Lithology identification method of continental liquid hydrocarbon shale layer based on elements

Abstract

The present invention relates to the technical field of lithology identification methods, and is a method for identifying the lithology of continental liquid hydrocarbon shale layers based on elements, including establishing a radar chart using the element content of the continental liquid hydrocarbon shale layer rock sample of the known lithology, obtaining three element combinations with relatively high contents through the radar chart; converting the three element combinations with relatively high contents using an element conversion model to obtain the conversion percentage of the elements; establishing a lithology identification triangle chart using the conversion percentage of the elements combined with the lithology of the continental liquid hydrocarbon shale layer rock sample of the known lithology; and identifying the lithology of the continental liquid hydrocarbon shale layer rock sample of the unknown lithology. The lithology identification triangle chart of the present invention has a more detailed lithology division, solves the problem of the difficulty in identifying and distinguishing the lithology of the existing continental liquid hydrocarbon shale layer, improves the lithology identification rate and accuracy of the continental liquid hydrocarbon shale layer, and provides a technical guarantee for unconventional oil and gas exploration and development.

Description

Technical Field

[0001] The invention relates to the technical field of lithology identification methods, and is a method for identifying the lithology of continental liquid hydrocarbon shale layers based on elements. Background Art

[0002] In recent years, the exploration and development of unconventional oil and gas and geological research have been continuously strengthened. Various types of unconventional oil and gas resources such as shale oil, shale oil and gas, and coalbed methane have occupied an increasingly large proportion in my country's energy structure. Among them, the offshore saline lake basin mixed rock deposits are one of the oldest terrestrial liquid hydrocarbon shale formations in China, and the Jimusar shale oil in the Junggar Basin belongs to the offshore saline lake basin mixed rock deposits. There are two major difficulties in the exploration and development process: First, the oil-bearing layers are thin interlayers in the vertical direction, with complex and diverse lithology and mineral composition. They are mostly transitional rocks of clastic sedimentation and chemical sedimentation, which are difficult to identify and distinguish; second, the reservoir lithology changes rapidly and the regional characteristics are poor. Summary of the invention

[0003] The present invention provides a method for identifying the lithology of continental liquid hydrocarbon shale layers based on elements, which overcomes the shortcomings of the above-mentioned prior art and can effectively solve the problem that the existing lithology identification method is not suitable for lithology identification of continental liquid hydrocarbon shale layers.

[0004] The technical solution of the present invention is achieved by the following measures: a method for identifying the lithology of continental liquid hydrocarbon shale layers based on elements, comprising:

[0005] Step 1, obtaining the element contents of a plurality of continental liquid hydrocarbon shale layer samples of known lithology;

[0006] Step 2, using the element contents of the continental liquid hydrocarbon shale layer samples of known lithology to establish a radar map, and obtaining the three element combinations with relatively high contents in each continental liquid hydrocarbon shale layer sample of known lithology through the radar map;

[0007] Step 3, converting the three elements with relatively high contents into conversion percentages using an element conversion model;

[0008] Step 4, using the conversion percentage of the element in combination with the lithology of the continental liquid hydrocarbon shale layer rock sample of known lithology, to establish a lithology identification triangle chart;

[0009] Step 5, identifying the lithology of the continental liquid hydrocarbon shale layer sample of unknown lithology through the lithology identification triangle plate.

[0010] The element content of the rock sample can be obtained using an element analyzer.

[0011] The following are further optimizations and / or improvements to the above technical solutions:

[0012] In the above step 2, the combination of three elements with relatively high contents includes three elements of Si, Al, Ca, Mg and Fe.

[0013] In the above step 3, the three elements with relatively high contents are combined and converted using an element conversion model to obtain conversion percentages of two elements, as follows:

[0014] The three elements with relatively high contents are A, B and C. The three elements A, B and C are Si, Al, Ca, Mg and Fe. The element conversion model formula is as follows:

[0015]

[0016] A Z Represents the relative number of A elements; B Z Represents the relative number of element B; C Z Represents the relative number of C element; C A Represents the percentage of element A,%; C B Represents the percentage of element B,%; C C represents the percentage of element C; M represents the relative conversion number of element A; N represents the relative conversion number of element B.

