KR20170121546A - Method for predicting exploitation site of unconventional resources applied to sequence stratigraphic analysis - Google Patents

Abstract

The present invention provides a method for effectively predicting an exploitation site of shale gas. According to the present invention, the method for predicting an exploitation site of shale gas comprises the following steps of: (S1) analyzing the total gamma ray (GR) in each depth in a drilling hole; (S2) analyzing a spectral gamma ray (SGR) of U, Th, and K elements in each depth in a drilling core; (S3) measuring and predicting the total organic carbon content (TOC) in each depth in the drilling core; and (S4) calculating acoustic impedance (AI) in the frilling hole.

Description

[0001] The present invention relates to a method for predicting non-traditional resources using a sequential stratified analysis,

The object of the present invention is to provide a method for predicting a non-traditional resource shale gas development zone, and more particularly, to a method of predicting a shale gas development zone in a shale layer, And a method for predicting a shale gas development zone in an economical manner based on the calculated results.

Shale gas, a non-traditional resource, has not been recognized as a useful resource compared to traditional resources for technological and economic reasons. However, with the development of hydraulic fracturing technique and the development of horizontal drilling, production efficiency has increased and shale gas development Has been realized and developed as a useful resource. Especially, as the development of horizontal drilling technology has been accelerated, the production of gas from the shale layer has become economical, and the development of shale gas has spread to many countries after USA and Canada.

The shale layer is a sedimentary rock formed by the deposition of fine grains containing clay and various minerals and is known to contain a large amount of organic matter depending on the deposition environment. The shale layer containing a lot of organic matter is known to be deposited in a place where the depth of the low energy environment is relatively deep, oxygen is lean or organic matter is generated. A shale layer containing a high content of organic matter can form a stratum together with a shale layer containing a low amount of organic matter, and the sedimentary layer containing organic matter during deposition will mature to form a kerogen-rich shale layer.

The formation of the shale layer can be explained by the change of relative sea level from the origin of the sediments determined by climatic conditions to the selective accumulation of coarse sediments in the sedimentation process and the deposition of clay sediments.

Generally, the shale layer is characterized by a porosity of less than 10% due to sediment and environment during sedimentation, and the permeability is less than 1 md, which is very dense and has poor fluidity.

In the beginning of the development of nontradical resources in the shale layer, the development of the shale layer as a relatively homogeneous sediment was considered to be more economical than the exploration work. However, shale layer characterization based on geochemistry and litho-mechanical properties became the key to the economical development and production of non-traditional shale resources, with variations in production even within the same basin

Particularly, the shale layer is often located at a few km or less from the surface of the earth, and is deposited at a thickness of several tens to several hundred meters. However, it is known that a layer having different characteristics is deposited in the shale layer depending on the form of the deposit. In other words, as the energy of seawater is lowered at the time of the watershed, fine grained grains are mainly moved and deposited to form a dense rock layer. On the other hand, as the seawater energy increases at the retraction stage, the grains of the silty grains migrate, A rock layer having a high fluid permeability can be formed, and the reserves of gas and oil may be different depending on the nature of the layer deposited at the time of the flooding and the retraction.

Therefore, it is possible to economically extract gas and oil from only a part of the thickness of the shale layer, and even though gas and oil can be extracted from other layers, economical efficiency is often low.

However, it is difficult to accurately identify the time of hatching and release, and it is difficult to determine the change of the sedimentation environment in the shale layer. Therefore, in order to economically produce gas and oil from the shale layer, it is necessary to determine the shale layer rich in organic matter and to accurately locate the borehole There is a difficulty. Therefore, the identification of the shale layer rich in organic matter and the determination of the horizontal drilling section should precede the characterization of the shale layer containing hydrocarbons.

Korean Patent No. 10-1416196B1 (June 27, 2014) Korean Registered Patent No. 10-1148835 (May 16, 2012)

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a method and system for collecting and analyzing physical logging data measured from a drilling core and a borehole, This paper proposes a method for predicting the economic development of the shale gas development zone based on the determination of the layer boundary boundary of the shale layer which can distinguish between the time of the hull and the time of the cancellation.

