RU2419111C2 - Method to detect permeability of terrigenous container rocks - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: core is picked, permeability is identified in the core. Electric logging of wells is carried out, and relative amplitude of natural electric potentials (PS) is identified. Correlation dependence of the relative PS amplitude is built on the core permeability. Additionally radioactive logging is carried out; hydrogen content is measured in the solid phase of the core, as well as its diffusion-adsorption activity, which is used to calculate the relative PS amplitude. Then kaolin content is measured in the core, using which, groups of container rocks are identified. The ratio of the solid phase hydrogen content to the relative PS amplitude in the core is calculated for each identified group. The correlation relation of this ratio and kaolin content in the core is built, and the dependence α_nc=f(K_np) in the core is built for each identified group of containers. Then the solid phase hydrogen content ratio to the relative PS amplitude calculated based on the data of wells geophysical survey (GIS) is built, and using this ratio, groups of container rocks are identified. Permeability of container rocks is identified using values α_nc calculated by GIS data, using dependence α_nc=f(K_np) established in the core.

EFFECT: increased accuracy of terrigenous container rocks permeability detection.

4 dwg

Description

The invention relates to the field of geophysical research of wells and can be used to determine the permeability of rocks in wells drilled for oil, gas or water.

A known method for determining the permeability of rocks, based on the method of natural electric potentials (PS) / 1 /. In this method, rock permeability is determined by hydrodynamic studies.

However, the known method does not take into account the peculiarities of the mineralogical composition of rocks and, first of all, their clay cement, which significantly reduces the reliability of determining permeability.

The closest technical solution to the claimed invention is a method for determining the permeability of rocks according to the results of the method of natural electric potentials (PS), including core sampling, determination of permeability by core, determination of the relative amplitude of PS, the construction of a correlation of the relative amplitude of PS from permeability by core / 2 /.

In sedimentary rocks, the pores of which are saturated with water or oil, permeability is determined according to the PS method. To determine the permeability (K _ol ), correlation relationships of the form α _ps = f (K _ol ) are used, which are built for each specific area. The value of α _{ps is} calculated from the relation

where ΔU _{ps op} is the limit value of the amplitude ΔU _ps in the reservoir with known high permeability.

Values ΔU _ps , counted against the studied reservoirs and used to calculate α _ps , previously lead to readings in the reservoir of unlimited thickness ΔU _ps ^∞ . Permeability is determined by representative core taking into account thermobaric conditions characteristic of the studied field, or according to hydrodynamic studies. The physical prerequisite for using the method of natural electric potentials (PS) in assessing K _ol is the relationship of the diffusion-adsorption activity of rock A _{da ps} with its clay content.

The disadvantage of this method is the low reliability of determining permeability, since it does not take into account the composition and amount of clay minerals included in the cement of reservoir rocks. It is known that the following clay minerals prevail in the cement of non-carbonate reservoirs - montmorillonite, hydromica, chlorite, kaolinite. It was found that with an increase in the content of kaolinite in the rock, its permeability increases / 3, 4, 5 /. This is explained by the fact that the grain size of authigenic kaolinite reaches the size of siltstone particles. The content of individual clay minerals is determined by X-ray analysis (XRD) on the core. In the presence of an expanded complex of geophysical well surveys (GIS) (spectrometric gamma method, carbon-oxygen method, gamma-gamma density and neutron methods), the content of clay minerals can be estimated / 4 /. However, in most exploration and production wells, a traditional, generally accepted well logging system is carried out, which should be guided in the development of the proposed method for determining permeability.

The technical result achieved by using the present invention is to improve the accuracy and reliability of determining the permeability of terrigenous reservoir rocks.

The technical result achieved is achieved by the fact that the method for determining the permeability of terrigenous rocks-reservoirs includes conducting electrical logging of wells, core sampling, determining core permeability, determining the relative amplitude of the subsurface, building a correlation between the relative amplitude of the subsurface and the core permeability, additional conducting radioactive logging, measuring the hydrogen content of the core solid phase and the diffusion-adsorption activity of the core, according to which the relative PS core amplitude, the kaolinite content in the core is measured, by which groups of reservoir rocks are distinguished, for each selected group of reservoir rocks, the ratio of the hydrogen content of the solid phase to the relative PS amplitude of the core is calculated and the correlation of this ratio with the kaolinite content in the core is built, for each selected group of collectors is plotted α _ps = f (K _etc.) from the core is determined hydrogen content ratio of the solid phase relative to the amplitude of the SS, calculated by log data, and the largest e th relationships define groups of reservoir rocks, rock permeability which is determined by the values of α _ps calculated for the GIS data, respectively, using the relation α _ps = f (K _etc.) mounted on the cores.

A comparative analysis of the essential features of the proposed solution and the prototype allows us to conclude that the claimed invention meets the criterion of "novelty."

The claimed invention meets the criterion of "inventive step", as it clearly does not follow from the prior art.

