A method for judging the control of operation and storage of a sand cap element combination

Abstract

The application discloses a method for judging control migration and control accumulation by fault-sand-cap element combination, and relates to the technical field of oil and gas geological exploration. The method comprises the following steps. An oil and gas layer is selected, and the oil and gas layer is determined as a normal pressure-weak overpressure system; a fault in the oil and gas layer is identified, and a fault-sand-cap element of the fault is tested, wherein the fault-sand-cap element is fault throw, sand body thickness and non-permeable mudstone thickness; then, according to the fault-sand-cap element, a ratio of the fault throw to the sand body thickness is calculated to be greater than 1 or less than 1, and a ratio of the fault throw to the non-permeable mudstone thickness is calculated to be greater than 1 or less than 1; whether oil and gas migration and / or accumulation occurs in the oil and gas layer is determined according to the calculated ratio of the fault throw to the sand body thickness and the ratio of the fault throw to the non-permeable mudstone thickness. The method adopts fault-sand ratio and fault-mud ratio to comprehensively represent the control migration and control accumulation mechanism of the fault-sand-cap element combination under the normal pressure-weak overpressure system.

Description

Technical Field

[0001] This invention relates to the field of oil and gas geological exploration technology, specifically to a method for determining the control of migration and reservoir by combining fault-sand-caprock elements. Background Technology

[0002] Oil and gas migration and accumulation are key and core aspects of petroleum geology, but also weak links in oil and gas enrichment and target prediction research. Faults, sand bodies, and caprocks constrain the discovery of oil and gas migration and accumulation. The relationships between fault-sand, fault-caprock, and sand-caprock configurations have provided preliminary insights into oil and gas migration and accumulation mechanisms. Among these, the SSF (smearing factor) is used to constrain the possibility of continuous smearing in fault core shale, simulating the profile of abrasion-type smearing, and approximated as the ratio of fault displacement to caprock, which can be used to evaluate the vertical sealing capacity of faults. Many scholars have discussed the lateral transport capacity of fault-sand configurations from the perspective of different fault types and sand-caprock ratios. However, the comprehensive control mechanism of migration and accumulation under the coupling of fault-sand-caprock elements has not yet been thoroughly explored. Existing fault-sand, fault-caprock, and sand-caprock configurations are no longer sufficient to meet current exploration needs. For oil and gas migration and accumulation under normal to weakly overpressure systems, it is urgent to propose evaluation methods for the control of migration and accumulation under the combination of fault-sand-caprock elements. Summary of the Invention

[0003] The purpose of this invention is to provide a method for determining the control of migration and storage by combining fault-sand-capital elements. This method not only classifies faults, but also considers the different combinations of the control of migration and storage by multiple elements of fault-sand and fault-capital.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for determining transport and storage control based on the combination of fault-sand-capital elements includes the following steps:

[0006] Select an oil and gas reservoir and determine that the reservoir is an atmospheric-weak overpressure system;

[0007] Identify faults in oil and gas reservoirs and test the fault-sand-cap elements of the faults, wherein the fault-sand-cap elements are fault displacement, sand body thickness and non-permeable mudstone body thickness.

[0008] Subsequently, based on the aforementioned fault-sand-cap elements, the ratio of fault displacement to sand body thickness (fault-sand ratio, Hf / Hs) was calculated to be greater than 1 or less than 1, and the ratio of fault displacement to non-permeable mudstone body thickness (fault-mud ratio, Hf / Hm) was calculated to be greater than 1 or less than 1.

[0009] The migration and / or accumulation of oil and gas in the reservoir are determined by calculating the ratio of fault displacement to sand body thickness and the ratio of fault displacement to non-permeable mudstone body thickness.

[0010] Preferably, the fault is a parallel fault or a reverse fault.

[0011] More preferably, when the fault is a parallel fault, the fault-sand-cap element is the fault displacement, the thickness of a single sand body, and the thickness of the non-permeable mudstone body below the single sand body.

[0012] More preferably, the ratio of the fault displacement to the sand body thickness is >1, and the ratio of the fault displacement to the thickness of the impermeable mudstone body is <1, which indicates a complete sand-mudstone connection, which is conducive to hydrocarbon accumulation.