[0017] In the above step 4, the conversion percentage of the element is combined with the lithology of the continental liquid hydrocarbon shale layer sample of the known lithology to establish a lithology identification triangle map, as follows:

[0018] Along the clockwise direction, the lithology identification triangle is drawn with element A as the right endpoint of the lithology identification triangle, element B as the left endpoint of the lithology identification triangle, element C as the upper endpoint of the lithology identification triangle, M as the x-coordinate, and N as the y-coordinate.

[0019] In the above step 5, the lithology of the continental liquid hydrocarbon shale layer rock sample of unknown lithology is identified through the lithology identification triangle plate, specifically:

[0020] For a continental liquid hydrocarbon shale layer sample of unknown lithology, execute steps 1 to 3 to obtain the conversion percentage of the element. When executing steps 1 to 3 to obtain the conversion percentage of the element, the continental liquid hydrocarbon shale layer sample of known lithology is replaced with the continental liquid hydrocarbon shale layer sample of unknown lithology. When the coordinates composed of the conversion percentages M and N fall into a certain lithology area in the lithology identification triangle map composed of the same elements, the lithology of the continental liquid hydrocarbon shale layer sample of unknown lithology is identified; otherwise, it cannot be identified.

[0021] Preferably, the lithology identification triangle plate includes a lithology identification triangle plate for Si, Al and Fe elements, a lithology identification triangle plate for Si, Ca and Mg elements, and a lithology identification triangle plate for Si, Al and Ca elements; in the lithology identification triangle plate for Si, Al and Fe elements, along the clockwise direction, the Si element is the right endpoint of the lithology identification triangle plate, the Fe element is the left endpoint of the lithology identification triangle plate, and the Al element is the upper endpoint of the lithology identification triangle plate; in the lithology identification triangle plate for Si, Ca and Mg elements, along the clockwise direction, the Si element is the right endpoint of the lithology identification triangle plate, the Mg element is the left endpoint of the lithology identification triangle plate, and the Ca element is the upper endpoint of the lithology identification triangle plate; in the lithology identification triangle plate for Si, Al and Ca elements, along the clockwise direction, the Al element is the right endpoint of the lithology identification triangle plate, the Ca element is the left endpoint of the lithology identification triangle plate, and the Si element is the upper endpoint of the lithology identification triangle plate.

[0022] Preferably, the lithology identification triangle chart of Si, Al and Fe elements is used to identify mudstone, fine sandstone and siltstone in the Jimsar shale oil block in the Junggar Basin; the lithology identification triangle chart of Si, Ca and Mg elements is used to identify dolomitic mudstone, mudstone and lime-bearing mudstone in the Jimsar shale oil block in the Junggar Basin; the lithology identification triangle chart of Si, Al and Ca elements is used to identify lime mudstone, dolomitic mudstone, fine sandstone and lime-bearing fine sandstone in the Jimsar shale oil block in the Junggar Basin.

[0023] The present invention establishes a rock mineral characteristic map (i.e., a lithology identification triangle map) classified by mineral element composition based on the different mineral element compositions contained in different rocks. Compared with the existing lithology identification method, the lithology identification triangle map of the present invention has a more detailed lithology classification and can be applied to the lithology identification of continental liquid hydrocarbon shale layers, especially the lithology identification of continental liquid hydrocarbon shale layers in the Jimusar shale oil block of the Junggar Basin. It solves the problem of the difficulty in distinguishing the lithology of the existing continental liquid hydrocarbon shale layers, improves the lithology identification rate and accuracy of the continental liquid hydrocarbon shale layers, and provides technical guarantee for unconventional oil and gas exploration and development. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Attached Figure 1 This is a radar chart of the element content of a certain mudstone.

[0025] Attached Figure 2 This is a radar chart of the element content of a certain sandstone.

[0026] Attached Figure 3 This is a radar chart of the element content of a certain gray mudstone.

[0027] Attached Figure 4 This is a lithological plate showing the Si, Al and Fe element contents.

[0028] Attached Figure 5 This is a lithological plate showing the content of Fe, Mg, K and Na elements.

[0029] Attached Figure 6 This is the lithology identification triangle chart for Si, Al and Fe elements.

