RU2794388C1 - Method for optimizing oil prospecting - Google Patents

Abstract

FIELD: optimizing oil prospecting.

SUBSTANCE: method including an assessment of prospects for oil and gas potential of regional and local objects on the basis of seismic exploration. Known deposits are ranked by depth. The stepwise nature of the distribution of deposits is identified. Then the depths of the identified steps are determined, the seismic profiles are interpreted taking into account the identified depth characteristic of the given territory. When identifying structural and non-structural traps on seismic profiles within the identified depths, the object is recommended for exploratory drilling.

EFFECT: identifying specific depths on the territories where seismic exploration has been carried out at which it is possible to detect hydrocarbon deposits when seismic exploration at these depths identifies conditions for preserving hydrocarbon deposits.

1 cl, 2 tbl, 7 dwg

Description

Technical field

The invention relates to the field of geology and can be used in the search, exploration and development of minerals (gas, oil) to determine the location of the laying of prospecting and appraisal wells and the selection of objects in the context of the sedimentary cover productive for oil and gas formations.

Prerequisites for the creation of the invention

The active hydrocarbon system is determined by the geometry of the layers, the presence of reservoir rocks, overlying and underlying impermeable rock varieties (tires and impermeable rocks), the presence of high-quality (sapropel or humus) organic matter in the rocks, which, as the rocks sink to a depth under the influence of temperatures (process catagenesis), turns into hydrocarbons, filling the traps.

Used in practice, the standard methods of interpreting seismic data are aimed at identifying the presence and structural features of structural and non-structural traps capable of retaining hydrocarbons. Seismic methods in the course of work reveal several favorable structural forms in the study area (for example, a licensed area), which are recommended for drilling.

However, this approach results in low productivity. The success rate is not higher than 0.4, i.e. out of 10 drilled wells recommended by seismic survey, only 4 are productive.

Thus, when conducting seismic work for oil and gas, there is a high probability of not detecting structures with hydrocarbon deposits.

Publications that describe attempts to solve similar problems include the following.

Prior Art

A known method for detecting oil and gas deposits in a section opened by a well, including measuring the temperature along the wellbore, registering a thermogram and mathematical processing of the measurement results, while the thermogram is recorded by taking temperature measurements at different recording speeds, approximating the obtained geothermal curve with a polynomial of the first degree, according to geothermal data, a regression equation is calculated and a regression line is built, a section with a convex geothermal curve in relation to the calculated regression line is identified as an exothermic zone corresponding to the area of hydrocarbon generation and deposit formation, then temperature measurements are taken within the depths of the generation and deposit formation zones with a more fractional quantization step and when fixing an anomalous decrease in temperature, the boundary of the temperature decrease is identified as the contact of the hydrocarbon deposit with formation water (see patent for the invention of the Russian Federation No. 2743114, IPC E21B 47/07, G01V 9/00, publ. February 15, 2021).

The disadvantages of the known method include the fact that the proposed method of processing geothermal data is carried out in drilled wells, in which it is either planned to conduct temperature studies along the wellbore of the opened geological section, or these studies have been carried out.

There are known methods for detecting oil and gas deposits in the section based on the proven conjugation of hydrocarbon generation zones with the zones of formation of deposits and the integration of seismic exploration and methods of deep geochemistry [1,2,3,4]. The papers substantiate the theoretical base on the geochemistry of the organic matter of sedimentary rocks, the nature of the processes of oil and gas formation and the formation of hydrocarbon deposits. The theoretical basis for choosing rational solutions for oil exploration, as well as for other problems in the field of petroleum geology, is the following.

The processes of oil and gas formation in the oil cover have a complex, impulsive, quasi-periodic nature, accompanied by the phenomena of structural restructuring of kerogen, the emigration of hydrocarbons from the kerogen matrix, which leads to the formation of oil and gas deposits. This conclusion is based on a large amount of factual material on the chemical properties of kerogen isolated from the rocks of the Paleozoic age of the Caspian depression, on the nature of oil and gas manifestations (including deposits) and on the physicochemical properties of fluids.