[0013] Alternatively, if the ratio of the fault displacement to the sand body thickness is greater than 1, and the ratio of the fault displacement to the thickness of the non-permeable mudstone body is greater than 1, it indicates partial sand-mud contact, which is conducive to oil and gas migration and reservoir formation.

[0014] More preferably, the ratio of the fault displacement to the sand body thickness is <1, and the ratio of the fault displacement to the thickness of the non-permeable mudstone body is <1, which indicates a sand-sand connection type, which is conducive to oil and gas migration and conduction, but not conducive to oil and gas accumulation.

[0015] Alternatively, if the ratio of the fault displacement to the sand body thickness is <1, and the ratio of the fault displacement to the thickness of the non-permeable mudstone body is >1, it indicates a sand-sand multi-connection type, which is conducive to the migration and conduction of oil and gas, but not conducive to the accumulation and formation of oil and gas reservoirs.

[0016] More preferably, when the fault is a reverse fault, the fault-sand-cap element is the fault displacement, the thickness of a single sand body in the oil and gas reservoir, and the thickness of the non-permeable mudstone body above the single sand body.

[0017] More preferably, the ratio of the fault displacement to the thickness of the impermeable mudstone body is <1, and the ratio of the fault displacement to the thickness of the sand body is >1, which indicates a complete sand-mud connection, which is conducive to hydrocarbon accumulation.

[0018] Alternatively, if the ratio of the fault displacement to the thickness of the impermeable mudstone body is <1, and the ratio of the fault displacement to the thickness of the sand body is <1, it indicates partial sand-mud contact, which is conducive to oil and gas migration and reservoir formation.

[0019] More preferably, the ratio of the fault displacement to the thickness of the impermeable mudstone body is greater than 1, and the ratio of the fault displacement to the thickness of the sand body is greater than 1, which indicates a sand-sand connection type, which is conducive to oil and gas migration and conduction, but not conducive to oil and gas accumulation.

[0020] Alternatively, if the ratio of the fault displacement to the thickness of the non-permeable mudstone body is greater than 1, and the ratio of the fault displacement to the thickness of the sand body is less than 1, it exhibits a sand-sand multi-connection type, which is conducive to the migration and conduction of oil and gas, but not conducive to the accumulation and formation of oil and gas reservoirs.

[0021] Preferably, the atmospheric pressure-weak overpressure system has a pressure coefficient between 0.9 and 1.2, wherein the pressure coefficient is the ratio of pore fluid pressure to hydrostatic pressure.

[0022] Compared with the prior art, the advantages of this invention are as follows:

[0023] This invention provides a method for controlling hydrocarbon migration and accumulation through the combination of fault-sand-caprock elements in an atmospheric-weak overpressure system, where the main controlling factors are hydrodynamics and the transport system. Under atmospheric-weak overpressure, the combination of fault-sand-caprock elements becomes the primary factor controlling hydrocarbon migration and accumulation. This technical solution not only classifies faults but also considers the different combinations of multiple fault-sand and fault-caprock elements in controlling migration and accumulation. Faults are divided into perpendicular faults (faults dipping in the same direction as the strata) and reverse faults (faults dipping in the opposite direction to the strata). The difference lies in the combination of perpendicular faults (parallel faults) and mudstone in the lower sand body controlling migration and accumulation, and the combination of reverse faults (reverse faults) and mudstone in the upper sand body controlling migration and accumulation. The fault-sand ratio (fault displacement / single sand body thickness) and the fault-mud ratio (fault displacement / single mudstone thickness) are used to characterize the mechanism of controlling migration and accumulation through the combination of fault-sand-caprock elements under atmospheric-weak overpressure.

