A method and device for combined graptolite and electrical property curve stratigraphic division

Abstract

The present application relates to a kind of inkstone and electrical curve combined stratum division method and device, method includes taking core well as standard well, obtains the natural gamma logging curve of standard well;Shale inkstone of standard well is identified to genus and species, obtains inkstone sublayer;According to the sedimentary environment where standard well is located, area classification is carried out;The corresponding relationship of inkstone sublayer of standard well and the natural gamma logging curve of standard well is established, the position of each inkstone zone is confirmed;Natural gamma logging curve is collected from new well, and the natural gamma logging curve of new well is obtained;According to the sedimentary environment of the area where new well is located, from the corresponding area classification, the corresponding standard well natural gamma logging curve is matched, and the corresponding inkstone sublayer is used as the inkstone sublayer of the new well.As compared with prior art, the present application does not need to carry out drilling coring to new well, can realize the rapid division to the high-yield section of shale gas enrichment, improves the prediction accuracy of shale gas horizontal well target area.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of stratum division, and particularly relates to a graptolite and electrical curve combined stratum division method and device. BACKGROUND

[0002] Shale is a kind of fine-grained sediment, and the mineral particles in general rock are less than 0.0625mm. Shale is formed in a relatively stable still water environment, and the color is generally dark gray to black. Shale is generally a low-porosity and low-permeability reservoir. The connectivity of shale is a key parameter for shale gas geological evaluation. The reservoir with good connectivity generally has high permeability, and the shale gas well has high production. Conversely, the shale gas well has low production. Shale can be divided into low-maturity (Ro<0.8%), medium-maturity (0.8%<Ro<2.5%) and high-maturity shale (Ro>2.5%) due to different evolution degrees.

[0003] In the study of biological fossils in the Wufeng-Luomaxi shale, the graptolite is a globally recognized dominant class, which provides the basis for the fine division of shale strata. The specific graptolite species / genera only develop in a certain period of sedimentary environment, and this specific period also has a certain sedimentary environment and sedimentary shale corresponding to it. Graptolite is the "scale" for the division and correlation of black shale strata in the Wufeng-Luomaxi Formation. According to the fossil types of graptolite, the shale can be biochronologically divided. The author uses the graptolite zone division code of Chen Xu et al. for the graptolite zones of the Wufeng-Luomaxi shale. The 13 graptolite zone codes from bottom to top are WF1, WF2, WF3, WF4, LM1, LM2, LM3, LM4, LM5, LM6, LM7, LM8 and LM9, which correspond to Dicellograptus complanatus zone, Dicellograptus complexus zone, Paraorthograptus pacificus zone, Metabolograptus extraordinarius zone, Metabolograptus persculptus zone, Akidograptus ascensus zone, Parakidograptus acuminatus zone, Cystograptus vesiculosus zone, Coronograptus cyphus zone, Demirastrites triangulatus zone, Lituigraptus convolutus zone, Stimulograptus sedgwickii zone and Spirograptus guerichi zone. The bottom shale of the Wufeng-Luomaxi Formation (i.e. WF2-LM4 graptolite zone) has good shale gas enrichment conditions and exploration and development potential, and is the main gas production layer of Jiaoshiba, Weiyuan, Changning-Zhaotong and other national shale gas demonstration areas. In areas where the thickness of WF2-LM4 graptolite zone is thin or some graptolite zones are missing, the drilling effect of shale gas is usually not ideal, and the deployment of well sites and the exploration of Luomaxi shale gas in these areas need to be extra careful. Accurate characterization and thickness determination of the development of WF2-LM4 graptolite zone shale have become the key factors for the evaluation of enrichment and high yield targets and the achievement of exploration results in the Wufeng-Luomaxi shale gas in Sichuan Basin.