As a means for solving the above-mentioned problems, the present invention provides a method for measuring the total amount of gamma ray (GR) of physical logging data, the amount of spectral gamma ray (SGR) obtained from a drilling core and three elements of thorium (U), potassium (K) ratio (SGRR), acoustic impedance (AI) and total organic matter (TOC) Prediction method.

In one aspect of the present invention, a method for predicting a shale gas development zone through a layer boundary surface determination of a shale layer includes the steps of: (S1) analyzing a total gamma ray (GR) by depth in a borehole; (S2) analyzing the spectral gamma ray (SGR) of U, Th and K elements by depth in the drilling core; (S3) measuring and predicting the total organic carbon content (TOC) by depth in the drilling core; And (S4) calculating the acoustic impedance (AI) in the borehole.

In another embodiment of the present invention, the step (S2) may further include calculating a ratio (SGRR) of a spectral gamma ray of Th / U and Th / K, U / Th.

In another aspect of the present invention, it may comprise determining a time of the occlusion and retraction based on the one or more layer boundary surfaces determined through the steps.

According to another aspect of the present invention, the present invention provides a method of calculating a maximum value and a minimum value of a GR, and calculating a ratio of a section having a value lower than a first threshold ratio of a maximum value and a minimum value difference (ΔGR) Setting at least one first critical section in which a section having a plurality of sections each having a ratio of at least 80% is set; (S6) The maximum value and the minimum value of the TOC are calculated, and the ratio of the section having the value lower than the second threshold ratio of the maximum value to the minimum value difference (DELTA TOC) and the section having the high value are each 80% Setting at least one second critical interval; (S7) setting at least one third critical section having a value higher than the average value of the AI with respect to the total depth and having a locally maximum value; And (S8) comparing at least two thresholds selected from the first threshold section, the second threshold section and the third threshold section with respect to at least one of the first threshold section, the at least one second threshold section and the at least one third threshold section, And determining a common critical section in which the sections are common in the layer boundary plane.

In another embodiment of the present invention, the first threshold ratio may be 35% to 45%, and the second threshold ratio may be 15% to 25%.

In another aspect of the present invention, the step (S8) includes the steps of: determining a peak position of the SGRR in the common critical interval; Determining a point at which a common critical section coincides with at least one position selected from a position where Th / U is 10 or more and a position where Th / K is 40 or more, in comparison with a peak position of the common critical section and the SGRR; As shown in FIG.

In another aspect of the invention, the method may further comprise determining at least one sublayer boundary between at least one of the layer boundary interfaces and the adjacent layer boundary boundary, the sublayer boundary being present between the two layer boundary interfaces By comparing the increase / decrease trends with the local peak position of the SGRR and the depth of GR.

In another aspect of the present invention, the method may further include partitioning the height change trend of the sea level with reference to the detailed stratum boundary surface to determine the detail deformation and the timing of the deformation.

In another embodiment of the present invention, the borehole further comprises one or more boreholes formed in adjacent areas, and may further comprise determining a two-dimensional stratified boundary section from a plurality of same layer boundaries determined from the plurality of boreholes .

(SGRR), acoustical impedance (AI), total organic matter content (%) of the three elements (Th, K, U) TOC) can be determined and interpreted to determine the layer boundary boundary of the shale layer. By determining the layer boundary boundary, it is possible to accurately identify the shale layer containing a large amount of shale gas, Provides a method of predicting a development interval.

FIG. 1 is a view showing an application example of a sequential stratified analysis to which the method of the present invention is applied.
FIG. 2 is a view showing a two-dimensional cross-section where the same layer boundary surfaces determined through comparison with adjacent boreholes are connected to each other.
FIG. 3 is a schematic view showing characteristics of a sedimentation environment interpreted through a pattern change of a gamma ray logging layer or a natural potential logging layer data.