[0024] The main characteristics of fault-controlled migration and reservoir formation are: fault-sand ratio > 1 (Hf / Hs > 1); when fault-mud ratio < 1 (Hf / Hm < 1), it is characterized by full sand-mud contact, which is conducive to hydrocarbon accumulation; when fault-mud ratio > 1 (Hf / Hm > 1), it is characterized by partial sand-mud contact, which is conducive to hydrocarbon migration and accumulation; Hf / Hs < 1 and Hf / Hm < 1 are sand-sand top contact types, which are conducive to hydrocarbon migration and conduction but not conducive to hydrocarbon accumulation; Hf / Hs < 1 and Hf / Hm > 1 are sand-sand multi-contact types, which are conducive to hydrocarbon migration and conduction but not conducive to hydrocarbon accumulation.

[0025] Reverse fault-controlled migration and reservoir formation is mainly characterized by a fault-mud ratio <1 (Hf / Hm <1). When the fault-sand ratio >1 (Hf / Hs >1), it is characterized by full sand-mud contact, which is conducive to hydrocarbon accumulation. When the fault-sand ratio <1 (Hf / Hs <1), it is characterized by partial sand-mud contact, which is conducive to hydrocarbon migration and accumulation. The Hf / Hs >1 and Hf / Hm >1 types are sand-sand top contact types, which are conducive to hydrocarbon migration and conduction but not conducive to hydrocarbon accumulation. The Hf / Hs <1 and Hf / Hm >1 types are sand-sand multi-contact types, which are conducive to hydrocarbon migration and conduction but not conducive to hydrocarbon accumulation. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a method for judging the combination of fault-sand-capsule elements to control transport and storage under normal pressure-weak overpressure system, provided by an embodiment of the present invention. Detailed Implementation

[0027] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. However, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0028] The main controlling factors for hydrocarbon migration and accumulation provided by this invention are hydrodynamics and the transport system. Under normal to weakly overpressure systems, the combination of fault-sand-caprock elements becomes the main factor controlling hydrocarbon migration and accumulation. This technical solution not only classifies faults but also considers the different combinations of fault-sandrock and fault-caprock elements that control migration and accumulation. Faults are divided into perpendicular faults (faults dip in the same direction as the strata) and reverse faults (faults dip in the opposite direction to the strata). The difference is that perpendicular faults (parallel faults) combined with the mudstone in the lower sand body control migration and accumulation, while reverse faults (reverse faults) combined with the mudstone in the upper sand body control migration and accumulation. Figure 1 The fault-sand-capital combination mechanism controlling migration and reservoir accumulation under normal-pressure to weakly overpressured systems is characterized by the fault-sand-capital combination of elements (fault displacement / single sand body thickness) and fault-mudstone ratio (fault displacement / single mudstone thickness).

[0029] This invention primarily reveals the mechanism of migration and reservoir control through the combination of fault-sand-caprock elements in exploited oil and gas fields, following the steps outlined in this invention.

[0030] First, determine whether the oil and gas reservoir is an atmospheric-to-weakly overpressure system (pressure coefficient < 1.2).

[0031] If not, this method is not applicable to systems with strong overpressure;

[0032] If so, the nature of the fault, whether it is a parallel fault or a reverse fault, can be determined by the fault dip and the stratigraphic dip.

[0033] If it is a parallel fault, calculate the fault displacement, the thickness of a single sand body in the oil and gas reservoir, and the thickness of the non-permeable rock mass (mudstone) below the single sand body.

[0034] If it is a reverse fault, calculate the fault displacement, the thickness of a single sand body in the oil and gas reservoir, and the thickness of the non-permeable rock mass (mudstone) above the single sand body.

[0035] Calculate the sand ratio and mud ratio;

[0036] Using logging, well logging, oil and gas testing, and geological analysis data, we can determine the migration and / or accumulation of oil and gas in oil and gas reservoirs;

[0037] If the oil and gas in the reservoir shows signs such as gas saturation <30%, fluorescence, oil traces, oil spots, or oil immersion, it is considered that oil and gas migration has occurred.

[0038] If the oil and gas saturation in the oil and gas reservoir is ≥50% and the tested oil and gas flow is industrial oil and gas flow, it is considered that oil and gas migration has occurred and reservoirs have formed.