[0004] At present, the main method for exploration is to identify graptolite through drilling cores to divide graptolite zones and further determine the enrichment and high yield section of shale gas. Due to the high cost of drilling coring, the number of cored wells in shale gas development area is small, and the number of cored wells limits the large-scale application of traditional graptolite identification technology. The above problems seriously affect the evaluation and prediction effect of black shale favorable area, and affect the accuracy of shale gas exploration and development evaluation and selection. SUMMARY

[0005] The present application aims at overcoming the defects of the prior art, i.e. the high cost of drilling coring, the small number of coring wells in shale gas development zones, and the limitation of the number of coring wells on the large-scale popularization and application of the traditional penicillium identification technology, and provides a penicillium and electrical curve combined stratum division method and device.

[0006] The object of the present application can be achieved by the following technical solutions.

[0007] A penicillium and electrical curve combined stratum division method comprises the following steps:

[0008] Taking a coring well as a standard well, collecting natural gamma logging data of the standard well, and obtaining a natural gamma logging curve of the standard well after pretreatment;

[0009] Carrying out genus and species identification on shale penicillium of the standard well to obtain penicillium stratification;

[0010] Classifying regions according to the sedimentary environment of the standard well;

[0011] Establishing a corresponding relationship between the penicillium stratification of the standard well and the natural gamma logging curve of the standard well, and confirming the positions of the penicillium zones;

[0012] Collecting a natural gamma logging curve from a new well to obtain a natural gamma logging curve of the new well;

[0013] According to the sedimentary environment of the region where the new well is located, matching the corresponding natural gamma logging curve of the standard well from the corresponding region classification, and taking the penicillium stratification corresponding to the natural gamma logging curve of the standard well as the penicillium stratification of the new well.

[0014] Further, a curve space similarity comparison method is used to establish the corresponding relationship between the penicillium stratification and the natural gamma logging curve of the standard well.

[0015] Further, the curve space similarity comparison method comprises the following steps:

[0016] Two curves A1B1 and A2B2 to be compared are obtained, the curve A1B1 and the curve A2B2 are located in the same coordinate system, a point O is taken as the intersection of the extensions of line segments A2A1 and B1B2, n-2 P points are selected from the curve A1B1 except the parts of end points A1 and B1 to form a set P={A1, P1, P2, …, Pn-2, B1};

[0017] ∠A2OB2 is divided into n-2 parts, and the angles are α1, α2, …, αn-2; in the process of dividing ∠A2OB2, the points P1, P2, …, Pn-2 are ensured to be in different small angles αi (i = 1, 2, …, n-2); in the part of the curve A2B2 between the angles αi, ki points are selected, and are sequentially recorded as Qi1, Qi2, …, Qiki (ki ∈ N+), and a set Q is obtained:

[0018] Q = {A2, Q11, Q12, …, Q1k1, Q21, Q22, …, Q2k2, …, Qn-2,1, Qn-2,kn-2, B2}

[0019] The following values are calculated respectively:

[0020]

[0021] In the formula, |·| is the distance between two points;

[0022] The above values are sequentially set as d1, d2, …, dn, and D = {d1, d2, …, dn} is called the ratio sample of the sets P and Q corresponding to the curves A1B1 and A2B2; if the ratio sample falls in the confidence interval of the corresponding probability, the curves A1B1 and A2B2 are similar, otherwise, they are not similar.

[0023] Further, the curve space similarity comparison method is used to match the corresponding standard well natural gamma ray logging curve according to the new well natural gamma ray logging curve.

[0024] Further, the positions of the various graptolite zones are preliminarily confirmed according to the corresponding relationship between the graptolite layering and the standard well natural gamma ray logging curve.

[0025] The upper boundary of the graptolite zone corresponding to the local peak on the natural gamma ray logging curve is determined according to the half amplitude of the local minimum value or maximum value in the upward direction of the local peak, and the refined position of each graptolite zone is obtained.

[0026] Further, the standard well is classified according to the sedimentary environment in which it is located, specifically:

[0027] The standard well is classified into a deep water shelf sedimentary area, a semi-deep water shelf area and a shallow water shelf area according to the sedimentary environment in which it is located.

[0028] Further, in the deep water shelf sedimentary area, the deep water shelf facies is identified by black shale (TOC > 2%) rich in organic matter, including siliceous shale facies, calcareous siliceous mixed shale facies and clayey siliceous mixed shale facies.

