Method and system for determining lower limit value of salt rock deposition thickness for hydrocarbon source rock rehydrocarbon generation

Abstract

The application discloses a method and system for determining a lower limit value of a salt rock deposition thickness of rehydrocarbon generation of a hydrocarbon source rock, and relates to the technical field of oil exploration.The method comprises the following steps: calculating a top surface temperature T1 of the hydrocarbon source rock before salt rock deposition based on a deposition thickness Z1 of a stratum above the hydrocarbon source rock before the salt rock deposition; calculating a top surface temperature T2 of the hydrocarbon source rock after the salt rock deposition based on the deposition thickness Z1 of the stratum above the hydrocarbon source rock before the salt rock deposition and a salt rock deposition thickness Z2; when T2 >= T1, the hydrocarbon source rock will generate hydrocarbon again based on the top surface temperature T1 of the hydrocarbon source rock before the salt rock deposition and the top surface temperature T2 of the hydrocarbon source rock after the salt rock deposition; and calculating the lower limit value Z3 of the salt rock deposition thickness when T2 = T1 > a hydrocarbon generation threshold temperature.The application can quantitatively characterize the thermal state of the hydrocarbon source rock under the salt rock by clearly studying the salt rock thickness, the thermal physical property parameters of the salt rock and the surface heat flow, and can clearly determine the maturity of the hydrocarbon source rock, thereby providing a basic basis for further studying the evolution of the hydrocarbon source rock under the salt rock and the oil and gas reservoir forming process.

Description

Technical Field

[0001] This invention relates to the field of petroleum exploration technology, and in particular to a method and system for determining the lower limit of the thickness of salt rock sediments in which hydrocarbons are regenerated from source rocks. Background Technology

[0002] Salt-bearing basins are widely developed, and the formation of oil and gas reservoirs within these basins is often related to gypsum-salt layers. Although gypsum-salt layers constitute a relatively small proportion of the sedimentary rock series in these basins, they possess excellent compactness, thus serving as important caprocks for many large and super-large oil and gas fields. They significantly influence and control the accumulation and preservation of oil and gas. Furthermore, gypsum-salt rocks exhibit plasticity, which can cause changes in the structural deformation patterns of the basin's stratigraphy, forming salt-related structures of different properties and types, thus becoming important structural traps and migration channels within the basin.

[0003] In addition, gypsum-salt rocks possess unique thermophysical properties, including high thermal conductivity and low heat generation rate. Experimental measurements show that the thermal conductivity of gypsum-salt rocks is as high as 6 W / (m K), which is 2 to 3 times that of ordinary sedimentary rocks, while the heat generation rate is as low as 0.01–0.23 μW / m. 3 The thermal properties of gypsum-salt rocks are 1 / 20 to 1 / 30 that of ordinary sedimentary rocks. The generation and preservation of oil and gas are closely related to the distribution and evolution of formation temperature. The strong difference in thermal properties between gypsum-salt rocks and surrounding strata inevitably leads to changes in the basin's thermal regime. Studying the thermal effects of gypsum-salt strata in marine basins is of great significance for revealing the basin's thermal characteristics and evaluating oil and gas resources.

[0004] Temperature is a key factor influencing the thermal evolution of organic matter and hydrocarbon generation. Tectonic movements leading to strata uplift and erosion, or the unique thermophysical properties of salt rocks, can cause changes in strata temperature, thus affecting the evolution of source rock maturity. In non-salt basins, when source rocks are in the hydrocarbon generation stage, tectonic movements cause strata uplift and erosion, lowering strata temperature and halting maturity growth, thus stopping hydrocarbon generation. Only after the strata subside again and the temperature reaches its previous peak does maturity resume to increase. However, in saline basins, due to the unique thermophysical properties of salt rocks, an increase in salt layer thickness initially causes a decrease in the temperature of the subsalt source rocks during the hydrocarbon generation stage, halting maturity growth and stopping hydrocarbon generation. When the salt rock thickness reaches a certain lower limit, the temperature of the subsalt source rocks rises again, exceeding the temperature of the previous hydrocarbon generation stage, maturity continues to increase, and hydrocarbon generation resumes.

