50 m provided in an embodiment of the present application;

[0038] Figure 4 A is the resistivity logging curve provided in the embodiment of this application, Figure 4 B is the acoustic time difference logging curve provided in the embodiment of the present application, Figure 4 C is an intersection diagram of the compaction trend model and the porosity curve provided in the embodiment of the present application;

[0039] Figure 5 A is a porosity anomaly result diagram of Well B provided in the embodiment of this application; Figure 5 B is a porosity anomaly result diagram of Well C provided in an embodiment of the present application;

[0040] Figure 6 A is a diagram showing the overpressure prediction results of Well B provided in the embodiment of the present application; Figure 6 B is a diagram of the overpressure prediction results of Well C provided in an embodiment of the present application. DETAILED DESCRIPTION

[0041] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0042] In this application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0043] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "an", "the" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0044] The embodiment of the present application provides a method for quantitatively judging overpressure of shallow formations in deep sea areas by using well logging curves, and its flow chart is as follows: Figure 1 As shown, the following steps are included:

[0045] (1) Wet density and mineral composition testing of muddy sediment samples;

[0046] (2) Correction of density logs and porosity curves;

[0047] (3) Establish a porosity-depth trend model under hydrostatic conditions;

[0048] (4) Identify and predict overpressure based on the porosity-depth trend model.

[0049] In the above step (1), the wells drilled in the non-overpressure development zone are used as background parameter wells, and their acoustic wave, natural gamma, resistivity and other logging curves change steadily with depth.

[0050] Drilling core samples were taken at different burial depths Z. The samples were sealed with paraffin and the volume was measured with a graduated cylinder. The wet density ρ0 was calculated using the volume method (density to volume ratio). The percentage of sediment mineral components (mainly quartz, feldspar, calcite, dolomite, and clay minerals) was determined using an XRD analyzer. The average skeletal density ρ of the sediment was calculated based on the density of each mineral. 骨架 .

[0051] In the above step (2), since the wet density ρ0 of the unconsolidated sample is generally higher than the density logging value of the corresponding buried depth, the wet density ρ0 calculated in step (1) is established with the density logging value ρ1 of the corresponding buried depth as a linear function: ρ0 = a*ρ1+b, where a and b are constants and the density unit is g / cm 3 , and then the wet density at each burial depth can be corrected by the established functional relationship formula. At the same time, assuming that the pore brine density ρ 水 1.024 g / cm 3 , then the porosity φ can be calculated using the following formula (1), so that the wet density ρ0 can be converted into the porosity φ of the corresponding depth;

[0052] ρ0=ρ 骨架 *(1-φ)+ρ 水 *φ (1).

[0053] In the above step (3), the effective stress σ at different burial depths Z under static water state is obtained using formula (2): ν '; and the effective stress σ ν ' has a power function relationship with the specific volume ν (ν = 1 / (1-φ), φ is the porosity) as shown in formula (3) (Long et al., 2011; doi:10.1016 / j.epsl.2011.02.007). Based on the porosity φ determined by drilling and the effective stress σ at the corresponding depth ν 'The constants ν0 and C can be fitted, where σ ν The unit of ' is MPa. Based on this, the porosity φ-burial depth Z compaction trend model shown in formula (4) can be established;

[0054] σ ν '=(ρ skeleton - ρ water)*(1-φ)*g*Z / 1000 (2)

[0055] ν=ν0*(σ ν ') C (3)

[0056] 1 / (1-φ)=ν0*[(ρ 骨架 -ρ 水 )*(1-φ)*g*Z / 1000] C (4).

[0057] In the above step (4), formula (4) indicates the theoretical porosity value at a certain depth during normal compaction. When the porosity value of the local formation is higher than the theoretical value, it indicates the existence of overpressure. Combined with formula (3), the pore pressure P 孔隙 is the overburden stress P 上覆 and effective stress σ ν The difference between the two can be calculated by formulas (5) and (6), and the overpressure value △P is the pore pressure P 孔隙 and hydrostatic pressure P 静 The difference can be calculated by formula (7);

[0058] P 上覆 =[ρ 骨架 *(1-φ)+ρ 水 *φ]*g*Z+ρ 水 *g*h 水深 (5)

[0059] P 孔隙 =P 上覆 -(ν / ν0) 1 / C (6)

[0060] △P=P 孔隙 -P 静 , P 静 =ρ 水 *g*(Z+h 水深 ) (7).

