A method and apparatus for determining properties of carbonate rock diagenetic fluids

Abstract

The present application relates to a method and device for determining the property of carbonate rock diagenetic fluid. The method comprises the following steps: collecting a carbonate rock sample, determining the diagenetic period of the carbonate rock sample; determining the ratio range of the target isotope of the contemporaneous seawater according to the diagenetic period; determining the measured ratio of the target isotope of the carbonate rock sample, and comparing it with the ratio range to determine the diagenetic fluid property of the carbonate rock sample. The method uses existing data accumulation to determine the diagenetic fluid property of the carbonate rock sample in a fast and low-cost manner through the collection of a small amount of carbonate rock sample. The method can be well applied to various types of carbonate rock reservoirs. The property of the carbonate rock reservoir fluid can be accurately identified, thereby helping to find the favorable reservoir development area.

Description

Technical Field

[0001] This invention relates to the field of petroleum and natural gas geological exploration technology, specifically to a method and apparatus for determining the properties of diagenetic fluids in carbonate rocks. Background Technology

[0002] Carbonate reservoirs are among the most important types of oil and gas reservoirs. The formation and evolution of carbonate reservoirs are inseparable from fluid activity, and analyzing the mechanisms of fluid action is crucial for studying carbonate reservoirs. Therefore, researchers have employed numerous techniques to analyze the source, properties, and timing of fluids. The source and properties of fluids in carbonate reservoirs control the manner of fluid action, as well as the intensity and outcome of fluid flow, ultimately influencing the formation and maintenance of carbonate reservoirs.

[0003] Existing technologies offer numerous methods for studying the properties of diagenetic fluids in carbonate reservoirs. These include petrological and mineralogical analyses such as thin-section microscopy, cathodoluminescence, and electron probe microanalysis, as well as elemental analyses (iron, manganese, strontium content and oxygen, carbon, strontium isotope geochemical analysis) and fluid inclusion analysis. These methods encompass a wide range of research directions and techniques. Furthermore, most published literature utilizes a comprehensive approach combining petrological, mineralogical, and geochemical methods to determine the properties of diagenetic fluids in carbonate reservoirs.

[0004] Although there is a wealth of research on the fluid properties in carbonate rocks both domestically and internationally, and the corresponding technologies are relatively mature, analyzing diagenetic fluids in carbonate reservoirs requires collecting a large number of samples and conducting multiple and varied experiments. This demands significant manpower and resources. Furthermore, it requires researchers to possess specialized and comprehensive knowledge. Summary of the Invention

[0005] In view of the above-mentioned problems in the prior art, the present invention provides a method and apparatus for determining the properties of diagenetic fluids in carbonate rocks, which can quickly determine the properties of diagenetic fluids in carbonate reservoirs, thereby helping to find favorable reservoir development areas.

[0006] A first aspect of the present invention provides a method for determining the properties of diagenetic fluids in carbonate rocks, comprising the following steps:

[0007] Step S1: Collect carbonate rock samples and determine the diagenetic period of the carbonate rock samples;

[0008] Step S2: Determine the range of target isotope ratios for seawater during the same period based on the diagenetic period;

[0009] Step S3: Sample several minerals in the carbonate rock sample to obtain the measurement ratio of the target isotope of each mineral;

[0010] Step S4: Based on the measured ratio and the ratio range, determine the diagenetic fluid properties of the carbonate rock sample.

[0011] Furthermore, in step S2, the target isotope is the strontium isotope Sr. 87 and Sr 86 .

[0012] Furthermore, the two endpoints of the ratio range are a first endpoint value and a second endpoint value, respectively, with the first endpoint value being less than the second endpoint value.

[0013] Furthermore, the first endpoint value and the second endpoint value are 0.707910 and 0.708990, respectively.

[0014] Furthermore, the first endpoint value and the second endpoint value are 0.707156 and 0.707567, respectively.

[0015] A second aspect of the present invention provides an apparatus for determining the properties of diagenetic fluids in carbonate rocks, for use in any of the methods described above, comprising a graduated caliper and a first pointer, a second pointer, and a third pointer disposed on the caliper, wherein the first pointer, the second pointer, and the third pointer are all configured to slide along the length direction of the caliper so that the positional relationship of the first pointer, the second pointer, and the third pointer when they respectively indicate different values ​​of the graduations determines the properties of the diagenetic fluids in the carbonate rock sample.

[0016] Furthermore, the caliper has a first end and a second end, and the value of the scale increases sequentially from the first end to the second end.