[0030] Attached Figure 7 This is the triangular plate for lithology identification of Si, Ca and Mg elements.

[0031] Attached Figure 8 This is the triangular plate for lithology identification of Si, Al and Ca elements.

[0032] Attached Fig. 9 This is the comprehensive evaluation diagram of well element logging for Well LX. DETAILED DESCRIPTION

[0033] The present invention is not limited by the following embodiments, and specific implementation methods can be determined according to the technical solution of the present invention and actual conditions. The percentages in the present invention, unless otherwise specified, are all mass percentages.

[0034] The present invention will be further described below in conjunction with embodiments:

[0035] Example 1: A method for identifying the lithology of continental liquid hydrocarbon shale layers based on elements, comprising:

[0036] Step 1: Obtain the element content of a continental liquid hydrocarbon shale layer sample of known lithology.

[0037] Step 2: establishing a radar map using the element contents of the continental liquid hydrocarbon shale layer samples of known lithology, and obtaining the three element combinations with relatively high contents in each continental liquid hydrocarbon shale layer sample of known lithology through the radar map.

[0038] The main rock types of continental liquid hydrocarbon shale layers include mudstone and sandstone. Mudstone includes pure mudstone, lime-bearing mudstone, lime mudstone, cloud-bearing mudstone, silty mudstone, etc. Sandstone includes fine sandstone, lime-bearing fine sandstone, etc. The main components of rocks are Si, Al, Ca, Mg, Fe, K and other elements.

[0039] Here is an example to illustrate the process of drawing a radar chart:

[0040] The following are radar charts of a mudstone, a sandstone, and a gray mudstone. The radar charts are drawn with five elements with relatively high contents, as follows:

[0041] (1) Radar chart of element content in a certain mudstone Figure 1 .

[0042] pass Figure 1 It can be seen that mudstone is characterized by high Si, Al, and Fe elements.

[0043] (2) Radar chart of element content in a sandstone Figure 2 .

[0044] pass Figure 2 It can be seen that sandstone is characterized by high Si, Fe and Al elements.

[0045] (3) Radar chart of element content of a certain ash mudstone Figure 3 .pass Figure 3 It can be seen that the characteristics of limy mudstone are high Si, Ca, Fe and Mg elements.

[0046] Step 3: convert the three elements with relatively high contents into conversion percentages using an element conversion model.

[0047] Step 4: Using the conversion percentage of the element in combination with the lithology of the continental liquid hydrocarbon shale layer rock sample of known lithology, a lithology identification triangle chart is established.

[0048] Step 5, identifying the lithology of the continental liquid hydrocarbon shale layer sample of unknown lithology through the lithology identification triangle plate.

[0049] Generally speaking, there are the following methods for identifying the lithology of continental liquid hydrocarbon shale layers: using the content of Fe, Mg, K, and Na as a lithology chart, or using the content of Si, Al, and Fe as a lithology chart, such as Figures 4 to 5 As shown by Figures 4 to 5 It can be seen that these two types of plates can only distinguish sandstone and mudstone, and the lithology division is relatively rough.

[0050] Embodiment 2: As an optimization of the above embodiment, in step 2, the combination of three elements with relatively high contents is selected from three elements of Si, Al, Ca, Mg and Fe.

[0051] Embodiment 3: As an optimization of the above embodiment, in step 3, the three elements with relatively high contents are combined and converted using an element conversion model to obtain conversion percentages of two elements, as follows:

[0052] The three elements with relatively high contents are composed of three elements A, B and C, and the three elements A, B and C are selected from three elements of Si, Al, Ca, Mg and Fe. The element conversion model formula is as follows:

[0053]

[0054] A Z Represents the relative number of A elements; B Z Represents the relative number of element B; C Z Represents the relative number of C element; C ARepresents the percentage of element A,%; C B Represents the percentage of element B,%; C C represents the percentage of element C; M represents the relative conversion number of element A; N represents the relative conversion number of element B.

[0055] Example 4: As an optimization of the above Example 3, in step 4, the conversion percentage of the element is combined with the lithology of the continental liquid hydrocarbon shale layer sample of the known lithology to establish a lithology identification triangle map, as follows:

[0056] Along the clockwise direction, the lithology identification triangle is drawn with element A as the right endpoint of the lithology identification triangle, element B as the left endpoint of the lithology identification triangle, element C as the upper endpoint of the lithology identification triangle, M as the x-coordinate, and N as the y-coordinate.