[0005] In gypsum-salt basins, the temperature reduction of the underlying source rock organic matter depends on the salt content and thickness of the strata. The gypsum-salt layer has a relatively high thermal conductivity compared to the surrounding strata, forming a rapid heat flow channel. Similar to water flowing in the direction of least resistance, the low thermal resistance of the gypsum-salt layer causes rapid heat flow from its lower and surrounding areas to the salt layer, exhibiting an "endothermic" function. This leads to a rapid temperature reduction in the underlying strata, creating a "chimney effect" in the overlying layers, resulting in relatively lower temperatures in the subsalt strata and relatively higher temperatures in the overlying strata. However, as the salt rock thickness increases, when the temperature of the top surface of the subsalt source rock reaches or exceeds the temperature before salt deposition, the maturity of the subsalt source rock will increase again. Defining this lower limit allows for quantitative characterization of the thermal state of the subsalt source rock, clarifying the process of source rock maturity changes, and providing fundamental evidence for further research on the evolution of subsalt source rocks and hydrocarbon accumulation processes.

[0006] The above analysis of existing technologies shows that the cooling effect of salt rock deposition on subsalt source rocks is mainly studied using numerical simulation and basin simulation methods. Assuming a certain salt rock thickness, the study aims to clarify the influence of changes in the thermal conductivity of the gypsum-salt layer on the temperature anomalies of the strata above and below the salt rock, as well as the influence of the geometry of the gypsum-salt layer on the geothermal anomalies. Existing studies have only investigated the cooling effect of salt rock deposition on subsalt strata. However, as the thickness of salt rock deposition increases, the temperature of subsalt source rocks will continue to increase, and no relevant studies have calculated or studied this lower limit. Summary of the Invention

[0007] The purpose of this invention is to provide a method and system for determining the lower limit of the thickness of salt sedimentary rocks for regeneration of hydrocarbons in source rocks. By clarifying the thickness of salt rocks, their thermal properties, and surface heat flow in the study area, the thermal state of subsalt source rocks can be quantitatively characterized, and the maturity of the source rocks can be determined, providing a fundamental basis for further research on the evolution of subsalt source rocks and hydrocarbon accumulation processes. To achieve the above objective, this invention provides the following technical solution:

[0008] On one hand, the present invention provides a method for determining the lower limit of the thickness of salt rock sediments in hydrocarbon source rocks that generate hydrocarbons again, the method comprising the following steps:

[0009] Based on the depositional thickness Z1 of the overlying strata of the source rock before salt deposition, the temperature T1 of the top surface of the source rock before salt deposition was calculated.

[0010] Based on the depositional thickness Z1 of the overlying strata of the source rock before salt deposition and the depositional thickness Z2 of the salt rock, the temperature T2 of the top surface of the source rock after salt deposition is calculated.

[0011] Based on the temperature T1 of the source rock before salt deposition and the temperature T2 of the source rock after salt deposition, the lower limit value Z3 of the salt deposition thickness is calculated.

[0012] Furthermore, when T2 ≥ T1, the source rock will generate hydrocarbons again;

[0013] Let T2 = T1 > hydrocarbon generation threshold temperature, and calculate the lower limit value Z3 of salt rock deposition thickness.

[0014] Furthermore, the formula for calculating the temperature of the top surface of the source rock before salt deposition is as follows:

[0015] T1=T0+q1Z1 / k1-A1Z1 2 / (2k1),

[0016] In the formula, T1 is the temperature of the top surface of the source rock before salt deposition, in °C; T0 is the surface temperature, in °C; and q1 is the surface heat flow before salt deposition, in mW / m³. 2 Z1 represents the depositional thickness of the overlying strata of the source rocks before salt deposition, in meters (m); k1 represents the thermal conductivity of the overlying strata of the source rocks before salt deposition, in W / m·K; A1 represents the heat generation rate of the overlying strata of the source rocks before salt deposition, in μW / m². 3 .