[0061] This embodiment of the application uses wells A, B, and C in the deepwater area of ​​the Qiongdongnan Basin as research objects, and combines core samples and well logging curves to perform overpressure identification and prediction, including the following steps:

[0062] 1) Well A in the deepwater area of ​​the Qiongdongnan Basin is the background parameter well in this area. The seabed water depth is 1820m and the drilling depth is 260m. The formation drilled through does not develop overpressure. The core obtained from this well is the sediment compacted under hydrostatic state. Lithological samples at different depths were taken for wet density and mineral composition tests. The test method for the wet density (ρ0) of the sample is as follows: the initial sample is weighed (M0) and then immersed in liquid paraffin. After it is completely wrapped by the wax mold, it is taken out and weighed after cooling (M1); then the volume of the sample after wax sealing is measured by the water displacement method (V1). According to the density of paraffin wax (about 0.9g / cm 3) and the difference in mass before and after wax sealing to calculate the wax mold volume (V2). The sample volume (V0) is the difference between the sample volume after sealing (V1) and the wax mold volume (V2). Therefore, the wet density (ρ0) is the ratio of the mass before wax sealing (M0) to the sample volume (V0). Specific parameters are shown in Table 1. The mineral components and contents of the sediments tested by X-ray diffraction analyzer (XRD) are shown in Table 2. The sediment skeleton density ρ is calculated by combining the density of each single mineral. 骨架 (formation density assuming zero porosity), ρ 骨架 The average value is 2.72g / cm 3 .

[0063] Table 1 Sediment sample wet density test analysis table

[0064]

[0065] Table 2 Analysis of sediment mineral composition and stratigraphic skeleton density

[0066]

[0067] 2) By comparing the wet density (ρ0) of the seven samples with the logging density (ρ1) at the corresponding depth (Table 1), it was found that the logging density (ρ1) at the corresponding depth was generally smaller, and the wet density (ρ0) and the logging density (ρ1) had a linear correlation: ρ0 = 1.1038*ρ1–0.12958. Based on this, the logging density (ρ1) of the entire well section can be converted into a correction value (ρ0), as shown in the following example: Figure 2 As shown in A, it reflects the changing trend of the formation wet density of the entire well section. 水 =1.024g / cm 3 , ρ 骨架 =2.72g / cm 3 , then according to the above formula (1), that is: ρ0=ρ 骨架 *(1-φ)+ρ 水 *φ) calculate the porosity correction value (φ), such as Figure 2 As shown in B.

[0068] 3) Based on the porosity (φ1, φ2, φ3······ at different depths (Z1, Z2, Z3·····, with a logging sample interval of 0.1524m), according to formula (2), that is: σ ν '=(ρ skeleton - ρ water)*(1-φ)*g*Z / 1000) can be recursively calculated to obtain the effective stress (σ ν '1、σ ν '2, σ ν'3······), and the porosity at different depths (φ1, φ2, φ3······) is converted into specific volume (ν1, ν2, ν3······) using the formula ν=1 / (1-φ). The effective stress (σ ν '1、σ ν '2, σ ν '3······) and the specific volume (ν1, ν2, ν3······) using formula (3), that is: ν=ν0*(σ ν ') C The power function relationship shown in the figure is used to fit the parameters to obtain the values ​​of ν0 and C. The formula (4) is further used, that is, 1 / (1-φ)=ν0*[(ρ 骨架 -ρ 水 )*(1-φ)*g*Z / 1000] C Develop a compaction model applicable to the local area.