It will be apparent to those skilled in the art that the technical and scientific terms used herein may have other meanings as commonly understood by one of ordinary skill in the art to which the present invention belongs. Descriptions of the blurred notice function and configuration are omitted.

The "adjacent" layered interface in the present invention means a layered interface located immediately before or after any layered interface.

"Substrate interface" in the present invention means a stratified boundary located between a layered interface determined from a second-order TR sequence deposited for a relatively long period and from a third-order TR sequence deposited for a relatively short period of time, ≪ / RTI >

The sequential stratigraphic analysis is a technique used to analyze the distribution pattern of sedimentary layers. In order to infer the sedimentary environment of the sandstone or cover rocks acting as reservoir rocks and the shale layers acting as reservoir rocks in traditional resource exploration such as oil drilling Has been used as a basic tool in the field of geological structure technology.

However, unlike traditional resources, shale gas is contained in root cancer and is often located at a few kilometers or less from the surface of the earth. The sedimentary layers from which the gas and oil are produced from the shale layer are mudstone deposits rich in organic matter and the formation of the shale layer is the result of sedimentation of the sediments, , But it can be classified into a period in which the sea area is widened due to a rise in the sea level or a rise in the ground due to the relative sea level change and the change in the possible accumulation space. However, because of the characteristics of the shale layer being a reservoir rock and a source rock, it has been difficult to interpret the sedimentary layer composed of the same particles as the conventional sequential stratigraphic analysis method.

Generally, for the analysis of the stratum of the shale layer and the evaluation of the reservoir layer, methods such as physical logging analysis of shear core and borehole, shear stress analysis, rock analysis based on seismic wave measurement, and micro seismic wave irradiation have been used alone or in combination, Because of the characteristics of the shale layer, which is a rock and source rock, it has difficulties in the stratigraphic interpretation, so it is difficult to analyze the stratigraphy accurately and it is not easy to evaluate economically.

Physical logging data can be used for stratigraphic analysis, and natural gamma ray logging among physical logging data is used to measure the intensity of radiation naturally occurring in the stratum. Spectral gamma ray logging is a method of determining the elements constituting the ground layer by measuring the radiation spectrum generated in the ground layer. In the present invention, it has been found that the ratio of the amounts of the gamma rays of the three elements Th, U and K and the gamma ray of the three elements in the spectrum obtained from the spectral gamma ray logging layer is particularly effective in discriminating the layer boundary of the shale layer.

In one aspect of the present invention, a method for predicting a shale gas development zone through a layer boundary surface determination of a shale layer includes the steps of: (S1) analyzing a total gamma ray (GR) by depth in a borehole; (S2) analyzing the spectral gamma ray (SGR) of U, Th and K elements by depth in the drilling core; (S3) measuring and predicting the total organic carbon content (TOC) by depth in the drilling core; And (S4) calculating the acoustic impedance (AI) in the borehole.

The present invention can be utilized as a basic indicator for determining the layer by measuring the total gamma ray (GR) according to the depth. Sedimentary rocks or sedimentary metamorphic rocks including shale layers contain a large amount of radioactive isotopes as compared with other rocks such as igneous rocks and the total amount of gamma rays is changed because the contents of radioactive isotopes may be changed according to the change of the deposition environment . Therefore, the change in the total amount of gamma rays due to the depth can be effectively used to discriminate the stratum, and it is possible to accurately discriminate the stratum in combination with the various analytical methods described below.

The measurement of the total gamma ray (GR) can be determined by measuring the amount of gamma ray emitted from the borehole of a specific depth after irradiating the gamma ray to a specific depth borehole. The intensity of the total gamma ray (GR) It is preferable to use a gamma ray having the same energy for the entire depth of the borehole.

Further, the present invention can be utilized as a qualitative evaluation index for the analysis of the sedimentation environment and the stratification by measuring the total organic carbon content (TOC). In general, a section showing a high total organic carbon content can be judged to have been deposited at the time of flooding, while a section showing a low total organic carbon content can be judged to have been deposited at the time of a recession.