Both in terrigenous and carbonate complexes, hydrocarbon deposits are confined to zones of their intensive generation, reflecting the focal nature of the formation of deposits, and do not coincide in depth: if the processes of generation of hydrocarbons and the formation of deposits are observed in carbonate complexes, then in terrigenous these processes are not observed. Therefore, the results of exploration work are the better, the more accurately the catagenetic zoning of organic matter is restored for the study area and the depths are revealed for the corresponding complexes where organic matter generated hydrocarbons and deposits were formed.

The work [5] is also used as an analog, in which the main directions for the integration of methods of deep geochemistry are outlined, reflecting the processes of generation and formation of oil and gas deposits.

The disadvantages of works [1-5] include the lack of knowledge of the issue of specific depths for various geological objects on which deposits can be formed, which leads to an increase in exploration costs in areas where seismic exploration has been carried out.

The work [3] was chosen as a prototype, in which one of the main tasks of seismogeochemical work is defined - to determine, if possible, the clearest criteria for the correlation of signs of seismic and geochemical anomalies, the simultaneous identification of which in the seismic and geochemical fields would significantly increase the reliability of the complex interpretation of all obtained data. data and reliability about the nature of saturation of the detected trap with hydrocarbons.

In the well-known work [3], the solution of these problems is presented in the creation of a single block for processing geochemical information and seismic work (seismic geochemical modeling). At the same time, seismic geochemical modeling consists of geophysical and geochemical blocks.

The geophysical block includes: standard processing and specialized processing of high-quality field material in order to trace the boundaries of the section; construction of a deep section with clearly defined seismological and lithological boundaries (for thick-layered media).

The geochemical block includes: restoration of types of organic matter; restoration of temperatures, paleotemperatures and catagenetic zoning; identification of zones of intensive hydrocarbon emigration and formation of deposits.

Zones of intensive hydrocarbon emigration and the formation of hydrocarbon deposits are determined in accordance with the type and catagenetic transformation of dispersed organic matter. The final result includes: a temporary seismic section with selected reference seismic-geological and temperature boundaries in the selected scale; the same with paleotemperature boundaries; the same with the boundaries of catagenesis.

The disadvantage of the prototype is the "regional" nature of the forecast of possible oil and gas content without answering questions about the specific depths at which oil and gas fields are being formed. The absence of an algorithm for applying this approach to different territories with different geological structures leads to an increase in exploration costs in the territories where seismic surveys have been carried out.

There is a need to create a way optimization of the search for hydrocarbon deposits formation zones, in areas with known oil and gas potential, where the search for oil and gas deposits continues. At the same time, optimization consists in determining the specific depths at which the process of generation and formation of hydrocarbon deposits takes place, which scans the entire data array to search for elements of the hydrocarbon system and displays a list of promising objects for their study by the interpreter. Preferably, this list of potential exploration targets is ordered by the expected volume, presence and quality of elements of the hydrocarbon system, and the reliability of their detection and identification. The present invention satisfies at least these requirements, and this problem is solved for all geological objects, characterized by the specificity of the geological structure.

Disclosure of invention

The objective of the present invention is to determine the optimal depths at which oil and gas deposits are formed before drilling in the study area.

The technical result achieved in solving this problem is the reduction of exploration costs by identifying in the territories where seismic exploration has been carried out, specific depths at which it is possible to detect hydrocarbon deposits when seismic surveys fix favorable conditions for the preservation of hydrocarbon deposits at these depths, i.e. the presence of structural and non-structural traps.

The specified technical result is achieved by the fact that in a method for optimizing oil exploration, including an assessment of the prospects for oil and gas potential of regional and local objects based on seismic exploration, according to the invention,known deposits are ranked by depth, the stepwise nature of the distribution of deposits is revealed, the depths of the identified stages are determined, the seismic profiles are interpreted taking into account the identified depths characteristic of the given territory, and, when favorable structural and non-structural traps are determined on the seismic profiles within the identified depths, they recommend the object for setting up a search drilling.