[0069] In order to remove the abnormal influence of porosity data near the seabed interface depth, this improved method uses segmented fitting to obtain two fitting results, namely, fitting result ① from data points with a burial depth of less than 50m and fitting result ② from data points with a burial depth of more than 50m. Figure 3 A, 3B). For strata with a burial depth of less than 50m, ν0 = 1.25398, C = -0.33774; for strata with a burial depth greater than 50m, ν0 = 2.05992, C = -0.08257. Therefore, under normal compaction conditions, the relationship between the porosity and depth of the sediments in this area satisfies the following segmented compaction model, namely:

[0070] Model 1 (Z<50m):

[0071] 1 / (1-φ)=1.25398*[(ρ 骨架 -ρ 水 )*(1-φ)*Z / 100] -0.33774 ,

[0072] Model 2 (Z>50m):

[0073] 1 / (1-φ)=2.05992*[(ρ 骨架 -ρ 水 )*(1-φ)*Z / 100] -0.08257 .

[0074] This segmented compaction model can describe the theoretical porosity variation trend of sediments in this area during compaction under hydrostatic conditions.

[0075] 4) From a qualitative perspective, overpressure formations generally have larger porosity, increased acoustic transit time, and decreased resistivity compared to surrounding rocks. For background parameter well A, the resistivity and acoustic transit time curves do not show any abnormal deviations ( Figure 4 A and 4B), and the analysis of Well A using the segmented compaction model revealed that the theoretical values ​​based on Model 1 and Model 2 were basically consistent with the porosity values ​​( Figure 4 C). Overall, the above indicates that Well A lacks shallow overpressure sections and can be used to represent the hydrostatic sediment compaction process in this region. However, for Wells B and C (seafloor depths of 1510 m and 1540 m, respectively), the measured porosity deviates from the theoretical values ​​of Models 1 and 2. Two weak overpressure sections are observed at depths of 11.4-58.9 m and 70.8-152.9 m in Well B, and three weak overpressure sections are observed at depths of 21-38.5 m, 40.4-49.4 m, and 62.6-134.2 m in Well C.

[0076] From a quantitative perspective, the compaction model can also be used to calculate the magnitude of overpressure. First, the pore pressure P 孔隙 is the overburden stress P 上覆 and effective stress σ ν ', combined with formula (3), that is: ν=ν0*(σ ν ') C Infer P 孔隙 =P 上覆 -(ν / ν0) 1 / C .

[0077] Among them, P 上覆 =[ρ 骨架 *(1-φ)+ρ 水 *φ]*g*Z+ρ 水 *g*h 水深 .

[0078] Secondly, the overpressure value (△P) is the pore pressure (P 孔隙 ) and hydrostatic pressure (P 静 ), that is, △P=P 孔隙 -ρ 水 *g*(Z+h 水深 ), the above formula can finally be converted to:

[0079] △P=(ρ 骨架 -ρ 水 )*(1- φ)*g*Z - (ν / ν0) 1 / C (8),

[0080] Among them, when Z<50m, ν0=1.25398, C=-0.33774; when Z>50m, ν0=2.05992, C=-0.08257.

[0081] Finally, the corrected porosity (φ) and the corresponding specific volume (ν) are substituted into the above formula (8) to calculate the overpressure at different burial depths of the formation, as follows: Figure 6 As shown in Figure 2, the average overpressure values ​​of the two overpressure sections in Well B are 0.128 MPa and 0.496 MPa respectively. Figure 6 A), the average overpressure values ​​of the three overpressure sections in Well C are 0.101 MPa, 0.182 MPa and 0.462 MPa respectively. Figure 6 B).