[0017] Furthermore, the formula for calculating the temperature of the top surface of the source rock after salt rock deposition is as follows:

[0018] T2=T0+q2Z2 / k2-A2Z2 2 / (2k2)+q2'Z1 / k1-A1Z1 2 / (2k1),

[0019] In the formula, T2 is the temperature of the top surface of the source rock after salt deposition, in °C; T0 is the surface temperature, in °C; and q2 is the surface heat flow after salt deposition, in mW / m². 2 q2' represents the subsalt heat flow following salt rock deposition, in mW / m 2 Z1 represents the sedimentary thickness of the overlying strata of the source rocks before salt deposition, in meters (m); Z2 represents the sedimentary thickness of the salt rocks, in meters (m); k1 represents the thermal conductivity of the overlying strata of the source rocks before salt deposition, in W / m·K; k2 represents the thermal conductivity of the salt rocks, in W / m·K; A1 represents the heat generation rate of the overlying strata of the source rocks before salt deposition, in μW / m³. 3 A2 represents the heat generation rate of the salt rock, in μW / m³. 3 .

[0020] Furthermore, the formula for calculating the subsalt heat flow after salt rock deposition is as follows:

[0021] q2'=q2-A2Z2,

[0022] In the formula, q2' represents the subsalt heat flow after salt rock deposition, in mW / m 2 q2 represents the surface heat flow after salt rock deposition, in mW / m 2A2 represents the heat generation rate of salt rock, in μW / m³. 3 Z2 represents the thickness of the salt rock deposit, in meters.

[0023] Furthermore, the formula for calculating the lower limit of the salt rock deposition thickness is as follows:

[0024]

[0025] In the formula, Z3 is the lower limit of the salt rock deposition thickness in meters (m); q1 is the surface heat flow before salt rock deposition in mW / m. 2 q2 represents the surface heat flow after salt rock deposition, in mW / m 2 k1 represents the thermal conductivity of the overlying strata rocks before the salt source rock deposition, in W / m·K; k2 represents the thermal conductivity of the salt rock, in W / m·K; A1 represents the heat generation rate of the overlying strata rocks before the salt source rock deposition, in μW / m 3 A2 represents the heat generation rate of salt rock, in μW / m³. 3 Z1 represents the depositional thickness of the overlying strata of the source rocks before salt deposition, in meters.

[0026] Based on the above method, on the other hand, the present invention provides a system for determining the lower limit of the thickness of salt rock sediments for regeneration of hydrocarbon source rocks, the system comprising: a first calculation unit, a second calculation unit and a third calculation unit;

[0027] The first calculation unit is used to calculate the top surface temperature T1 of the source rock before salt deposition, based on the depositional thickness Z1 of the overlying strata of the source rock before salt deposition.

[0028] The second calculation unit is used to calculate the temperature T2 of the top surface of the source rock after salt deposition, based on the depositional thickness Z1 of the overlying strata of the source rock before salt deposition and the depositional thickness Z2 of the salt rock.

[0029] The third calculation unit is used to calculate the lower limit value Z3 of the salt rock deposition thickness based on the temperature T1 of the top surface of the source rock before the salt rock deposition and the temperature T2 of the top surface of the source rock after the salt rock deposition.

[0030] Furthermore, when T2 in the second calculation unit is greater than or equal to T1 in the first calculation unit, the source rock will generate hydrocarbons again;

[0031] Let T2 = T1 > hydrocarbon generation threshold temperature, and calculate the lower limit value Z3 of salt rock deposition thickness.

[0032] Furthermore, the formula for calculating T1 in the first calculation unit is:

[0033] T1=T0+q1Z1 / k1-A1Z1 2 / (2k1),

[0034] In the formula, T1 is the temperature of the top surface of the source rock before salt deposition, in °C; T0 is the surface temperature, in °C; and q1 is the surface heat flow before salt deposition, in mW / m³. 2 Z1 represents the depositional thickness of the overlying strata of the source rocks before salt deposition, in meters (m); k1 represents the thermal conductivity of the overlying strata of the source rocks before salt deposition, in W / m·K; A1 represents the heat generation rate of the overlying strata of the source rocks before salt deposition, in μW / m². 3 .