[0057] Example 5: As an optimization of the above example, in step 5, the lithology of the continental liquid hydrocarbon shale layer rock sample of unknown lithology is identified through the lithology identification triangle plate, specifically:

[0058] For a continental liquid hydrocarbon shale layer sample of unknown lithology, execute steps 1 to 3 to obtain the conversion percentage of the element. When executing steps 1 to 3 to obtain the conversion percentage of the element, the continental liquid hydrocarbon shale layer sample of known lithology is replaced with the continental liquid hydrocarbon shale layer sample of unknown lithology. When the coordinates composed of the conversion percentages M and N fall into a certain lithology area in the lithology identification triangle map composed of the same elements, the lithology of the continental liquid hydrocarbon shale layer sample of unknown lithology is identified; otherwise, it cannot be identified.

[0059] Example 6: As an optimization of the above-mentioned Example 5, the lithology identification triangle chart includes a lithology identification triangle chart of Si, Al and Fe elements, a lithology identification triangle chart of Si, Ca and Mg elements, and a lithology identification triangle chart of Si, Al and Ca elements; in the lithology identification triangle chart of Si, Al and Fe elements, along the clockwise direction, the Si element is the right end point of the lithology identification triangle chart, the Fe element is the left end point of the lithology identification triangle chart, and the Al element is the upper end point of the lithology identification triangle chart ; In the lithology identification triangle chart of Si, Ca and Mg elements, along the clockwise direction, the Si element is the right endpoint of the lithology identification triangle chart, the Mg element is the left endpoint of the lithology identification triangle chart, and the Ca element is the upper endpoint of the lithology identification triangle chart; in the lithology identification triangle chart of Si, Al and Ca elements, along the clockwise direction, the Al element is the right endpoint of the lithology identification triangle chart, the Ca element is the left endpoint of the lithology identification triangle chart, and the Si element is the upper endpoint of the lithology identification triangle chart.

[0060] Example 7: As an optimization of the above Example 6, the lithology identification triangle chart of Si, Al and Fe elements is used to identify mudstone, fine sandstone and siltstone ( Figure 6 ); The lithology identification triangle chart of Si, Ca and Mg elements is used to identify dolomitic mudstone, mudstone and lime-bearing mudstone in the Jimusar shale oil block of the Junggar Basin ( Figure 7 ); The lithology identification triangle chart of Si, Al and Ca elements is used to identify the lime mudstone, cloud-bearing mudstone, fine sandstone and lime-bearing fine sandstone in the Jimusar shale oil block of the Junggar Basin ( Figure 8 ).

[0061] The following uses fine sandstone as an example to illustrate the process of establishing the lithology identification triangle chart of Si, Al and Ca elements.

[0062] Table 1 shows some data of Al, Ca, Si, K elements and gamma GR values ​​of a continental liquid hydrocarbon shale layer sample (from the Jimusar shale oil block in the Junggar Basin) with fine sandstone lithology.

[0063] Through the radar chart, a triangular chart was established based on the contents of the three elements Al, Ca and Si.

[0064] The relative number A of Al element is calculated by the element conversion model formula described in Example 3. Z 、The relative number of Ca element B Z 、The relative number of Si element C Z , the relative conversion number M of Al element, and the relative conversion number N of Ca element (see Table 2).

[0065] In the clockwise direction, the lithology identification triangle is drawn with Al as the right end point of the lithology identification triangle, Ca as the left end point of the lithology identification triangle, Si as the upper end point of the lithology identification triangle, M as the x coordinate, and N as the y coordinate, to obtain Figure 8 Fine sandstone area shown.

[0066] Example 8: A method for identifying the lithology of continental liquid hydrocarbon shale layers based on elements, comprising:

[0067] Step 1, obtaining the element contents of a plurality of continental liquid hydrocarbon shale layer samples of known lithology;

[0068] Step 2, using the element contents of the continental liquid hydrocarbon shale layer samples of known lithology to establish a radar map, and obtaining the three element combinations with relatively high contents in each continental liquid hydrocarbon shale layer sample of known lithology through the radar map;

[0069] A combination of three elements with relatively high contents, selected from three of Si, Al, Ca, Mg and Fe elements.