In the present invention, the total organic carbon content can be determined by pyrolysis analysis of drilled cores sampled according to drilling depth to determine the total organic carbon content at the corresponding depth. As a preferred embodiment, it is possible to grasp the trend of changes in the total organic carbon content from the drilled cores sampled according to depth, and to calculate the position of the stratified boundary more accurately by sampling more drilling cores at the points expected at the stratum boundary have.

Total organic carbon content can be quantified through sampled drilling cores, but it is possible to predict trends in total organic carbon content by depth by calculating two or more characteristics selected from gamma ray logging, density logging, resistivity logging and sonar logging . Since the rocky matter containing a large amount of organic matter exhibits low electrical conductivity compared with rocky rocks containing a small amount and at the same time the acoustic propagation velocity is also low, the resistivity value and the acoustic propagation velocity of the rocky rock are preferable indexes of the total organic carbon content . As a preferred method, there may be a method of combining the density and specific resistance of rocky rocks or the combination of density and acoustic propagation velocity of rocky rocks. Numerical methods are Schmoker method (1981), Meyer method (Meyer & Nederlof, 1984 (Fertl, & Chillingar, 1988), Passey (1990), and Gonzalez (2013) methods.

The section interpreted as a sediment sediment has a high total organic carbon content and a tendency to increase in spectral gamma ray value. However, the section interpreted as a shedding sediment has a low total organic carbon content and a high gamma ray value .

The present invention can be utilized as a secondary qualitative evaluation index for the analysis of the sedimentation environment and the stratification by means of the measured values of the acoustic impedance. The acoustic impedance can be defined as the product of the density of the rock and the acoustic velocity, and the acoustic impedance value has a different value depending on the characteristics of the rock quality.

Specifically, the sound wave logging can be calculated by measuring the time required for sending out the sound waves and returning the sound waves, and measuring the density of the rocky body through the density meter. Generally, the longer the deposition time of the rock layer is, the faster the sound transmission rate, and the shorter the deposition time, the slower the sound transmission rate. The transmission and measurement of sound waves can be measured through various means known in the art. It is generally known that it has a speed of 5000 ~ 6000 m / sec in the lower layer and 800 ~ 2000 m / sec in the upper layer with shorter deposition time.

As the sound transmission speed is higher, the acoustic resistance can be higher. The higher the density of the rock quality, the higher the sound propagation speed. Therefore, the sound wave logging obtained by measuring the time required for the sound waves to return can be used for quantitative Which can be a useful index to calculate. The calculated sound wave logarithm can have similar values within the error range in the same rock quality, but it can show a discontinuous change at the point where the rock quality changes, and this discontinuous change is crucial in distinguishing the stratigraphy of the sea- Indicators can be provided.

In the present invention, the three elements (Th, U, K) of the spectral gamma ray obtained from the drilling core can provide information on the deposition environment at the time of formation of the shale layer. Specifically, the high elemental content means that a large amount of influent or volcanic clusters of clastic sediments have occurred, and a high U elemental content may mean that sedimentation occurred in an organic-rich environment. In addition, high K element content means that sedimentation occurred in clay mineral environment. Kaolinite means growth environment, glauconite and pyrite means marine environment. It can mean.

In another embodiment of the present invention, the step (S2) may further include calculating a ratio (SGRR) of a spectral gamma ray of Th / U and Th / K, U / Th.

In one example of the present invention, it can be advantageously used to set the layer boundary surface by calculating the ratio of the spectral gamma ray of each element in the spectral gamma ray of the three elements (Th, U, K). Concretely, the section with high ratio of Th / U and Th / K means that large amount of clastic sediments were introduced, while the section with low ratio means that sedimentation occurred in the environment rich in organic matter.

The measurement of spectral gamma ray (SGR) can be determined by irradiating a spectral gamma ray to a drilling core and measuring the amount of gamma ray emitted from the drilling core. For the reasons described above, the quantities of thorium (Th), uranium ) And potassium (K) are measured in the spectral gamma ray (SGR) of the three elements. The spectral gamma ray (SGR) can use the same sensor as the total gamma ray (GR), and the results obtained from the sensor can be obtained by dividing the peak by each gamma ray energy through the multi-channel analyzer.