[0039] In summary, under normal-to-weakly overpressure conditions, by combining the fault-sand ratio and fault-mud ratio, along with hydrocarbon shows, migration, and / or accumulation models, the mechanism by which fault-sand-caprock elements control migration and reservoir development is revealed. Therefore, a method for determining migration and reservoir control based on the combination of fault-sand-caprock elements is proposed.

[0040] The method provided by the present invention will be described below through specific embodiments.

[0041] Example

[0042] A method for determining transport and storage control based on the combination of fault-sand-cover elements includes the following steps;

[0043] The oil and gas reservoir was selected and determined to be an atmospheric-to-weakly overpressure system; where the pressure coefficient is the ratio of pore fluid pressure to hydrostatic pressure. An atmospheric-to-weakly overpressure system has a pressure coefficient between 0.9 and 1.2.

[0044] Identify faults in oil and gas reservoirs, and determine whether the faults are parallel or reverse faults.

[0045] In the embodiments of this application, when the fault is identified as a parallel fault, the fault-sand-cap elements of the parallel fault are tested, wherein the fault-sand-cap elements are the fault displacement, the thickness of a single sand body, and the thickness of the non-permeable mudstone body below the single sand body.

[0046] Subsequently, based on the fault-sand-cap elements, the ratio of fault displacement to sand body thickness (fault-sand ratio, Hf / Hs) was calculated to be greater than 1 or less than 1, and the ratio of fault displacement to non-permeable mudstone body thickness (fault-mud ratio, Hf / Hm) was calculated to be greater than 1 or less than 1.

[0047] The ratio of fault displacement to sand body thickness and the ratio of fault displacement to non-permeable mudstone body thickness are used to determine whether oil and gas migrate and / or accumulate in the oil and gas reservoir.

[0048] Among them, see Figure 1 As shown, the ratio of fault displacement to sand body thickness (fault-sand ratio, Hf / Hs) > 1, and the ratio of fault displacement to non-permeable mudstone body thickness (fault-mud ratio, Hf / Hm) < 1, indicate complete sand-mud contact, which is conducive to hydrocarbon accumulation. Among them, complete sand-mud contact means that the sand body at one end of the fault is in complete contact with the mudstone at the other end of the fault.

[0049] Alternatively, a fault displacement to sand body thickness ratio (fault-sand ratio, Hf / Hs) > 1, and a fault displacement to non-permeable mudstone body thickness ratio (fault-mud ratio, Hf / Hm) > 1, indicates partial sand-mud contact, which is conducive to hydrocarbon migration and reservoir formation; among them, full sand-mud contact refers to partial contact between the sand body at one end of the fault and the mudstone at the other end of the fault.

[0050] Alternatively, if the ratio of fault displacement to sand body thickness (fault-sand ratio, Hf / Hs) < 1, and the ratio of fault displacement to thickness of non-permeable mudstone body (fault-mud ratio, Hf / Hm) < 1, it indicates a sand-sand contact type, which is conducive to oil and gas migration and conduction, but not conducive to oil and gas accumulation; among them, sand-sand contact refers to the contact between the sand body at one end of the fault and the upper part of the sand body at the other end of the fault.

[0051] Alternatively, a fault displacement to sand body thickness ratio (fault-sand ratio, Hf / Hs) < 1, and a fault displacement to impermeable mudstone body thickness ratio (fault-mud ratio, Hf / Hm) > 1, indicates a sand-sand multi-connection pattern, which is conducive to hydrocarbon migration and transport but unfavorable to hydrocarbon accumulation and reservoir formation. Here, sand-sand multi-connection refers to multiple contacts between sand bodies at one end of a fault and sand bodies at the other end.

[0052] In the embodiments of this application, when the fault is identified as a reverse fault, the fault-sand-cap elements of the reverse fault are tested, including the fault displacement, the thickness of a single sand body in the oil and gas reservoir, and the thickness of the non-permeable mudstone body above the single sand body.

[0053] Subsequently, based on the fault-sand-cap elements, the ratio of fault displacement to sand body thickness (fault-sand ratio, Hf / Hs) was calculated to be greater than 1 or less than 1, and the ratio of fault displacement to non-permeable mudstone body thickness (fault-mud ratio, Hf / Hm) was calculated to be greater than 1 or less than 1.