[0017] Furthermore, the caliper is provided with a sliding groove extending along the length direction, the sliding groove being configured to allow the first pointer, the second pointer and the third pointer to slide along the length direction of the caliper.

[0018] Furthermore, there are two slides, with the first pointer and the second pointer located in the same slide, and the third pointer located in another slide.

[0019] Furthermore, the value of the scale is the endpoint value of the ratio range.

[0020] The beneficial effects of this invention are as follows: The method provided by this invention for determining the properties of diagenetic fluids in carbonate rocks includes the following steps: collecting carbonate rock samples; determining the diagenetic period of the carbonate rock samples; determining the ratio range of target isotopes of seawater during the same period based on the diagenetic period; measuring the measured ratio of the target isotopes in the carbonate rock samples and comparing it with the ratio range to determine the properties of the diagenetic fluids in the carbonate rock samples. This method utilizes existing data accumulation and, with a small number of collected carbonate rock samples, quickly and at a low cost, determines the properties of the diagenetic fluids in carbonate rock samples. This method can be well applied to various types of carbonate rock reservoirs. It can accurately identify the properties of carbonate rock reservoir fluids, thereby helping to find favorable reservoir development areas. Furthermore, the device provided by this invention for determining the properties of diagenetic fluids in carbonate rocks makes the entire determination process more convenient and intuitive. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] Figure 1 The diagram shows a flowchart of a method for determining the properties of diagenetic fluids in carbonate rocks.

[0023] Figure 2 The diagram shows a schematic of a device for determining the properties of diagenetic fluids in carbonate rocks.

[0024] The reference numerals in the figure are as follows: 10, caliper; 101, first end; 102, second end; 103, slide; 104, scale; 11, first pointer; 12, second pointer; 13, third pointer. Detailed Implementation

[0025] To make the technical problem to be solved, the technical solution, and the beneficial effects of this invention clearer, the invention will now be described in detail with reference to the accompanying drawings. This drawing is a simplified schematic diagram, illustrating only the basic structure of the invention, and therefore only shows the components relevant to the invention. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0026] refer to Figure 1 As shown, the method for determining the properties of diagenetic fluids in carbonate rocks provided by the present invention includes the following steps.

[0027] In step S1, carbonate rock samples are collected to determine the diagenetic period of the carbonate rock samples.

[0028] In some embodiments, the carbonate rock sample may be a rock collected by researchers on the surface, or a core obtained by researchers at different underground depths during geological exploration drilling.

[0029] In some embodiments, because the crystal shapes of diagenetic minerals from different periods are different, and the time at which diagenetic minerals from different periods fill the dissolution pores, cavities, or fissures is also different, the type and order of the diagenetic minerals filling the dissolution pores, cavities, or fissures in the carbonate rock sample can be identified by microscopic observation, thereby determining the diagenetic period of the carbonate rock sample.

[0030] In some implementations, researchers can grind carbonate rock samples collected from different strata into thin sections, then observe the characteristics of these sections to comprehensively determine the mineral types in the carbonate rock samples, and determine the formation sequence of the minerals based on metasomatic relationships. This allows for a relatively accurate determination of the diagenetic period of the carbonate rock samples.

[0031] The characteristics of the thin film include crystal size, crystal form, and luminescence when installed in a cathodoluminescence analyzer. Crystal size includes mud crystals, powder crystals, fine crystals, medium crystals, and coarse crystals. Crystal form includes euhedral, subhedral, and anhedral. Luminescence includes no luminescence, red, orange, and yellow.

[0032] In step S2, the range of target isotope ratios for seawater during the same period is determined based on the diagenetic period.

[0033] In some embodiments, the target isotope may be the strontium isotope Sr. 87 and Sr 86 The two endpoints of the ratio range are the first endpoint value and the second endpoint value, respectively. The first endpoint value is less than the second endpoint value.

[0034] In step S3, several minerals in the carbonate rock sample are sampled to obtain the measurement ratio of the target isotope of each mineral.

[0035] In step S4, the diagenetic fluid properties of the carbonate rock sample are determined based on the measured ratio and the ratio range.

[0036] In some embodiments, if the measured ratio is less than the first endpoint value, it indicates that mantle-derived fluids were involved in the diagenetic fluids of the carbonate rock sample.

[0037] In some embodiments, if the measured ratio is between the first endpoint value and the second endpoint value, it indicates that the diagenetic fluid of the carbonate rock sample was seawater during the diagenetic period.

[0038] In some embodiments, if the measured ratio is greater than the second endpoint value, it indicates that the diagenetic fluid of the carbonate rock sample was influenced by terrestrial atmospheric precipitation.