In a non-limiting example of the present invention, thorium may be 2.62 MeV, uranium (U) may be 1.76 MeV, potassium (K) may be 1.46 MeV, It is not limited to numbers.

In one example of the present invention, the change in the ratio of Th / U to Th / K can be preferably used for setting the main layer boundary as described below. After the stratified boundary setting, the sedimentation environment can be classified according to the tendency of the gamma ray by increasing up and decreasing up (FIG. 3).

In another aspect of the present invention, it may comprise determining a time of the occlusion and retraction based on the one or more layer boundary surfaces determined through the steps.

According to another aspect of the present invention, the present invention provides a method of calculating a maximum value and a minimum value of a GR, and calculating a ratio of a section having a value lower than a first threshold ratio of a maximum value and a minimum value difference (ΔGR) Setting at least one first critical section in which a section having a plurality of sections each having a ratio of at least 80% is set; (S6) The maximum value and the minimum value of the TOC are calculated, and the ratio of the section having the value lower than the second threshold ratio of the maximum value to the minimum value difference (DELTA TOC) and the section having the high value are each 80% Setting at least one second critical interval; (S7) setting at least one third critical section having a value higher than the average value of the AI with respect to the total depth and having a locally maximum value; And (S8) comparing at least two thresholds selected from the first threshold section, the second threshold section and the third threshold section with respect to at least one of the first threshold section, the at least one second threshold section and the at least one third threshold section, And determining a common critical section in which the sections are common in the layer boundary plane.

GR, SGRR, TOC and AI can show different characteristics depending on the depth depending on the characteristics of rock quality. As described above, the total gamma ray (GR) can be effectively used to discriminate stratigraphy because it shows the content of radioactive isotopes in accordance with the change of the deposition environment, and the total organic carbon content (TOC) In addition to providing qualitative information about the shale gas, it can provide direct information on the location of the shale gas, and acoustic impedance can provide qualitative information on the quality of rock masses as well as discontinuous changes Can provide a crucial indicator for distinguishing the stratigraphy of sedimentation and sedimentation.

Specifically, since the GR and TOC provide qualitative information on the damage and retraction deposits, after calculating the difference between the maximum value and the minimum value (GR) of the GR at the total depth, the ratio of the interval having a value lower than the first threshold ratio And a ratio of a period having a high value of 80% or more may be set.

Likewise, the TOC can also set one or more second critical intervals where the ratio of the interval having the value lower than the second threshold ratio of the maximum value and the minimum value difference (DELTA TOC) and the interval of the interval having the high value meet each 80% have. On the other hand, at least one third critical section having a value higher than the average value of the AI with respect to the total depth and having a locally maximum value can be set.

When the first to third critical sections are set, a common critical section in which two or more critical sections are common to each other can be determined as the stratum boundary. As the error in measurement and analysis is small, The section may be located closer to the same area.

Preferably, a point at which the third critical section appears in a section where the first critical section overlaps with the second critical section may be determined as the layer boundary, and the layer boundary may represent a more accurate point. However, It is not.

In another embodiment of the present invention, the first threshold ratio may be 35% to 45%, and the second threshold ratio may be 15% to 25%. More preferably, the first threshold ratio may be between 38% and 42%, and the second threshold ratio may be between 18% and 22%.

In another aspect of the present invention, the step (S8) includes the steps of: determining a peak position of the SGRR in the common critical interval; Determining a point at which a common critical section coincides with at least one position selected from a position where Th / U is 10 or more and a position where Th / K is 40 or more, in comparison with a peak position of the common critical section and the SGRR; As shown in FIG.

As mentioned above, a section with a high ratio of Th / U to Th / K means that a large amount of clastic sediments (cultivated sediments) have been introduced. Conversely, a section with a low ratio means that sedimentation occurred in an environment rich in organic matter Therefore, when the Th / U and Th / K ratios of the spectral gamma ray are shown, it is possible to provide a decisive index for setting the main stratum boundary surface through a plurality of peaks appearing in the SGRR.