[0035] Furthermore, the formula for calculating T2 in the second calculation unit is:

[0036] T2=T0+q2Z2 / k2-A2Z2 2 / (2k2)+q2'Z1 / k1-A1Z1 2 / (2k1),

[0037] In the formula, T2 is the temperature of the top surface of the source rock after salt deposition, in °C; T0 is the surface temperature, in °C; and q2 is the surface heat flow after salt deposition, in mW / m². 2 q2' represents the subsalt heat flow following salt rock deposition, in mW / m 2 Z1 represents the sedimentary thickness of the overlying strata of the source rocks before salt deposition, in meters (m); Z2 represents the sedimentary thickness of the salt rocks, in meters (m); k1 represents the thermal conductivity of the overlying strata of the source rocks before salt deposition, in W / m·K; k2 represents the thermal conductivity of the salt rocks, in W / m·K; A1 represents the heat generation rate of the overlying strata of the source rocks before salt deposition, in μW / m³. 3 A2 represents the heat generation rate of the salt rock, in μW / m³. 3 .

[0038] Furthermore, the calculation formula for q2' in the second calculation unit is:

[0039] q2'=q2-A2Z2,

[0040] In the formula, q2' represents the subsalt heat flow after salt rock deposition, in mW / m 2 q2 represents the surface heat flow after salt rock deposition, in mW / m 2 A2 represents the heat generation rate of salt rock, in μW / m³. 3 Z2 represents the thickness of the salt rock deposit, in meters.

[0041] Furthermore, the calculation formula for Z3 in the third calculation unit is as follows:

[0042]

[0043] In the formula, Z3 is the lower limit of the salt rock deposition thickness in meters (m); q1 is the surface heat flow before salt rock deposition in mW / m.2 q2 represents the surface heat flow after salt rock deposition, in mW / m 2 k1 represents the thermal conductivity of the overlying strata rocks before the salt source rock deposition, in W / m·K; k2 represents the thermal conductivity of the salt rock, in W / m·K; A1 represents the heat generation rate of the overlying strata rocks before the salt source rock deposition, in μW / m 3 A2 represents the heat generation rate of salt rock, in μW / m³. 3 Z1 represents the depositional thickness of the overlying strata of the source rocks before salt deposition, in meters.

[0044] The technical effects and advantages of this invention are as follows:

[0045] First, by using the one-dimensional steady-state heat conduction equation, the temperature variation characteristics of the top surface of the subsalt source rock can be clearly defined by combining the thickness of the salt rock, the thermal properties of the salt rock and the subsalt strata, and the geothermal heat flow characteristics after the salt rock deposition.

[0046] Second, in sedimentary basins with thick salt deposits, we can quantitatively characterize the lower limit of the increase in temperature at the top surface of the subsalt source rock as the thickness of the salt deposits increases.

[0047] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0048] Figure 1 This is a flowchart of a method for determining the lower limit of the thickness of salt rock sediments in hydrocarbon source rocks for regeneration, according to the present invention.

[0049] Figure 2 This is a flowchart illustrating the technical process of determining the lower limit of salt layer deposition thickness for regeneration of hydrocarbon source rocks according to the present invention.

[0050] Figure 3 This is a schematic diagram showing the top temperature of the source rock at different depositional periods according to the present invention;

[0051] Figure 4 This is a graph showing the temperature variation at the top of the source rock over geological time according to the present invention.

[0052] Figure 5 This is a schematic diagram showing the temperature and maturity of the subsalt AA group source rocks in a certain basin.

[0053] Figure 6 This is a schematic diagram showing the oil generation from the subsalt AA group source rocks in a certain basin. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] To address the shortcomings of existing technologies, this invention discloses a method for determining the lower limit of the thickness of salt rock sediments in hydrocarbon source rocks that facilitate regeneration of hydrocarbons. Figure 1 This is a flowchart of a method for determining the lower limit of the thickness of salt rock sediments in hydrocarbon source rocks for regeneration, as described in this invention. Figure 1 As shown, the method includes the following steps:

[0056] Based on the depositional thickness Z1 of the overlying strata of the source rock before salt deposition, the temperature T1 of the top surface of the source rock before salt deposition was calculated.

[0057] Based on the depositional thickness Z1 of the overlying strata of the source rock before salt deposition and the depositional thickness Z2 of the salt rock, the temperature T2 of the top surface of the source rock after salt deposition is calculated.