[0039] In some embodiments, the evolution of the diagenetic fluids in the carbonate rock sample can also be determined based on the measured ratios of the various minerals.

[0040] The method for determining the properties of diagenetic fluids in carbonate rocks will be described below through specific examples.

[0041] Example 1

[0042] The formation of the Majiagou Formation reservoir is primarily influenced by karstification, and its distribution is similarly affected. Researchers can use petrological and geochemical methods to understand the impact of atmospheric precipitation on the strata during karstification. However, re-emphasizing these methods to determine whether the Majiagou Formation reservoir in a newly explored area was also affected by karstification caused by terrestrial atmospheric precipitation would require a significant investment of time and resources. Therefore, determining the diagenetic fluid properties of carbonate rocks in a newly explored Majiagou Formation reservoir involves the following steps.

[0043] In step S101, carbonate rock samples are obtained from the F1 reservoir section of the Majiagou Formation by drilling and sampling to determine the diagenetic period of the carbonate rock samples.

[0044] In step S102, the strontium isotope Sr of the seawater during the diagenetic period is obtained by consulting existing relevant data. 87 / Sr 86 The ratio range. The first and second endpoints of the ratio range are 0.707910 and 0.708990, respectively.

[0045] In step S103, several minerals in the carbonate rock sample are sampled, and the strontium isotope Sr of each mineral is determined. 87 / Sr 86 The ratio of the measured values.

[0046] In step S104, the measured ratios of each of the minerals are all greater than the second endpoint of the ratio range. Therefore, it can be determined that the diagenetic fluids of the carbonate rock samples in the F1 reservoir section of the Majiagou Formation were influenced by terrestrial precipitation.

[0047] Example 2

[0048] The formation and evolution of Permian reservoirs are influenced by high-temperature fluids. Researchers can use petrological and geochemical methods to identify the origin of these fluids as seawater, terrestrial precipitation, or mantle-derived fluids. However, re-emphasizing petrological and geochemical methods to determine which hydrothermal fluids influenced the Permian reservoirs in a newly explored area would require a significant investment of time and resources. Therefore, determining the diagenetic fluid nature of carbonate rocks in a newly explored Permian reservoir involves the following steps.

[0049] In step S201, carbonate rock samples are obtained from the X2 reservoir section of the Permian reservoir through drilling and sampling to determine the diagenetic period of the carbonate rock samples.

[0050] In step S202, the strontium isotope Sr of the seawater during the diagenetic period is obtained by consulting existing relevant data. 87 / Sr 86 The ratio range. The first endpoint and the second endpoint of the ratio range are 0.707156 and 0.707567, respectively.

[0051] In step S203, several minerals in the carbonate rock sample are sampled, and the strontium isotope Sr of each mineral is determined. 87 / Sr 86 The ratio of the measured values.

[0052] In step S104, the measured ratios of each of the minerals are all greater than the second endpoint of the ratio range. Therefore, it can be determined that the diagenetic fluids of the carbonate rock samples in the X2 reservoir section of the Permian reservoir were influenced by terrestrial precipitation.

[0053] Based on the above method, the present invention also provides an apparatus for determining the properties of diagenetic fluids in carbonate rocks. The apparatus includes a caliper 10 with graduations 104, and a first pointer 11, a second pointer 12, and a third pointer 13 disposed on the caliper 10. The two ends of the caliper 10 are a first end 101 and a second end 102, respectively. The graduations 104 are marked on the edge of the caliper 10 along its length, and the values ​​of the graduations 104 are the strontium isotopes (Sr) of seawater at various diagenetic stages from existing relevant data. 87 / Sr 86 The endpoint values ​​of the ratio range. In some embodiments, the value of scale 104 increases sequentially in the direction from the first end 101 to the second end 102.

[0054] In some embodiments, the caliper 10 is made of a rigid material, such as rigid plastic or metal.

[0055] In some embodiments, the first pointer 11, the second pointer 12, and the third pointer 13 are all configured to slide along the length of the caliper 10 to indicate different values ​​of the scale 104. In some embodiments, the caliper 10 is provided with a groove 103 extending along its length. The first pointer 11, the second pointer 12, and the third pointer 13 are all positioned within the groove 103 in a direction perpendicular to the surface of the scale 104 on the caliper 10, so that the first pointer 11, the second pointer 12, and the third pointer 13 can slide along the groove 103. In some embodiments not shown, two grooves 103 are provided. The first pointer 11 and the second pointer 12 are located in the same groove 103, while the third pointer 13 is located in another groove 103.