[0082] The above embodiments merely illustrate several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for quantitatively judging overpressure in shallow strata in deep sea areas using well logging curves, which is applicable to overpressure prediction in shallow unconsolidated strata in deep sea areas, and is characterized by: The following steps are involved: Drilling cores in non-overpressured areas are used to measure the wet density and conduct mineral composition tests on muddy sediment samples. The wet density ρ0 of the muddy sediment samples is calculated based on the wet density measurement results, and the average skeleton density ρ of the muddy sediment samples is calculated based on the mineral composition test results. 骨架 ; Establishing a corrected density logging curve between the wet density ρ0 and the density logging value ρ1 at the corresponding burial depth, and correcting the density logging value ρ1 at each burial depth of the well according to the corrected density logging curve to obtain a corrected wet density ρ0; According to the porosity With the average skeletal density ρ 骨架 , the calculation formula (1) between the corrected wet density ρ0, to obtain the corrected porosity curve at each depth of the drilling; the calculation formula (1) is: ρ0=ρ 骨架 (1 - ) + ρ 水 (1); Establishing porosity under hydrostatic conditions and the trend model between burial depth Z; According to the porosity The trend model between Z and burial depth Z is used to identify and quantitatively predict overpressure in shallow strata in deep sea areas; According to the porosity The trend model between the depth Z and the overpressure of shallow strata in deep sea areas includes the following steps: If the porosity determined by drilling is Values ​​higher than the porosity The porosity calculated by the trend model between the depth Z value, then it is recognized that there is overpressure; The porosity The establishment of the trend model between and burial depth Z includes the following steps: Formula (2) is used to calculate the effective stress σ at different burial depths Z in the hydrostatic state ν '; According to the effective stress σ ν The porosity is established by the formula (3) between ' and the specific volume ν and the model formula (4) between the burial depth Z; the formula (2), the formula (3), and the formula (4) are respectively: s ν ' = (p 骨架 - r 水 )*(1 - ) g Z / 1000(2) n = n0 (s ν ') C ,ν=1 / (1- )(3) 1 / (1 - ) = ν0 [(p 骨架 - r 水 ) (1 - ) g Z / 1000] C (4) Where ν0 and C are constants.

2. The method for quantitatively determining overpressure in shallow formations in deep sea areas using well logging curves according to claim 1, characterized in that: According to the different burial depths Z, the porosity The trend model between the depth Z and the burial depth Z is established by segmented fitting to obtain at least two porosities in at least two different burial depth Z ranges. and the trend model between burial depth Z.

3. The method for quantitatively determining overpressure in shallow formations in deep sea areas using well logging curves according to claim 2, wherein: The porosity is obtained by fitting the data points with a burial depth of less than 50m. The trend model between the depth Z is 1 / (1- )=1.25398 [(ρ 骨架 -ρ 水 ) (1- ) Z / 100] -0.33774 ; Porosity is obtained by fitting the data points with a depth greater than 50m The trend model 2 between the depth Z is 1 / (1- ) =2.05992 [(ρ 骨架 -ρ 水 ) (1- ) Z / 100] -0.08257 .

4. The method for quantitatively determining overpressure in shallow formations in deep sea areas using well logging curves according to claim 1, wherein: The quantitative prediction includes the following steps: Pore ​​pressure P 孔隙 is the overburden stress P 上覆 and effective stress σ ν The difference between the two can be calculated by formula (5) and formula (6). The overpressure value △P is the pore pressure P 孔隙 and hydrostatic pressure P 静 The difference can be calculated by formula (7); The formula (5), the formula (6), and the formula (7) are respectively: P 上覆 =[p 骨架 (1- )+r 水 ] g Z+r 水 g h 水深 (5) P 孔隙 =P 上覆 - (n / n0) 1 / C (6) △P = P 孔隙 -P 静 ,P 静= ρ 水 g (Z+h 水深 )(7)。 5. The method for quantitatively determining overpressure in shallow strata in deep sea areas using well logging curves according to claim 1, wherein: The corrected density logging curve is: ρ0=a p1+b, Where a and b are constants and the unit of density is g / cm 3 .

6. The method for quantitatively determining overpressure in shallow strata in deep sea areas using well logging curves according to claim 1, wherein: The wells drilled in the non-overpressure development zone are background parameter wells, and their logging curves change steadily with the burial depth Z.

7. The method for quantitatively determining overpressure in shallow strata in deep sea areas using well logging curves according to claim 1, wherein: The calculation of the wet density ρ0 includes the following steps: drilling and coring to obtain samples at different burial depths Z, sealing the samples with paraffin wax and measuring the volume with a graduated cylinder, and calculating the wet density ρ0 of the samples by a volume method.

8. The method for quantitatively determining overpressure in shallow strata in deep sea areas using well logging curves according to claim 1, wherein: The mineral component test is to analyze the percentage of each mineral component using XRD.

Images