[0058] Based on the temperature T1 of the source rock before salt deposition and the temperature T2 of the source rock after salt deposition, the lower limit value Z3 of the salt deposition thickness is calculated.

[0059] Preferably, when T2≥T1, the source rock will generate hydrocarbons again;

[0060] Let T2 = T1 > hydrocarbon generation threshold temperature, and calculate the lower limit value Z3 of salt rock deposition thickness.

[0061] This invention has been applied to a certain overseas offshore saline basin, such as... Figure 2 This is a flowchart illustrating the technical process of determining the lower limit of salt layer deposition thickness for hydrocarbon regeneration in source rocks according to the present invention. Figure 3 This is a schematic diagram showing the temperature at the top of the source rock during different depositional periods according to the present invention. Figure 3 a is a schematic diagram showing the temperature at the top of the source rock during the depositional period of the subsalt strata. Figure 3 b is a schematic diagram showing the temperature at the top of the source rock during the salt deposition period. (For example...) Figure 2 As shown, the specific calculation steps are as follows:

[0062] First step, such as Figure 3 As shown in a, the temperature T1 of the top surface of the source rock before salt deposition is calculated using a one-dimensional steady-state heat conduction equation based on the depositional thickness Z1 of the overlying strata of the source rock before salt deposition.

[0063] T1=T0+q1Z1 / k1-A1Z1 2 / (2k1),

[0064] In the formula, T1 is the temperature of the top surface of the source rock before salt deposition, in °C; T0 is the surface temperature, in °C; and q1 is the surface heat flow before salt deposition, in mW / m³. 2 Z1 represents the depositional thickness of the overlying strata of the source rocks before salt deposition, in meters (m); k1 represents the thermal conductivity of the overlying strata of the source rocks before salt deposition, in W / m·K; A1 represents the heat generation rate of the overlying strata of the source rocks before salt deposition, in μW / m². 3 .

[0065] The value here is:

[0066] T0 = ​​15℃; q1 = 78mW / m 2 ;Z1=3000m; k1=2.98W / m·K; A1=0.64μW / m 3 ;

[0067] The temperature of the top surface of the source rock before salt deposition was calculated:

[0068] T1 = 92.6℃.

[0069] The second step, as Figure 3 As shown in b, based on the sedimentary thickness Z1 of the overlying strata of the source rock before salt deposition and the sedimentary thickness Z2 of the overlying strata of the source rock after salt deposition, the temperature T2 of the top surface of the source rock after salt deposition is calculated using a one-dimensional steady-state heat conduction equation.

[0070] T2=T0+q2Z2 / k2-A2Z2 2 / (2k2)+q2'Z1 / k1-A1Z1 2 / (2k1),

[0071] q2'=q2-A2Z2,

[0072] In the formula, T2 is the temperature of the top surface of the source rock after salt deposition, in °C; T0 is the surface temperature, in °C; and q2 is the surface heat flow after salt deposition, in mW / m². 2 q2' represents the subsalt heat flow following salt rock deposition, in mW / m 2 Z1 represents the sedimentary thickness of the overlying strata of the source rocks before salt deposition, in meters (m); Z2 represents the sedimentary thickness of the salt rocks, in meters (m); k1 represents the thermal conductivity of the overlying strata of the source rocks before salt deposition, in W / m·K; k2 represents the thermal conductivity of the salt rocks, in W / m·K; A1 represents the heat generation rate of the overlying strata of the source rocks before salt deposition, in μW / m³. 3 A2 represents the heat generation rate of the salt rock, in μW / m³. 3 .

[0073] The value here is:

[0074] T0=15℃; Z1=3000m; k1=2.98W / m·K; A1=0.64μW / m 3 q2=76mW / m 2 Z2 = 145.5m;

[0075] k2=5.40W / m·K; A2=0.22μW / m 3 .

[0076] The temperature of the top surface of the source rock after salt deposition was calculated:

[0077] T 2＝ 92.6℃.