[0029] In the semi-deep water shelf area, the semi-deep water shelf lithofacies association is mainly dark gray, gray black shale with medium organic matter content (TOC 1%~2%) and high clay content, including siliceous shale facies, clay shale facies, clay-siliceous mixed shale facies and clay-calcic mixed shale facies;

[0030] In the shallow water shelf area, the shallow water shelf lithofacies association is mainly gray, gray green shale with poor organic matter (TOC <1%) and rich clay, including clay shale facies, clay-siliceous mixed shale facies, clay-calcic mixed shale facies and calcic shale facies.

[0031] Further, according to the identification results of the shale graptolite genus and species of the standard well, the longitudinal distribution characteristics of the fossils are obtained, and then compared with the international standard graptolite fossil zone to obtain graptolite stratification;

[0032] The genus and species identification of the shale graptolite of the standard well includes: describing and identifying the morphology, the type of the cell tube and the development characteristics of the initial end of the graptolite, and measuring the characteristic parameters of the graptolite body;

[0033] The description type of the morphology of the graptolite includes one or more of bifurcate type, multi-fork type, single branch type, cell tube branching type, rake type, straight tube type, tower type and spiral type; the description type of the type of the cell tube includes one or more of uniform graptolite type, single graptolite type, roll graptolite type, half-rake graptolite type, rake graptolite type, thread graptolite type, fork graptolite type, nodule graptolite type and Chinese graptolite type; the characteristic parameters of the graptolite body include one or more of graptolite body length, graptolite body width, cell tube height, initial end width, embryonic tube length, distance between embryonic tube mouth and first row of cell tubes, cell tube mouth width, ratio of cell tube mouth width to graptolite body width, cell tube overlap, distance between cell tubes, initial end cell tube number, cell tube inclination angle, line tube length, embryonic tube spine length, spiral height and spiral width; the description type of the development characteristics of the initial end includes H type, I type and J type.

[0034] Further, the pretreatment is a normalization treatment, which includes selecting a marker layer, making a well logging histogram, a well correlation graph and a multi-well neutron density acoustic cross plot, determining a logging response standard, and then determining a correction amount, so as to realize the normalization of the natural gamma ray logging curve of the standard well in combination with auxiliary layer verification.

[0035] The application also provides a graptolite and electrical curve combined stratigraphic division device, which comprises a memory and a processor, the memory stores a computer program, and the processor calls the computer program to execute the steps of the method as described above.

[0036] Compared with the prior art, the application has the following advantages:

[0037] (1) The application determines the corresponding relationship between the graptolite zone type and the natural gamma (GR) logging curve of the area where the standard well is located by identifying the graptolite of the standard well; for a new well in the area, the position of the graptolite zone is preliminarily determined according to each local peak value of the GR logging curve, on the plane, the distribution area of different strata is divided according to the sedimentary environment and sedimentary facies, and the corresponding relationship between the graptolite zone type of the standard well and the GR logging curve is established in each area respectively.

[0038] By using this division scheme, without drilling and coring the new well, the shale gas rich and high-yield layer section can be quickly divided under the isochronous stratigraphic framework, and the prediction accuracy of the target area of the shale gas horizontal well is improved.

[0039] (2) The application proposes a method of using natural gamma curve and graptolite biological fossils to identify shale strata division and correlation, which provides an effective technical means for evaluating shale favorable sections, and has important significance for improving the effect of shale gas exploration and development. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 A flowchart of a graptolite and electrical curve combined stratigraphic division method provided in the embodiments of the application is shown;

[0041] Figure 2 A specific implementation process diagram for obtaining the position of each graptolite zone in the coring well is shown;

[0042] Figure 3 A natural gamma normalization histogram of the embodiments of the application is shown;

[0043] Figure 4 A frequency comparison diagram before and after the natural gamma logging normalization processing of the embodiments of the application is shown;

[0044] Figure 5 A graptolite fossil classification and identification diagram of the embodiments of the application is shown;

[0045] Figure 6 A graptolite biostratigraphic division diagram of the embodiments of the application is shown;

[0046] Figure 7 A curve similarity measurement diagram of the embodiments of the application is shown;

[0047] Figure 8 A curve similarity calculation diagram of the embodiments of the application is shown. DETAILED DESCRIPTION

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0049] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0050] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0051] Example 1

[0052] like Figure 1 As shown, this embodiment provides a stratigraphic division method combining graptolite and electrical property curves, including the following steps:

[0053] A1: Using the core well as a standard well, natural gamma ray logging data from the standard well is collected and preprocessed to obtain the natural gamma ray logging curve of the standard well; [The remaining text appears to be incomplete and requires further context.]