[0056] In some embodiments, when using this device to determine the properties of the diagenetic fluid in carbonate rocks, a first pointer 11 indicates the first endpoint value, a second pointer 12 indicates the second endpoint value, and a third pointer 13 indicates the measured ratio. If the third pointer 13 is located between the first endpoint 101 and the first pointer 11, it indicates that mantle-derived fluids were involved in the diagenetic fluid of the carbonate rock sample. If the third pointer 13 is located between the first pointer 11 and the second pointer 12, it indicates that the diagenetic fluid of the carbonate rock sample was seawater from the diagenetic period. If the third pointer 13 is located between the second pointer 12 and the second endpoint 102, it indicates that the diagenetic fluid of the carbonate rock sample was influenced by terrestrial precipitation.

[0057] The beneficial effects of the method for determining the properties of diagenetic fluids in carbonate rocks provided by this invention are as follows: It includes the following steps: collecting carbonate rock samples; determining the diagenetic period of the carbonate rock samples; determining the ratio range of target isotopes of seawater during the same period based on the diagenetic period; measuring the measured ratio of the target isotopes in the carbonate rock samples and comparing it with the ratio range to determine the properties of the diagenetic fluids in the carbonate rock samples. This method utilizes existing data accumulation and, with a small number of collected carbonate rock samples, quickly and at a low cost, determines the properties of the diagenetic fluids in carbonate rock samples. This method can be well applied to various types of carbonate rock reservoirs. It can accurately identify the properties of carbonate rock reservoir fluids, thereby helping to find favorable reservoir development areas. Furthermore, the device provided by this invention for determining the properties of diagenetic fluids in carbonate rocks makes the entire determination process more convenient and intuitive.

[0058] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0059] It should be understood that the terms "length", "width", "up", "down", "front and back", "left and right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0060] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for determining the properties of diagenetic fluids in carbonate rocks, comprising the following steps: Step S1: Collect carbonate rock samples and determine the diagenetic period of the carbonate rock samples; Step S2: Determine the range of target isotope ratios for seawater during the same period based on the diagenetic period; Step S3: Sample several minerals in the carbonate rock sample to obtain the measurement ratio of the target isotope of each mineral; Step S4: Based on the measured ratio and the ratio range, determine the diagenetic fluid properties of the carbonate rock sample.

2. The method for determining the properties of diagenetic fluids in carbonate rocks according to claim 1, characterized in that, In step S2, the target isotope is the strontium isotope Sr. 87 and Sr 86 .

3. The method for determining the properties of diagenetic fluids in carbonate rocks according to claim 2, characterized in that, The two endpoints of the ratio range are the first endpoint value and the second endpoint value, respectively, and the first endpoint value is less than the second endpoint value.

4. The method for determining the properties of diagenetic fluids in carbonate rocks according to claim 3, characterized in that, The first endpoint value and the second endpoint value are 0.707910 and 0.708990, respectively.

5. The method for determining the properties of diagenetic fluids in carbonate rocks according to claim 3, characterized in that, The first endpoint value and the second endpoint value are 0.707156 and 0.707567, respectively.

6. An apparatus for determining the properties of diagenetic fluids in carbonate rocks, characterized in that, The method according to any one of claims 1-5 includes a caliper (10) having a scale (104) and a first pointer (11), a second pointer (12) and a third pointer (13) disposed on the caliper (10), the first pointer (11), the second pointer (12) and the third pointer (13) being configured to slide along the length direction of the caliper (10) so that the positional relationship when the first pointer (11), the second pointer (12) and the third pointer (13) respectively indicate different values ​​of the scale determines the diagenetic fluid properties of the carbonate rock sample.

7. The apparatus for determining the properties of diagenetic fluids in carbonate rocks according to claim 6, characterized in that, The caliper (10) has a first end (101) and a second end (102), and the value of the scale (104) increases sequentially from the first end (101) to the second end (102).

8. The apparatus for determining the properties of diagenetic fluids in carbonate rocks according to claim 7, characterized in that, The caliper (10) is provided with a slide groove (103) extending along the length direction, the slide groove (103) being configured to allow the first pointer (11), the second pointer (12) and the third pointer (13) to slide along the length direction of the caliper (10).

9. The apparatus for determining the properties of diagenetic fluids in carbonate rocks according to claim 8, characterized in that, There are two slides (103), with the first pointer (11) and the second pointer (12) located in the same slide (103), and the third pointer (13) located in another slide (103).

10. The apparatus for determining the properties of diagenetic fluids in carbonate rocks according to claim 7, characterized in that, The value of the scale (104) is the endpoint value of the ratio range.

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