[0078] like Figure 4 This is a graph showing the temperature change at the top of the source rock as the thickness of the salt rock deposition increases. Figure 4 This is a graph showing the temperature variation at the top of the source rock over geological time. Specifically, Figure 4 To illustrate the calculations using the one-dimensional steady-state heat conduction equation, basin simulation technology was employed to simulate the temperature at the top of the subsalt source rock. As the thickness of the salt deposit increases, the temperature at the top of the source rock initially decreases and then increases. Assuming the overlying strata thickness before salt deposition is 3000 m and the salt deposition time is 120–0 Ma, the results show that the temperature at the top of the source rock begins to decrease after salt deposition begins, but increases again after 55 Ma. When the salt deposition time is 0 Ma, the salt deposition thickness is 145.5 m.

[0079] The third step is to calculate the lower limit value Z3 of the salt rock deposition thickness based on the temperature T1 of the top surface of the source rock before salt rock deposition and the temperature T2 of the top surface of the source rock after salt rock deposition.

[0080] The deposition of salt rock leads to a decrease in the temperature of the subsalt strata. However, as the salt rock reaches a certain thickness, when T2 ≥ T1, the source rock will generate hydrocarbons again.

[0081] Let T2 = T1 > hydrocarbon generation threshold temperature;

[0082]

[0083] The value here is:

[0084] q1=78mW / m 2 ;Z1=3000m; k1=2.98W / m·K; A1=0.64μW / m 3 q2=76mW / m 2 ;

[0085] k2=5.40W / m·K; A2=0.22μW / m 3 ;

[0086] The lower limit of the salt rock deposition thickness was calculated:

[0087] Z3 = 145.5m.

[0088] On the other hand, the present invention also discloses a system for determining the lower limit of the thickness of salt rock sediments for regeneration of hydrocarbon source rocks, the system comprising: a first calculation unit, a second calculation unit and a third calculation unit;

[0089] The first calculation unit is used to calculate the top surface temperature T1 of the source rock before salt deposition, based on the depositional thickness Z1 of the overlying strata of the source rock before salt deposition.

[0090] The second calculation unit is used to calculate the temperature T2 of the top surface of the source rock after salt deposition, based on the depositional thickness Z1 of the overlying strata of the source rock before salt deposition and the depositional thickness Z2 of the salt rock.

[0091] The third calculation unit is used to calculate the lower limit value Z3 of the salt rock deposition thickness based on the temperature T1 of the top surface of the source rock before the salt rock deposition and the temperature T2 of the top surface of the source rock after the salt rock deposition.

[0092] Furthermore, when T2 in the second calculation unit is greater than or equal to T1 in the first calculation unit, the source rock will generate hydrocarbons again;

[0093] Let T2 = T1 > hydrocarbon generation threshold temperature, and calculate the lower limit value Z3 of salt rock deposition thickness.

[0094] This invention utilizes the differences in thermal conductivity and heat generation rate between salt rock and subsalt strata to calculate the lower limit of the salt rock depositional thickness required for re-hydrogenation in subsalt source rocks. This provides a fundamental basis for further research on the maturity and hydrocarbon generation history of subsalt source rocks. Figure 5 This is a schematic diagram showing the temperature and maturity of the subsalt AA group source rocks in a certain basin, as shown below. Figure 6 This is a schematic diagram illustrating the hydrocarbon generation of the subsalt AA Formation source rocks in a certain basin. From... Figure 5 and Figure 6 Studies of the AA Formation in a certain basin show that a thick set of salt rocks was deposited during the deposition of the Ariri Formation. As the salt rocks were deposited, the temperature decreased, the maturity stopped increasing, and hydrocarbon generation ceased. When the salt rocks reached a certain thickness, the temperature increased again, the maturity increased, and hydrocarbon generation continued.