[0054] A2: The genus and species of graptolite in the shale of this standard well were identified, and the graptolite stratification was obtained;

[0055] A3: Regional classification based on the sedimentary environment of the standard wells;

[0056] A4: Establish the correspondence between the graptolite stratification of the standard well and the natural gamma logging curve of the standard well, and confirm the location of each graptolite zone;

[0057] A5: Acquire natural gamma logging curves from the new well;

[0058] A6: Based on the sedimentary environment of the area where the new well is located, match the corresponding natural gamma logging curve of the standard well from the corresponding regional classification, and use the graptolite strata corresponding to the natural gamma logging curve of the standard well as the graptolite strata of the new well.

[0059] The following is a detailed description of the specific implementation process for obtaining the location of each graptolite band in the core well:

[0060] like Figure 2 As shown, the specific steps include:

[0061] Step S1: As shown in Figure 3 and 4 , the natural gamma logging data of a shale gas coring well in the study area is collected and homogenized to obtain the corrected logging curve. The gamma curve normalization process: select the marker layer, make multi-well logging histogram, well correlation chart, multi-well neutron density acoustic cross plot, determine the logging response standard, and then determine the correction amount, perform normalization processing, and combine with auxiliary layer verification and several other steps to realize the normalization of the logging curve.

[0062] Step S2: Species identification of shale graptolite in the coring well, according to the longitudinal distribution characteristics of fossils and the comparison with the international standard graptolite fossil zone, the fine stratification of the stratum is completed;

[0063] Species identification includes: description and identification of the morphology of graptolite, the type of cell tube and the development characteristics of the beginning end, and the measurement of the characteristic parameters of graptolite body;

[0064] As shown in Figure 5 and 6 , the graptolite body morphology description classification is classified according to bifurcated type, multi-fork type, single branch type, cell tube branching type, rake type, straight pipe type, tower type and spiral type. The cell tube type description is classified according to the classification of equal division graptolite type, single graptolite type, scroll graptolite type, half rake graptolite type, rake graptolite type, thin graptolite type, fork graptolite type, nodule graptolite type and Chinese graptolite type. Graptolite body characteristic parameter measurement includes graptolite body length, graptolite body width, cell tube height, beginning end width, cell tube length, cell tube mouth and first row of cell tube distance, cell tube mouth width, cell tube mouth and graptolite body width ratio, cell tube overlap, cell tube distance, beginning end cell tube number, cell tube inclination angle, wire tube length, cell tube thorn length, spiral height, spiral width. Graptolite beginning end development type is classified according to H type, I type and J type.

[0065] Step S3: According to the sedimentary environment of the coring well, the coring well is classified according to deep water shelf sedimentary area, shallow water shelf area, semi-deep water shelf area, underwater uplift area and ancient land loss area. The identification mark of deep water shelf facies is black shale rich in organic matter (TOC>2%), including siliceous shale facies, calcareous siliceous mixed shale facies and clayey siliceous mixed shale facies. The main rock facies assemblage of semi-deep water shelf is dark gray, gray black shale with medium organic matter content (TOC1%~2%) and high clay content, including siliceous shale facies, clay shale facies, clay siliceous mixed shale facies and clay calcareous mixed shale facies. The main rock facies assemblage of shallow water shelf is gray, gray green shale with poor organic matter (TOC<1%) and rich clay, including clay shale facies, clay siliceous mixed shale facies, clay calcareous mixed shale facies and calcareous shale facies. Taking Well YS108 in southern Sichuan as the standard well, the total organic carbon TOC is greater than 2%, which is located in the deep water shelf area.