The drawings show the following illustrations:

figure 1 presents the selection of collectors for the content of kaolinite;

figure 2 is a generalized dependence of the coefficient of permeability on the coefficient of porosity;

figure 3 - correlation of the form α _ps = f (K _CR );

figure 4 - correlation dependence of the ratio of W _TV / α _ps .

The method is as follows. In the process of analyzing geological and geophysical materials for hydrocarbon deposits in Western Siberia, three groups of reservoirs are identified by the kaolinite content. For example, in the first group, the content of kaolinite is more than 70-75%, in the second - 40-45-70-75% and in the third - less than 40-45% (Fig. 1). For each group of reservoirs, generalized dependences of the permeability coefficient on the porosity coefficient are constructed (Fig. 2). Similarly, for each group of collectors, the dependence α _ps = f (K _ol ) is built.

In the process of laboratory studies, the hydrogen content of the solid phase (W _tv ), diffusion-adsorption activity (A _yes ), porosity and permeability coefficients, clay mineral content are measured, three groups of reservoirs are preliminarily determined by the kaolinite content and correlation relationships of the form α _ps = f (K _pr ) for each group of collectors (figure 3). In this case, the relative amplitude of the PS is calculated by the formula

A _yes , A _yes ^max, respectively, diffusion-adsorption activity in the core sample and core sample with its maximum value in mV.

Calculate the ratio of the hydrogen content of the solid phase to the relative amplitude of the PS core W _TV / α _ps , build a correlation of this relationship with the content of kaolinite (figure 4). Collector groups are distinguished by the ratio W _tv / α _ps .

So, for example, for the Yu1 layer of the Khokhryakovsky deposit in Western Siberia, the first group corresponds to W _TV / α _ps less than 0.1, the second group - 0.1-0.25, the third group - 0.25-0.35.

Well studies are carried out by neutron, gamma and gamma methods and PS. According to the neutron method, the total hydrogen content (W _Σ ) is determined either by the double difference parameter or by the method of statistical normalization. Calculate porosity according to gamma-gamma density logging (GGKP)

where δ _m , δ _p , δ _f - respectively, mineralogical density, bulk and fluid density, g / cm ³ . The porosity coefficient is also determined by core or other existing methods. Next, the hydrogen content of the solid phase is calculated according to the GIS according to the formula

In the intervals of the collectors determine the relative anomaly of the PS - α _ps . The ratio W _tv / α _{ps is} calculated, by the value of which the collector group is determined and, accordingly, the dependence α _ps = f (K _ol ) is selected, which determines the permeability coefficient.

Thus, the accuracy and reliability of determining the permeability are increased, which makes it possible to construct refined petrophysical models of reservoirs necessary for the exploration and development of hydrocarbon deposits. In addition, the scope of the method is expanding, since it can be used for all types of reservoir rocks.

Sources of information taken into account when preparing an application for an invention.

1. Dakhnov V.N. "Geophysical methods for determining reservoir properties and oil and gas saturation of rocks." M .: "Nedra," 1975, p. 344.

2. Wendelstein B.Yu., Zoloeva G.M., Tsareva N.V. "Geophysical methods for studying computational parameters in determining oil and gas reserves." M .: "Nedra", 1985, p.248.

3. Ushatinsky I.N., Zaripov O.G. "Mineralogical and geophysical indicators of the oil and gas potential of the Mesozoic sediments of the West Siberian Plate." "Proceedings of ZapSibNIGNI", 1978, issue 96, p.208.

4. Khabarov V.V. "The search for clay minerals on the petrophysical and geophysical characteristics of reservoirs." Collection of scientific papers of the “Association of Developers and Users of Computer Technologies and the Interpretation of Geological and Geophysical Data. Problems of interpretation of GIS data on a computer. " Tyumen, 1992, p. 110-117.

5. Shpurov I.V., Timchuk A.S., Fedorov K.M., Khabarov V.V. "The methodology for constructing petrophysical models for Jurassic deposits on the example of the Khokhryakovsky field." “Oil industry”, Moscow, 2007, No. 1, p.22-24.

Claims (1)

A method for determining the permeability of terrigenous rocks-reservoirs, including conducting electrical logging of wells, core sampling, determining core permeability, determining the relative amplitude of natural electrical potentials (PS), building a correlation between the relative amplitude of PS and core permeability, characterized in that they additionally conduct radioactive logging, measure the hydrogen content of the core solid phase and the diffusion-adsorption activity of the core, from which the relative the core amplitude of the PS in the core, the kaolinite content in the core is measured, by which groups of reservoir rocks are distinguished, for each selected group of reservoir rocks, the ratio of the hydrogen content of the solid phase to the relative amplitude of the PS in the core is calculated and the correlation of this ratio with the kaolinite content in the core is built, For each selected group of reservoirs, the dependence α _ps = f (K _CR ) is built from the core, the ratio of the hydrogen content of the solid phase to the relative amplitude of the PS calculated according to the geophysical data is determined wells (GIS), and the value of this ratio determines the group of reservoir rocks for which the permeability of the rocks is determined by the values of α _ps calculated according to the well log data, respectively, using the dependence α _ps = f (K _CR ), established by core.

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