[0054] The ratio of fault displacement to sand body thickness and the ratio of fault displacement to non-permeable mudstone body thickness are used to determine whether oil and gas migrate and / or accumulate in the oil and gas reservoir.

[0055] Among them, see Figure 1 As shown, the ratio of fault displacement to thickness of non-permeable mudstone body (fault-mudstone ratio, Hf / Hm) < 1, and the ratio of fault displacement to thickness of sandstone body (fault-sandstone ratio, Hf / Hs) > 1, indicating that the sandstone and mudstone are fully connected, which is conducive to hydrocarbon accumulation.

[0056] Alternatively, the ratio of fault displacement to thickness of non-permeable mudstone body (fault-mudstone ratio, Hf / Hm) < 1, and the ratio of fault displacement to thickness of sandstone body (fault-sandstone ratio, Hf / Hs) < 1, indicates partial sand-mudstone contact, which is conducive to hydrocarbon migration and reservoir formation.

[0057] Alternatively, if the ratio of fault displacement to the thickness of the impermeable mudstone body (fault-mudstone ratio, Hf / Hm) is greater than 1, and the ratio of fault displacement to the thickness of the sandstone body (fault-sandstone ratio, Hf / Hs) is greater than 1, it indicates a sand-sand-on-top connection type, which is conducive to the migration and conduction of oil and gas, but not conducive to the accumulation of oil and gas.

[0058] Alternatively, if the ratio of fault displacement to the thickness of the impermeable mudstone body (fault-mudstone ratio, Hf / Hm) is greater than 1, and the ratio of fault displacement to the thickness of the sandstone body is less than 1, it indicates a sand-sand multi-connection type, which is conducive to the migration and conduction of oil and gas, but not conducive to the accumulation and formation of oil and gas reservoirs.

[0059] In summary, this invention provides a method for controlling hydrocarbon migration and accumulation through the combination of fault-sand-caprock elements in an atmospheric-weak overpressure system, where the main controlling factors are hydrodynamics and the transport system. Under atmospheric-weak overpressure conditions, the combination of fault-sand-caprock elements becomes the primary factor controlling hydrocarbon migration and accumulation. This technical solution not only classifies faults but also considers the different combinations of multiple fault-sand and fault-caprock elements in controlling migration and accumulation. Faults are divided into perpendicular faults (faults dipping in the same direction as the strata) and reverse faults (faults dipping in the opposite direction to the strata). The difference lies in the combination of perpendicular faults (parallel faults) and mudstone in the lower sand body controlling migration and accumulation, while reverse faults (reverse faults) and mudstone in the upper sand body control migration and accumulation. The fault-sand ratio (fault displacement / single sand body thickness) and the fault-mud ratio (fault displacement / single mudstone thickness) are used to characterize the mechanism of controlling migration and accumulation through the combination of fault-sand-caprock elements under atmospheric-weak overpressure systems.

[0060] The main characteristics of fault-controlled migration and reservoir formation are: fault-sand ratio > 1 (Hf / Hs > 1); when fault-mud ratio < 1 (Hf / Hm < 1), it is characterized by full sand-mud contact, which is conducive to hydrocarbon accumulation; when fault-mud ratio > 1 (Hf / Hm > 1), it is characterized by partial sand-mud contact, which is conducive to hydrocarbon migration and accumulation; Hf / Hs < 1 and Hf / Hm < 1 are sand-sand top contact types, which are conducive to hydrocarbon migration and conduction but not conducive to hydrocarbon accumulation; Hf / Hs < 1 and Hf / Hm > 1 are sand-sand multi-contact types, which are conducive to hydrocarbon migration and conduction but not conducive to hydrocarbon accumulation.

[0061] Reverse fault-controlled migration and reservoir formation is mainly characterized by a fault-mud ratio <1 (Hf / Hm <1). When the fault-sand ratio >1 (Hf / Hs >1), it is characterized by full sand-mud contact, which is conducive to hydrocarbon accumulation. When the fault-sand ratio <1 (Hf / Hs <1), it is characterized by partial sand-mud contact, which is conducive to hydrocarbon migration and accumulation. The Hf / Hs >1 and Hf / Hm >1 types are sand-sand top contact types, which are conducive to hydrocarbon migration and conduction but not conducive to hydrocarbon accumulation. The Hf / Hs <1 and Hf / Hm >1 types are sand-sand multi-contact types, which are conducive to hydrocarbon migration and conduction but not conducive to hydrocarbon accumulation.