The causal relationship between the features of the invention and the achieved technical result lies in the fact that the formation of hydrocarbon deposits is closely related to the course of the transformation of organic matter into hydrocarbons, the process proceeds discretely, in impulses and is timed to certain temperature changes in the section of the sedimentary cover, which is associated with pigeons of immersion sedimentary rocks in the course of the geological development of the territory. This makes it possible to use this regularity in solving problems of oil prospecting geology.

Ranking known deposits by depth makes it possible to identify the stepwise nature of the distribution of deposits.

Determining the depth of the identified steps makes it possible to recommend these depths when interpreting seismic data in order to identify structural and non-structural forms for the preservation of deposits.

Interpretation of seismic profiles makes it possible to determine favorable structural and non-structural traps within the identified depths for further recommendation of the target for exploratory drilling.

Brief description of the drawings

The essence of the invention is illustrated by drawings, where:

in fig. 1 shows a fragment of the map of deposits in the study area within large tectonic elements: the Voronezh anteclise, the Ryazan-Saratov megatrough, the Volga-Ural anteclise and the northwestern framing of the Caspian depression;

in fig. 2 - territory of seismic geochemical profiling;

in fig. 3 - an example of a geological section according to seismic data, while showing along the abscissa - the length of the profile in accordance with figure 2, along the ordinate - the depth of the geological section, characterized by seismic;

in fig. 4 - section of catagenetic zonality, with PK - protocatagenesis; MK - mesocatagenesis (where 1-4 substages); A.B, C, D - salt domes;

in fig. 5 - according to [6], the distribution of oil, gas and condensate reserves in the sedimentary cover, in particular ancient platforms, depending on the degree of catagenesis of organic matter is shown, while the abscissa shows -%, the ordinate shows the stages of catagenesis;

in fig. 6 - an example of a stepped distribution of deposits by depth (according to table. 2), while the abscissa shows the numbers of hydrocarbon deposits in accordance with table. 2, along the y-axis, the depths of deposits, m;

in fig. 7 - distribution of oil and gas fields (more than 100 objects) by depths within the identified tectonic structures, while the abscissa shows the fields (without names), the ordinate shows the depths of the fields, m.

The proposed method is implemented as follows.

When using a method for optimizing oil prospecting, including an assessment of the prospects for oil and gas potential of regional and local objects based on a data bank on fields, known fields are ranked by depth, the stepwise nature of the distribution of fields is revealed, and the depths of the identified steps are determined.

Then, seismic profiles are interpreted taking into account the identified depths characteristic of a given territory and, when favorable structural and non-structural forms of the earth's crust layers (traps for hydrocarbons) are determined on the seismic profiles within the identified depths, the object is recommended for exploratory drilling.

The map (Fig. 1) shows a complex tectonic knot (along the crystalline basement), consisting of several large tectonic elements (the Voronezh anteclise, the Ryazan-Saratov megatrough, the Volga-Ural anteclise, and the northwestern framing of the Caspian megadepression), which are complicated by structures in the upper floors sedimentary cover and are reflected in the names. A databank (more than 100 objects) was compiled for these fields, which was used to identify the features of the distribution of productive layers by depth.

The invention is illustrated by the following example.

An example of an algorithm for solving a problem.

A seismic survey was carried out along the studied profile, while seismic geochemical profiling is shown in Fig. 2.

Based on the seismic survey data, a geological section was obtained, shown in Fig. 3.

According to the data of the geotemperature gradient for this area and paleotemperatures, the profile is presented in the form of catagenetic zonality of organic matter, which is contained in the sedimentary rocks of the profile under consideration (Fig. 4).

According to [6] hydrocarbon reserves are closely related to the zones of catagenesis of organic matter of lithological-stratigraphic complexes (figure 5).

The tasks of seismogeochemical profiling in the example under consideration are solved from the point of view of assessing the possible generation of hydrocarbons in the studied lithological-stratigraphic complex, finding in the section areas that are most favorable for the formation of deposits.

Since the formation of hydrocarbon deposits occurs, albeit on a different scale, at almost all stages of catagenesis, and especially in the zone of oil and gas production (the main phase of oil and gas formation), it is important to more accurately know the depths at which deposits are formed. This problem is solved in the present invention.