[0095] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of determining a lower thickness limit value of salt rock deposits for the rehydrocarbon generation of a hydrocarbon source rock, characterized in that, The method includes the following steps: Based on the thickness of the overlying strata of the source rock before the salt rock deposition Z 1, calculating the temperature of the top surface of the source rock before the salt rock deposition T 1; Based on the sedimentary thickness of the overlying strata of the source rocks before salt deposition Z 1 and the thickness of salt rock sediments Z 2. Calculate the temperature of the top surface of the source rock after salt deposition. T 2; Based on the temperature of the top surface of the source rock before the salt rock deposition T 1 and the temperature of the top surface of the source rock after the salt rock deposition T 2. Calculate the lower limit of salt rock deposition thickness. Z 3; The formula for calculating the temperature of the top surface of the source rock before salt deposition is as follows: T 1 = T 0 +q 1 Z 1 / k 1 -A 1 Z 1 2 / (2k 1 ) ， In the formula, T 1 represents the temperature of the top surface of the source rock before salt deposition, in °C; T 0 represents the Earth's surface temperature, measured in °C. q 1 represents the surface heat flow before salt rock deposition, in mW / m 2 ; Z 1 represents the sedimentary thickness of the overlying strata of the source rocks before salt deposition, in meters; k 1 represents the thermal conductivity of the rocks in the strata overlying the source rocks before salt deposition, in W / m·K. A 1 represents the heat generation rate of the overlying strata rocks of the source rocks before salt deposition, in μW / m³. 3 The formula for calculating the temperature of the top surface of the source rock after salt rock deposition is as follows: T 2 = T 0 +q 2 Z 2 / k 2 -A 2 Z 2 2 / (2k 2 )+q 2 ’Z 1 / k 1 -A 1 Z 1 2 / (2k 1 ) ， In the formula, T 2 represents the temperature of the top surface of the source rock after salt deposition, in °C; T 0 represents the Earth's surface temperature, measured in °C. q 2 represents the surface heat flow after salt rock deposition, in mW / m 2 ; q 2 ’ This refers to the subsalt heat flow following salt rock deposition, expressed in mW / m. 2 ; Z 1 represents the sedimentary thickness of the overlying strata of the source rocks before salt deposition, in meters; Z 2 represents the thickness of the salt rock deposit, in meters (m). k 1 represents the thermal conductivity of the rocks in the strata overlying the source rocks before salt deposition, in W / m·K. k 2 represents the thermal conductivity of the salt rock, in W / m·K. A 1 represents the heat generation rate of the overlying strata rocks of the source rocks before salt deposition, in μW / m³. 3 , A 2 represents the heat generation rate of the salt rock, in μW / m³. 3 ; The formula for calculating the lower limit of the salt rock deposition thickness is as follows: Z 3 = ， In the formula, Z 3 represents the lower limit of salt rock deposition thickness, in meters (m). q 1 represents the surface heat flow before salt rock deposition, in mW / m 2 ; q 2 represents the surface heat flow after salt rock deposition, in mW / m 2 ; k 1 represents the thermal conductivity of the rocks in the strata overlying the source rocks before sedimentation, in W / m·K. k 2 represents the thermal conductivity of the salt rock, in W / m·K. A 1 represents the heat generation rate of the overlying strata rocks of the source rocks before salt deposition, in μW / m³. 3 ; A 2 represents the heat generation rate of the salt rock, in μW / m³. 3 ; Z 1 represents the depositional thickness of the overlying strata of the source rocks before the salt rock deposition, in meters.

2. The method for determining the lower limit of the thickness of salt rock sedimentary deposits for regeneration of hydrocarbon source rocks according to claim 1, characterized in that, when T 2≥ T At 1 hour, the source rock will generate hydrocarbons again; make T 2= T 1> Hydrocarbon generation threshold temperature, calculating the lower limit of salt rock deposition thickness Z 3.

3. The method for determining the lower limit of the thickness of salt rock sedimentary deposits for regeneration of hydrocarbon source rocks according to claim 1, characterized in that, The formula for calculating the subsalt heat flow after salt rock deposition is as follows: q 2 ’ = q 2 -A 2 Z 2， In the formula, q 2' represents the subsalt heat flow after salt rock deposition, in mW / m 2 ; q 2 represents the surface heat flow after salt rock deposition, in mW / m 2 ; A 2 represents the heat generation rate of the salt rock, in μW / m³. 3 ; Z 2 represents the thickness of the salt rock deposit, in meters.