[0066] Step S4: For the natural gamma curve, the curve space similarity comparison method is used to establish the corresponding relationship between the graptolite layering and the natural gamma curve. The deep water shelf sedimentary area mainly includes the western Hubei-eastern Chongqing area, the southern Sichuan area and the northeastern Sichuan area. Taking the Shounan YS108 well as the standard well, the graptolite identification of the shale in the Wufeng Formation-Lower Longmaxi Formation of the Shounan YS108 well can obtain the graptolite zone division of the standard well.

[0067] As shown in Figure 7 and 8 , suppose there are curves A1B1 and A2B2, and they are placed in the same rectangular coordinate system. Connect points A1 and A2 with points B1 and B2, and the extensions of line segments A2A1 and B1B2 intersect at point O. In curve A1B1, any n-2 points are selected from the part excluding the end points A1 and B1, together with the end points A1 and B1, and are sequentially recorded as A1, P1, P2, …, Pn-2, B1. Obviously, when n→∞, curve A1B1 can be represented by set P:

[0068] P={A1,P1,P2,…,Pn-2,B1}

[0069] Asymptotically approximate. Again, ∠A2OB2 is divided into n-2 parts: α1, α2, …, αn-2. In the process of dividing ∠A2OB2, points P1, P2, …, Pn-2 are ensured to appear in different small angles αi (i=1, 2, …, n-2). In curve A2B2, any ki points are selected from the part between angles αi, and are sequentially recorded as Qi1, Qi2, …, Qiki (ki∈N+), as shown in Figure 2 . Similarly, when the number of selected points on curve A2B2 is sufficient, set Q={A2, Q11, Q12, …, Q1k1, Q21, Q22, …, Q2k2, …, Qn-2,1, Qn-2,kn-2, B2} can asymptotically approximate curve A2B2.

[0070] The following values are calculated respectively:

[0071]

[0072] In the formula, |·| is the distance between two points; that is, for any two points A(xA, yA) and B(xB, yB), there is:

[0073]

[0074] The above n values are sequentially set as d1, d2, …, dn, and D={d1, d2, …, dn} is called the ratio sample of sets P and Q corresponding to curves A1B1 and A2B2.

[0075] According to the Central Limit Theorem, if an outcome is caused by a large number of independent random factors, and each individual factor plays a small role in the total impact, then such a quantity follows or approximately follows a normal distribution.

[0076] Let D = {d1, d2, ..., dn} be a sample of the ratios of the sets P and Q corresponding to curves L and H, respectively. The mean of D is μ, and the variance is σ. If di falls within the confidence interval of the corresponding probability F(z), then:

[0077] di∈[μ-zσ,μ+zσ],i∈{1,2,…,n}, where z is the probability degree of the corresponding probability F(z). Commonly used corresponding values ​​between z and F(z) are shown in Table 1.

[0078] Table 1 shows the relationship between z and F(z).

[0079] z 1 1.65 1.96 2 2.58 3 F(z) 0.6827 0.9000 0.9500 0.9545 0.9900 0.9973

[0080] Then, the i-th point Pi in the set P corresponding to curve L is said to be similar to the set Q corresponding to curve H, or simply, point Pi is similar to set Q. If there are k such points Pi∈P that are similar to set Q, then k / n is called the similarity between the sets P and Q corresponding to curves L and H, denoted as SIM(P,Q)=k / n.

[0081] Given any two curves L1 and L2, divide them into 8 parts using the method described above, obtaining one set of data (see Table 2). In Table 2, D1 represents the distance from the intersection point O to several points in curve L1, and D2 represents the average distance from the intersection point O to several points in curve L2. D represents the ratio sample of D1 and D2. The similarity between the two curves is calculated using z = 1. At this point, the mean μ of the ratio sample is 1.7534, the root mean square σ is 0.1334, and the confidence interval with a probability of 68.27% is [1.6200, 1.8869]. The similarity between curves L1 and L2 is 60%. Similarly, the similarity between the two curves can be calculated for other z values. For example, when z = 3, the confidence interval is [1.3532, 2.1537], and the similarity between the two curves is 100%.