The problem of optimizing oil prospecting was solved on the basis of a data bank on the fields of the Saratov and Volgograd regions (Fig. 1), which was created over several decades. The data bank included a lot of information on geology, phase composition of fluids and their properties, hydrochemical characteristics of formation waters of these fields. An analysis of the depths of formation of deposits revealed the special conditions that form the basis of the invention.

Based on the database, a fragment of the data bank for the fields of the Saratov and Volgograd regions is shown, shown in Table 1.

Table 1 Areas within the Ryazan-Saratov megatrough tectonic element Fluid Geological age collector type Depth, m Surovskoe 3 Oil C2ml Carbonate. 521 Zubovskoe 1 Oil C1bb Terrigen. 1394 Papanovskoe 1 Oil D3sm Carbonate. 1402 Slonovskoe 1 Oil D3ps+D3tm Terrigen. 1900 Yazykovskoe 1 Gas C1tl Terrigen. 1148 Yazykovskoe 1 Gas C1bb Terrigen. 1159 Yazykovskoye 1 Oil C1bb Terrigen. 1160 Yazykovskoye 1 Oil C1bb Terrigen. 1167 Yazykovskoe 1 Oil C1tl Terrigen. 1170 Yazykovskoye 1 Oil C1tl Terrigen.. 1139 Kazanlinskoe 2 Oil Gas C1ksl Carbonate. 740 Elshano-Kurdyum 3 Gas C1crp - C1ksl - C1bb Terrigen. 800 Elshano-Kurdyum 3 Oil C1ksl Terrigen. 850 Surovskoe 3 Oil C2prk - C2crm Carbonate. 530 Surovskoe 3 Oil C1tl Terrigen. 1124 Lugovoe 4 Oil cond C1bb Terrigen. 2562 Lugovoe 4 Oil cond C1crp - C1ksl Carbonate. 2603 Lugovoe 4 Oil D3ev - D3lv Carbonate. 3088 Lugovoe 4 Gas C1bb Terrigen. 2831 Razinskoe 4 cond Gas D2vor Terrigen. 2888 Razinskoe 4 cond C1bb Terrigen. 2835 Razinskoye 4 Gas C2prk C2crm Carbonate. 1446 Akhmat 5 Oil D2ms Carbonate. 2835 White stone 5 Oil C1bb Terrigen. 2359 Berezovskoe 5 cond Gas C1bb Terrigen. 2391 Berezovskoe 5 cond Gas P1ar Carbonate. 1648 Berezovskoe 5 cond D2 Terrigen. 3752

Legend:

1 - Atkar uplift zone;

2 - Bazarno-Karabulak dislocation;

3 - Elshano-Sergievsky inversion shaft;

4 - Kamensko-Rovno monocline;

5 - Side monocline;

P1ar - Artinian;

C2mlk - C2mlk Melekesian;

C2prk - C2cr - C2prk - C2crm (Cheremshano-Prikamsky);

C1tl - C1tl Tula;

C1bb - C1bb Bobrikovskiy;

C1ksl - C1ksl Kizel;

C1crp - C1ksl - C1crp - C1ksl (Kizelovo-Cherepetsky);

C1crp - C1ksl - C1bb - C1crp - C1ksl - C1bb (beaver-kizelov - skull);

D3ev - D3lv - D3ev - D3lv Evlano-Liven;

D3sm - D3sm Semiluki;

D3ps + D3tm - D3ps + D3tm (Timan + Pashian);

D2vor - D2vor sparrow;

D2ms - D2ms Mosolovskie.