[0070] Step 3, converting the three elements with relatively high contents into the conversion percentage of the elements using the element conversion model, as follows:

[0071] The three elements with relatively high contents are composed of three elements A, B and C, and the three elements A, B and C are selected from three elements of Si, Al, Ca, Mg and Fe. The element conversion model formula is as follows:

[0072]

[0073] A Z Represents the relative number of A elements; B Z Represents the relative number of element B; C Z Represents the relative number of C element; C A Represents the percentage of element A,%; C B Represents the percentage of element B,%; C C represents the percentage of element C; M represents the relative conversion number of element A; N represents the relative conversion number of element B.

[0074] Step 4, using the conversion percentage of the element combined with the lithology of the continental liquid hydrocarbon shale layer sample of known lithology, to establish a lithology identification triangle chart; the details are as follows:

[0075] Along the clockwise direction, the lithology identification triangle is drawn with element A as the right endpoint of the lithology identification triangle, element B as the left endpoint of the lithology identification triangle, element C as the upper endpoint of the lithology identification triangle, M as the x-coordinate, and N as the y-coordinate.

[0076] Step 5, identifying the lithology of the continental liquid hydrocarbon shale layer sample of unknown lithology through the lithology identification triangle plate, specifically:

[0077] For a continental liquid hydrocarbon shale layer sample of unknown lithology, execute steps 1 to 3 to obtain the conversion percentage of the element. When executing steps 1 to 3 to obtain the conversion percentage of the element, the continental liquid hydrocarbon shale layer sample of known lithology is replaced by the continental liquid hydrocarbon shale layer sample of unknown lithology. When the coordinates composed of M and N fall into a certain lithology area in the lithology identification triangle map composed of the same elements, the lithology of the continental liquid hydrocarbon shale layer sample of unknown lithology is identified; otherwise, it cannot be identified.

[0078] When identifying the lithology of a continental liquid hydrocarbon shale layer rock sample of unknown lithology, only one rock sample is required for the continental liquid hydrocarbon shale layer rock sample of unknown lithology.

[0079] Example 9: The method described in Example 8 was used to identify the lithology of a continental liquid hydrocarbon shale layer sample. The sample (hereinafter referred to as sample 1) was taken from the LX well at a depth of 2,900 meters. The element content of sample 1 was analyzed by an element analyzer. The main element contents of sample 1 were: Si: 25.1%, Al: 2.7%, Ca: 6.7%, and Mg: 2.8%.

[0080] Here, three elements Si, Mg and Ca are selected, Si is the A element, Mg is the B element, and Ca is the C element. Step 5 of the method described in Example 8 is performed to calculate:

[0081] A Z =72.54

[0082] B Z =8.1

[0083] C Z =19.36

[0084] M=76.54

[0085] N=8.1

[0086] The coordinates formed by M and N are put into the lithology identification triangle chart of Si, Mg and Ca elements ( Figure 7 ), the coordinates coincide with the lime mudstone area, so the lithology of rock sample 1 is lime mudstone. The lithology identification result of Example 9 of the present invention is compared with the well element logging comprehensive evaluation diagram of the LX well. The well element logging comprehensive evaluation diagram of the LX well ( Fig. 9 ) shows that the lithology at 2900 meters is lime-bearing mudstone, which means that the lithology identification result of Example 9 is consistent with the logging interpretation result. It can be seen that the lithology identification method of continental liquid hydrocarbon shale layer based on elements of the present invention is suitable for the lithology identification of continental liquid hydrocarbon shale layer.

[0087] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

[0088] Table 1

[0089] .

[0090] Table 2

[0091] .