[0082] Table 2 Distance Samples of Curves

[0083] [D1] 1.7088 1.7671 1.7745 1.6978 1.6575 1.5232 1.5095 1.6735 1.8159 1.9679 [D2] 3.2696 2.7969 2.823 3.0005 2.7951 3.0466 2.7623 2.8071 3.2185 3.373 D 1.9133 1.5828 1.5909 1.7673 1.6864 2.0001 1.8299 1.6774 1.7724 1.714

[0084] Step S5: Based on the comparison results of the curve space similarity comparison method and the maximum peak value method of the natural gamma curve, the location of each graptolite zone is initially determined. The logging response of the graptolite zone in the Wufeng Formation shale usually includes two high GR values ​​and one low value, corresponding to the WF2, WF3, and WF4 graptolite zones, respectively. The half-amplitude value corresponding to the local peak of the two GR logging curves is the top and bottom boundary of the WF2, WF3, and WF4 graptolite zones.

[0085] Step S6: Determine the half amplitude of the local minimum or maximum adjacent to the local peak in the upward (shallow) direction on the GR logging curve as the upper boundary of the graptolite zone corresponding to the local peak. Based on the conventional graptolite identification, the shale of Wufeng Formation-Lower Longmaxi Formation in well JY1 is divided, and it can be determined that it contains WF2-WF4 graptolite zones and LM1-LM4 graptolite zones. The relationship between the graptolite zone and the GR value of its logging response is that after the WF4 graptolite zone, the logging response of the graptolite zone GR usually has three local high value zones and one local low value zone, which correspond to LM1, LM2, LM3 and LM4 graptolite zones respectively. The upper and lower half amplitude positions of the local peak of the GR logging curve are the top and bottom boundaries of the LM1, LM2, LM3 and LM4 graptolite zones.

[0086] In this embodiment, the curve space similarity comparison method is also used to match the corresponding standard well natural gamma logging curve according to the new well natural gamma logging curve.

[0087] The embodiment also provides a graptolite and electrical curve combined stratum division device, which comprises a memory and a processor, the memory stores a computer program, and the processor calls the computer program to execute the steps of the graptolite and electrical curve combined stratum division method as described above.

[0088] The preferred embodiments of the present application are described in detail above. It should be understood that those skilled in the art can make many modifications and changes without creative labor based on the concept of the present application. Therefore, any technical solution obtained by logical analysis, reasoning or limited experiment based on the prior art according to the concept of the present application shall be within the protection scope determined by the claims.

Claims

1. A method for combined use of graptolite and electrical property curves for stratigraphic division, characterized by, The method comprises the following steps: The following steps are included: Taking a core well as a standard well, collecting natural gamma ray logging data of the standard well, and obtaining a natural gamma ray logging curve of the standard well after pretreatment; Shale graptolite of the standard well is identified by species to obtain graptolite stratification; The standard well is classified according to the sedimentary environment in which the standard well is located; The corresponding relationship between the graptolite stratification of the standard well and the natural gamma ray logging curve of the standard well is established to confirm the position of each graptolite zone; The natural gamma ray logging curve of the new well is collected to obtain the natural gamma ray logging curve of the new well; According to the sedimentary environment of the region where the new well is located, the corresponding standard well natural gamma ray logging curve is matched from the corresponding regional classification, and the graptolite stratification corresponding to the standard well natural gamma ray logging curve is taken as the graptolite stratification of the new well; The corresponding relationship between the graptolite stratification and the natural gamma ray logging curve of the standard well is established by using the curve space similarity comparison method; The curve space similarity comparison method comprises the following steps: Obtain two curves A1B1 and A2B2 to be compared, the curves A1B1 and A2B2 are located in the same coordinate system, take the intersection point of the extension lines of line segments A2A1 and B1B2 as point O, and remove the parts of end points A1 and B1 in curve A1B1 to arbitrarily select n-2 P points to form set P={A1, P1, P2, …, Pn-2, B1}; Divide ∠A2OB2 into n-2 parts to obtain angles: α1, α2, …, αn-2, and ensure that points P1, P2, …, Pn-2 appear in different small angles αi during the division of ∠A2OB2, i=1, 2, …, n-2; In the part of curve A2B2 clamped in angle αi, arbitrarily select ki points and sequentially record them as Qi1, Qi2, …, Qiki, ki∈N+, and obtain set Q={A2, Q11, Q12, …, Q1k1, Q21, Q22, …, Q2k2, …, Qn-2,1, Qn-2,kn-2, B2} Calculate the following values respectively: wherein is the distance between two points; Set the above values as d1, d2, …, dn in turn, and call D={d1, d2, …, dn} as the ratio sample of corresponding sets P and Q of curves A1B1 and A2B2, if the ratio sample falls in the confidence interval of the corresponding probability, then the curves A1B1 and A2B2 are similar, otherwise they are not similar; The corresponding natural gamma ray logging curve of the standard well is matched according to the natural gamma ray logging curve of the new well by using the curve space similarity comparison method.