Preferably, it may be at least one position selected from a position where Th / U of SGRR is 10 or more and a position where Th / K is 45 or more, and a point where the common critical section coincides with SGRR of Th / Layer boundary, but the present invention is not limited thereto.

If a peak of the SGRR is located in a critical section in which two or more critical sections selected from the first critical section, the second critical section, and the third critical section are commonly present, the corresponding point may be determined as the layer boundary. When the stratum boundary plane is determined, a second order T-R sequence (second order Transgressive-Regressive sequence) can be determined first, and the time of deterioration and the time of retraction can be determined therefrom.

In another aspect of the present invention, a second order TRS (Second Order Transgressive-Regressive sequence) may be determined when a layer boundary boundary is determined, and one or more detailed layer boundary surfaces between one or more arbitrary layer boundary surfaces and an adjacent layer boundary surface And the detail layer boundary surface may be determined by comparing the increase / decrease trends with the depth of the GR and the local peak position of the SGRR existing between the two layer boundary interfaces.

In the present invention, the setting of the detailed stratum boundary surface may be determined by repeating the steps as described above, and the threshold ratio of the physical logging data and the value of the SGRR of Th / U and Th / It may be necessary to adjust it according to the variation range. Specifically, the SGRR for the detailed layer boundary determination may have a small value relative to the SGRR used for the layer boundary determination, and the ratio may be a ratio of 0.5 to 0.8 of the SGRR used for the layer boundary determination.

Once the detailed stratum boundary is determined, it is possible to determine the 3rd order transgressive-regressive sequence. From this, it can be decided to segment the trend of the sea level height change during the time of the overtreatment and the retreat, and the stratum boundary and detail stratum boundary After the determination, the deposition environment can be classified according to the tendency of the gamma ray to increase upwards and upwards (decrease up).

Specifically, the increase in the total gamma ray (GR) in the trend of change in the total gamma ray (GR) may mean that the ratio of the shale layer increases, so that the direction in which the total gamma ray (GR) And the direction in which the total gamma ray (GR) decreases in the direction of the ground surface can be determined by upward assembly.

The second TR sequence may be a basic section for a period of one million to ten million years, and the third TR sequence may be a basic section for a period of 100,000 to 1,000,000 years. However, It is not limited to the above period because it can be changed according to the change of the deposition environment.

In another embodiment of the present invention, the borehole further includes a plurality of boreholes formed in adjacent areas, and a two-dimensional cross section of the same layer boundary determined from TGR, SGR, SGRR, TOC and AI calculated from a plurality of boreholes And < / RTI >

In one embodiment of the present invention, the borehole may be a plurality of boreholes formed in the adjacent area, and may be a spectral gamma ray (SGR) of the total gamma ray (GR), U, Th and K elements calculated from a plurality of boreholes, The layered boundary of the shale layer can be determined through the total organic carbon content (TOC) and the acoustic impedance (AI), and the thickness of the sediment body and the direction of sediment entry are preferably calculated by connecting the same layer boundary surfaces determined in a plurality of boreholes .

The distance between the boreholes is known in the art or may be selected by the ordinary skilled artisan for the development area of the shale gas and may be determined depending on the area for horizontal drilling, but is not limited thereto.

In the case where the time of the flooding and the retraction is determined according to the steps and the method described above, and the sedimentation environment of the upward granulation and the upward granulation is classified, a shale layer containing a large amount of shale gas is detected, A prediction method can be provided.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples. However, the present invention is described in more detail with reference to the following Examples. However, the scope of the present invention is not limited by the following Examples.

[Example 1]

 The spectral gamma ray (SGR), total organic carbon content (TOC) of the total gamma ray (GR), U, Th and K elements in the borehole in the Devonian shales located in the northeast of Canada, And acoustic impedance (AI) were measured according to depth. In addition, the SGRR of Th / U, Th / K is calculated and shown, and the results are shown in FIG.