[0062] The specific embodiments described above illustrate the technical solution and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention, but it does not limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for judging the controlling of migration and accumulation by the combination of a sand- breaking cap element, characterized in that, The method comprises the following steps: selecting an oil and gas layer, and determining that the oil and gas layer is a normal pressure-weak overpressure system; identifying a fault in the oil and gas layer, and testing fault-sand-cap elements of the fault, wherein the fault-sand-cap elements are fault throw, sand body thickness and non-permeable mudstone thickness; then calculating a ratio of the fault throw to the sand body thickness > 1 or < 1, and a ratio of the fault throw to the non-permeable mudstone thickness > 1 or < 1 according to the fault-sand-cap elements; determining whether oil and gas migration and / or accumulation occurs in the oil and gas layer by the calculated ratio of the fault throw to the sand body thickness and the ratio of the fault throw to the non-permeable mudstone thickness; the normal pressure-weak overpressure system is a pressure coefficient of 0.9-1.2, wherein the pressure coefficient is a ratio of pore fluid pressure to hydrostatic pressure.

2. The method of judging the controlling of migration and accumulation of the combination of the sand-eliminating cap elements according to claim 1, characterized in that, The fault is a normal fault or a reverse fault.

3. The method of judging the controlling of migration and accumulation of the combination of the sand-eliminating cap elements according to claim 2, characterized in that, When the fault is a normal fault, the fault-sand-cap elements are fault throw, single set sand body thickness and single set sand lower non-permeable mudstone thickness.

4. The method according to claim 3, wherein, the ratio of the fault throw to the sand body thickness > 1 and the ratio of the fault throw to the non-permeable mudstone thickness < 1, which indicates sand-mud full contact and is beneficial to oil and gas accumulation; or, the ratio of the fault throw to the sand body thickness > 1 and the ratio of the fault throw to the non-permeable mudstone thickness > 1, which indicates sand-mud partial contact and is beneficial to oil and gas migration and accumulation; the ratio of the fault throw to the sand body thickness < 1 and the ratio of the fault throw to the non-permeable mudstone thickness < 1, which indicates sand-sand upper contact type and is beneficial to oil and gas migration and transport but not to oil and gas accumulation; or, the ratio of the fault throw to the sand body thickness < 1 and the ratio of the fault throw to the non-permeable mudstone thickness > 1, which indicates sand-sand multiple contact type and is beneficial to oil and gas migration and transport but not to oil and gas migration and accumulation.

5. The method of judging the controlling of migration and accumulation of the combination of the sand-eliminating cap elements according to claim 2, characterized in that, When the fault is a reverse fault, the fault-sand-cap elements are fault throw, single set sand body thickness of the oil and gas layer and single set sand upper non-permeable mudstone thickness.

6. The method according to claim 5, wherein, the ratio of the fault throw to the non-permeable mudstone thickness < 1 and the ratio of the fault throw to the sand body thickness > 1, which indicates sand-mud full contact and is beneficial to oil and gas accumulation; or, the ratio of the fault throw to the non-permeable mudstone thickness < 1 and the ratio of the fault throw to the sand body thickness < 1, which indicates sand-mud partial contact and is beneficial to oil and gas migration and accumulation; the ratio of the fault throw to the non-permeable mudstone thickness > 1 and the ratio of the fault throw to the sand body thickness > 1, which indicates sand-sand upper contact type and is beneficial to oil and gas migration and transport but not to oil and gas accumulation; or, the ratio of the fault throw to the non-permeable mudstone thickness > 1 and the ratio of the fault throw to the sand body thickness < 1, which indicates sand-sand multiple contact type and is beneficial to oil and gas migration and transport but not to oil and gas migration and accumulation.

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