2. The method according to claim 1, wherein the method is characterized by, According to the corresponding relationship between the graptolite stratification and the natural gamma ray logging curve of the standard well, the position of each graptolite zone is preliminarily confirmed; According to the half amplitude corresponding to the local minimum or maximum value of the local peak in the upward direction on the natural gamma ray logging curve, the upper boundary of the graptolite zone corresponding to the local peak is determined to obtain the refined position of each graptolite zone.

3. The method according to claim 1, wherein the method is characterized by, The regional classification according to the sedimentary environment in which the standard well is located is specifically: The standard well is classified into a deep water shelf sedimentary area, a semi-deep water shelf area and a shallow water shelf area according to the sedimentary environment in which the standard well is located; The deep water shelf sedimentary area is rich in black shale with TOC>2%, including siliceous shale facies, calcareous siliceous mixed shale facies and clayey siliceous mixed shale facies; The semi-deep water shelf area is mainly composed of dark grey and grey black shale with medium organic matter content and high clay content, the medium organic matter content corresponds to TOC of 1% to 2%, including siliceous shale facies, clayey shale facies, clayey siliceous mixed shale facies and clayey calcareous mixed shale facies; The shallow water shelf area is mainly composed of grey and grey green shale with poor organic matter content and rich clay content, the poor organic matter content corresponds to TOC<1%, including clayey shale facies, clayey siliceous mixed shale facies, clayey calcareous mixed shale facies and calcareous shale facies.

4. The method according to claim 1, wherein the method is characterized by, According to the identification results of the shale graptolite genus of the standard well, the longitudinal distribution characteristics of the fossils are obtained, and then compared with the international standard graptolite fossil zone to obtain the graptolite stratification; The genus identification of the shale graptolite of the standard well includes: describing and identifying the morphology, the theca type and the initial end development characteristics of the graptolite, and measuring the graptolite body characteristic parameters; The morphological description of the graptolite includes one or more of bifurcate type, multi-furcate type, single branch type, theca branching type, rake type, straight tube type, tower type and spiral type; the description type of the theca type includes one or more of uniform graptolite type, single graptolite type, volutella type, half-rake graptolite type, rake graptolite type, thread graptolite type, fork graptolite type, nubecular graptolite type and Chinese graptolite type; the graptolite body characteristic parameters include one or more of graptolite body length, graptolite body width, theca height, initial end width, embryonic tube length, distance between embryonic tube mouth and first row of theca, theca mouth width, theca mouth to graptolite body width ratio, theca overlap, theca distance, initial end theca number, theca inclination angle, line tube length, embryonic tube spine length, spiral height and spiral width; the description type of the initial end development characteristics includes H type, I type and J type.

5. The method according to claim 1, wherein the method is characterized by, The pretreatment is a homogenization treatment, which includes selecting a marker layer, making a well logging histogram, a well correlation graph and a multi-well neutron density acoustic cross plot, determining a logging response standard, and then determining a correction amount, so as to realize the normalization of the standard well natural gamma logging curve.

6. A device for combining the graptolite and electrical property curves for stratigraphic division, characterized by, The computer program is stored in the memory and called by the processor to execute the steps of the method of any one of claims 1 to 5. The computer program is stored in the memory and called by the processor to execute the steps of the method of any one of claims 1 to 5.

Images