Claims

1. A method for identifying the lithology of continental liquid hydrocarbon shale layers based on elements, characterized in that include: Step 1, obtaining the element contents of a plurality of continental liquid hydrocarbon shale layer samples of known lithology; Step 2, using the element contents of the continental liquid hydrocarbon shale layer samples of known lithology to establish a radar map, and obtaining the three element combinations with relatively high contents in each continental liquid hydrocarbon shale layer sample of known lithology through the radar map; Step 3, converting the three elements with relatively high contents into conversion percentages using an element conversion model; Step 4, using the conversion percentage of the element in combination with the lithology of the continental liquid hydrocarbon shale layer rock sample of known lithology, to establish a lithology identification triangle chart; Step 5, identifying the lithology of the continental liquid hydrocarbon shale layer sample of unknown lithology through the lithology identification triangle plate; Wherein, in step 2, the combination of three elements with relatively high contents is selected from three elements of Si, Al, Ca, Mg and Fe; In step 3, the three elements with relatively high contents are combined and converted using an element conversion model to obtain conversion percentages of two elements, as follows: The three elements with relatively high contents are composed of A, B and C. The three elements A, B and C are selected from three of Si, Al, Ca, Mg and Fe. The element conversion model formula is as follows: A Z Represents the relative number of A elements; B Z Represents the relative number of element B; C Z Represents the relative number of C element; C A Represents the percentage of element A,%; C B Represents the percentage of element B,%; C C represents the percentage of element C,%; M represents the relative conversion number of element A; N represents the relative conversion number of element B; In step 4, the conversion percentage of the element is combined with the lithology of the continental liquid hydrocarbon shale layer sample of the known lithology to establish a lithology identification triangle map, as follows: Along the clockwise direction, the lithology identification triangle is drawn with element A as the right end point of the lithology identification triangle, element B as the left end point of the lithology identification triangle, element C as the upper end point of the lithology identification triangle, M as the x coordinate, and N as the y coordinate; In step 5, the lithology of the continental liquid hydrocarbon shale layer rock sample of unknown lithology is identified through the lithology identification triangle plate, specifically: For a continental liquid hydrocarbon shale layer sample of unknown lithology, execute steps 1 to 3 to obtain the conversion percentage of the element. When executing steps 1 to 3 to obtain the conversion percentage of the element, the continental liquid hydrocarbon shale layer sample of known lithology is replaced with the continental liquid hydrocarbon shale layer sample of unknown lithology. When the coordinates composed of the conversion percentages M and N fall into a certain lithology area in the lithology identification triangle map composed of the same elements, the lithology of the continental liquid hydrocarbon shale layer sample of unknown lithology is identified; otherwise, it cannot be identified.

2. The method for identifying lithology of continental liquid hydrocarbon shale layers based on elements according to claim 1, characterized in that The lithology identification triangle chart includes the lithology identification triangle chart of Si, Al and Fe elements, the lithology identification triangle chart of Si, Ca and Mg elements, and the lithology identification triangle chart of Si, Al and Ca elements; in the lithology identification triangle chart of Si, Al and Fe elements, along the clockwise direction, the Si element is the right end point of the lithology identification triangle chart, the Fe element is the left end point of the lithology identification triangle chart, and the Al element is the upper end point of the lithology identification triangle chart; in the lithology identification triangle chart of Si, Ca and Mg elements, along the clockwise direction, the Si element is the right end point of the lithology identification triangle chart, the Mg element is the left end point of the lithology identification triangle chart, and the Ca element is the upper end point of the lithology identification triangle chart; in the lithology identification triangle chart of Si, Al and Ca elements, along the clockwise direction, the Al element is the right end point of the lithology identification triangle chart, the Ca element is the left end point of the lithology identification triangle chart, and the Si element is the upper end point of the lithology identification triangle chart.

3. The method for identifying lithology of continental liquid hydrocarbon shale layers based on elements according to claim 2, characterized in that The lithology identification triangle chart of Si, Al and Fe elements is used to identify mudstone, fine sandstone and siltstone in the Jimusar shale oil block in the Junggar Basin.

4. The method for identifying lithology of continental liquid hydrocarbon shale layers based on elements according to claim 2 or 3, characterized in that The lithology identification triangle chart of Si, Ca and Mg elements is used to identify dolomitic mudstone, mudstone and lime-bearing mudstone in the Jimusar shale oil block in the Junggar Basin; the lithology identification triangle chart of Si, Al and Ca elements is used to identify lime mudstone, dolomitic mudstone, fine sandstone and lime-bearing fine sandstone in the Jimusar shale oil block in the Junggar Basin.

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