4. A system for determining the lower limit of the thickness of salt rock sedimentary deposits in hydrocarbon source rocks for regeneration, characterized in that, The system includes: a first computing unit, a second computing unit, and a third computing unit; The first calculation unit is used to calculate the depositional thickness of the overlying strata of the source rocks before salt rock deposition. Z 1. Calculate the temperature of the top surface of the source rock before salt deposition. T 1; The second calculation unit is used to calculate the depositional thickness of the overlying strata of the source rocks before salt deposition. Z 1 and the thickness of salt rock sediments Z 2. Calculate the temperature of the top surface of the source rock after salt deposition. T 2; The third calculation unit is used to calculate based on the temperature of the top surface of the source rock before the salt rock deposition. T 1 and the temperature of the top surface of the source rock after the salt rock deposition T 2. Calculate the lower limit of salt rock deposition thickness. Z 3; In the first computing unit T The formula for calculating 1 is: T 1 = T 0 +q 1 Z 1 / k 1 -A 1 Z 1 2 / (2k 1 ) ， In the formula, T 1 represents the temperature of the top surface of the source rock before salt deposition, in °C; T 0 represents the Earth's surface temperature, measured in °C. q 1 represents the surface heat flow before salt rock deposition, in mW / m 2 ; Z 1 represents the sedimentary thickness of the overlying strata of the source rocks before salt deposition, in meters; k 1 represents the thermal conductivity of the rocks in the strata overlying the source rocks before salt deposition, in W / m·K. A 1 represents the heat generation rate of the overlying strata rocks of the source rocks before salt deposition, in μW / m³. 3 ; In the second computing unit T The formula for calculating 2 is: T 2 = T 0 +q 2 Z 2 / k 2 -A 2 Z 2 2 / (2k 2 )+q 2 ’Z 1 / k 1 -A 1 Z 1 2 / (2k 1 ) ， In the formula, T 2 represents the temperature of the top surface of the source rock after salt deposition, in °C; T 0 represents the Earth's surface temperature, measured in °C. q 2 represents the surface heat flow after salt rock deposition, in mW / m 2 ; q 2 ’ This refers to the subsalt heat flow following salt rock deposition, expressed in mW / m. 2 ; Z 1 represents the sedimentary thickness of the overlying strata of the source rocks before salt deposition, in meters; Z 2 represents the thickness of the salt rock deposit, in meters (m). k 1 represents the thermal conductivity of the rocks in the strata overlying the source rocks before salt deposition, in W / m·K. k 2 represents the thermal conductivity of the salt rock, in W / m·K. A 1 represents the heat generation rate of the overlying strata rocks of the source rocks before salt deposition, in μW / m³. 3 , A 2 represents the heat generation rate of the salt rock, in μW / m³. 3 ; In the third computing unit Z The formula for calculating 3 is: Z 3 = ， In the formula, Z 3 represents the lower limit of salt rock deposition thickness, in meters (m). q 1 represents the surface heat flow before salt rock deposition, in mW / m 2 ; q 2 represents the surface heat flow after salt rock deposition, in mW / m 2 ; k 1 represents the thermal conductivity of the rocks in the strata overlying the source rocks before sedimentation, in W / m·K. k 2 represents the thermal conductivity of the salt rock, in W / m·K. A 1 represents the heat generation rate of the overlying strata rocks of the source rocks before salt deposition, in μW / m³. 3 ; A 2 represents the heat generation rate of the salt rock, in μW / m³. 3 ; Z 1 represents the depositional thickness of the overlying strata of the source rocks before the salt rock deposition, in meters.

5. The system for determining the lower limit of the thickness of salt rock sedimentary deposits for regeneration of hydrocarbon source rocks according to claim 4, characterized in that, When the second calculation unit T 2≥In the first calculation unit T At 1 hour, the source rock will generate hydrocarbons again; make T 2= T 1> Hydrocarbon generation threshold temperature, calculating the lower limit of salt rock deposition thickness Z 3.

6. The system for determining the lower limit of the thickness of salt rock sedimentary deposits for regeneration of hydrocarbon source rocks according to claim 4, characterized in that, In the second computing unit q 2 ’ The calculation formula is: q 2 ’ = q 2 -A 2 Z 2， In the formula, q 2' represents the subsalt heat flow after salt rock deposition, in mW / m 2 ; q 2 represents the surface heat flow after salt rock deposition, in mW / m 2 ; A 2 represents the heat generation rate of the salt rock, in μW / m³. 3 ; Z 2 represents the thickness of the salt rock deposit, in meters.

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