An example of normalization of deposits of deposits by depth as they increase (from Table 1) is shown in Table. 2.

table 2 Ordinal
number when rationing
in depth (Fig.2) squares Depth, m 1 Surovskoe 521 2 Zubovskoe 530 3 Papanovskoe 740 4 Slonovskoe 800 5 Yazykovskoye 850 6 Yazykovskoye 894 7 Yazykovskoye 1124 8 Yazykovskoe 1139 9 Yazykovskoe 1148 10 Yazykovskoe 1159 eleven Kazanlinskoe 1160 12 Elshano-Kurdyum 1167 13 Elshano-Kurdyum 1170 14 Surovskoe 1370 15 Surovskoe 1394 16 Surovskoe 1402 17 Lugovoe 1648 18 Lugovoe 1900 19 Lugovoe 2359 20 Lugovoe 2391 21 Razinskoe 2562 22 Razinskoye 2603 23 Razinskoye 2831 24 Akhmat 2835 25 White stone 2888 26 Berezovskoe 3088 27 Berezovskoe 3752

An example of plotting the distribution of hydrocarbon deposits by "normalized" depths using Table. 2 is shown in FIG. 6, where the stepwise nature of the distribution of hydrocarbon deposits in depth is clearly visible.

The results of processing the database for the entire study area (more than 100 deposits) are shown in Fig. 7, where the abscissa shows the deposits (without names), the ordinate shows the depths of the deposits, m.

The claimed invention can be industrially implemented using well-known technical means and find application in a territory with a known oil and gas potential, where geological exploration for oil and gas continues, while the stepwise nature of the formation of oil and gas deposits is determined. According to seismic exploration, structural and non-structural objects are revealed in the section of the sedimentary cover that are capable of retaining hydrocarbons. The depths of these objects are compared with the "steps" of the formation zones of deposits. If the depths of occurrence of the identified geological objects coincide with the "steps" of the zones of formation of deposits, this object is recommended for drilling.

The positive effect of using the proposed method is due to the location of the search for oil and gas in specific promising directions to determine the location of the laying of prospecting and appraisal wells and the selection of objects in the context of the sedimentary cover of oil and gas productive reservoirs, which makes it possible to achieve drilling success and this ultimately leads to reducing material costs for geological exploration and increasing their efficiency.

Information sources

1. Navrotsky, O.K. Evolutionary geochemical conditions for the generation of hydrocarbons and the formation of their deposits in subsalt deposits (on the example of the Caspian oil and gas province). Abstract dis…. Doctor of Geol.-Min. Sciences (04.00.92 and 04.00.17). – L.: VNIGRI. - 1990. - S. 48.

2. Navrotsky, O.K. Features of the transformation of insoluble organic matter in the process of catagenesis. // Subsoil of the Volga and Caspian regions. - Issue. 29. - Saratov. - 2000. - S.48-51.

3. Navrotsky O.K., Tikshaev V.V., Semenov V.N., Mikhailov V.A., Navrotsky A.O., Gontarev V.V. Experience in using the seismogeochemical method for predicting oil and gas potential. // Subsoil of the Volga and Caspian regions. - No. 7. - Saratov. - 1994. - S. 44–50.

4. Navrotsky O.K., Timofeev G.I., Navrotsky A.O. On the impulsive nature of the processes of oil and gas formation and the formation of hydrocarbon deposits. // Subsoil of the Volga and Caspian regions. - No. 55. - Saratov. - 2008. - S. 21-24.

5. Navrotsky O.K., Sidorov I.N., Navrotsky A.O. Improving the methodology for assessing the prospects for oil and gas potential of regional and local objects based on seismic exploration and deep geochemistry (seismic geochemical modeling). In book. New ideas in geology and geochemistry of oil and gas. To the creation of a general theory of oil and gas content of the bowels. Book. 2. / Ed. B.A. Sokolova, Ph.D. E.A. Ablya. - M.: GEOS. - 2002. - S. 36-39.

6. Catagenesis and oil and gas potential / Paraparova G.M., Neruchev S.T. and others - L.: Nedra. - 1981. - 240 p.

Claims (1)

A method for optimizing oil prospecting, including an assessment of the prospects for oil and gas potential of regional and local objects based on seismic exploration, characterized in that the known fields are ranked by depth, the stepped nature of the distribution of fields is revealed, the depths of the identified steps are determined, the seismic profiles are interpreted taking into account the identified depths characteristic of a given territory and , when determined on seismic profiles within the identified depths of structural and non-structural traps, the object is recommended for exploratory drilling.

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