The second TR sequence is set based on the position where Th / U is 10 or more and the position where Th / K is 40 or more. The third TR sequence is set based on a position where Th / U is 8 or more and a point where Th / K is 20 or more Respectively.

Considering that the point where the value of Th / K is 40 or more may be the boundary of the stratum, confirm whether the AI value is in the interval of change or not, and check whether the change of the TOC value is the increase or decrease. Respectively.

The determination of the sea bed sediment body (TST) and the retraction sediment body (RST) after the stratified boundary surface setting was determined with reference to Fig.

[Example 2]

The spectral gamma ray (SGR), total organic carbon content (TOC) and acoustic impedance (AI) of the total gamma ray (GR), U, Th and K elements in the borehole were measured depth by depth from three boreholes Was carried out in the same manner as in Example 1.

As a result of connecting the same layer boundary surfaces determined by a plurality of boreholes, a two-dimensional cross-section could be determined as shown in Fig. 2, and the thickness of sediment bodies and the direction of sediment ingress could be calculated

As the thickness of the deposited body and the direction of entry are determined, the development zone of the shale gas and the preferred zone for horizontal drilling can be determined.

Claims (10)

(S1) analyzing the total gamma ray (GR) by depth in the borehole;
(S2) analyzing the spectral gamma ray (SGR) of U, Th and K elements by depth in the drilling core;
(S3) measuring and predicting the total organic carbon content (TOC) by depth in the drilling core; And
(S4) calculating the acoustic impedance (AI) in the borehole; and predicting the shale gas development zone through the determination of the layer boundary of the shale layer The method according to claim 1,
The step (S2) may further include calculating a ratio (SGRR) of the spectral gamma ray of Th / U and Th / K to the shale gas development interval prediction method The method according to claim 1,
And determining the time of the dehydration and the deactivation based on the at least one stratum boundary surface. The method according to claim 1,
(S5) The maximum value and the minimum value of the GR are calculated, and the ratio of the interval having the value lower than the first threshold ratio of the maximum value and the minimum value difference (DELTA GR) and the interval having the high value is 80% Setting at least one first critical interval;
(S6) The maximum value and the minimum value of the TOC are calculated, and the ratio of the section having the value lower than the second threshold ratio of the maximum value to the minimum value difference (DELTA TOC) and the section having the high value are each 80% Setting at least one second critical interval;
(S7) setting at least one third critical section having a value higher than the average value of the AI with respect to the total depth and having a locally maximum value; And
(S8) comparing the at least one first threshold section, the at least one second threshold section, and the at least one third threshold section with each other to determine at least one of the first threshold section, the second threshold section and the third threshold section, And a step of determining a common critical section common to the shale gas development section as a stratum boundary surface. 5. The method of claim 4,
Wherein the first threshold ratio is 35% to 45%, and the second threshold ratio is 15% to 25%. 5. The method of claim 4,
Wherein the step (S8) comprises: determining a peak position of the SGRR in the common critical interval; And
Determining a point at which a common critical section coincides with at least one position selected from a position where Th / U is greater than or equal to 10 and a position where Th / K is greater than or equal to 40 in comparison with a peak position of the common critical section and the SGRR; A shale gas development section prediction method 5. The method of claim 4,
Further comprising the step of determining one or more detailed stratum boundary surfaces between any stratum boundary surfaces and adjacent stratum boundary surfaces, 8. The method of claim 7,
Wherein the detailed stratified boundary surface is determined by comparing the increase / decrease trends according to the local peak position of SGRR and the depth of GR existing between the two stratum boundary surfaces. 8. The method of claim 7,
Wherein the shade gas development section prediction method is characterized by dividing the height change trend of the sea level on the basis of the detailed stratification boundary surface to determine the detail deformation and the release timing 11. The method according to any one of claims 1 to 10, wherein the borehole further comprises at least one borehole formed in an adjacent area, wherein determining a two-dimensional stratified boundary section from a plurality of same layer boundaries determined from the plurality of boreholes Characteristics of Shale gas development section prediction method

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