A natural water-flooded reservoir identification method and related device

Abstract

The application provides a natural water-flooded oil layer identification method and related device, the method comprises the following steps: obtaining the logging response characteristic parameters of conventional oil layers, poor oil layers, natural water-flooded oil layers and water layers of a coring well of a structure-adjusted reservoir; calculating the natural potential relative value parameters and resistivity ratios by using the logging response characteristic parameters; obtaining the demarcation thresholds of the natural potential relative value parameters and the resistivity ratios by using the intersection distribution of the natural potential relative value parameters and the resistivity ratios; calculating the natural potential relative value parameters and the resistivity ratios of a non-coring well to be identified; and matching the natural potential relative value parameters and the resistivity ratios of the non-coring well to be identified with the demarcation thresholds to identify the oil layers, the poor oil layers, the natural water-flooded oil layers and the water layers of the non-coring well. The application is beneficial to accurately describing the oil-water interface morphology of the structure-adjusted reservoir, can improve the calculation accuracy of the original oil geological reserves of the structure-adjusted reservoir and guide the optimization of the perforation scheme of the oil well.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas field development, and particularly relates to a natural water-flooded oil layer identification method and related device. BACKGROUND

[0002] The natural water-flooded oil layer refers to a pre-existing reservoir formed by oil and gas migration of hydrocarbon source rock hydrocarbon expulsion. The late orogenic movement causes the pre-existing structure to tilt and other effects, and part of the oil in the pre-existing reservoir is lost to form a structural adjustment reservoir (oilfield). At the same time, the formation water invades part of the oil layer of the structural adjustment reservoir (oilfield) to form a natural water-flooded oil layer (water-flooded layer), and causes the oil-water interface of the structural adjustment reservoir (oilfield) to tilt.

[0003] Many oil reservoirs in China have experienced structural tilting, resulting in natural water-flooding of oil layers and tilting of oil-water interfaces. Many oil reservoirs abroad also have natural water-flooded oil layers and tilted oil-water interfaces.

[0004] At the early stage of development of the structural adjustment reservoir (oilfield), due to the limitations of the acquired data and people's understanding, the natural water-flooded oil layer is often mistaken for a poor oil layer, resulting in unreasonable well perforation, short no-water oil production period, low calculation accuracy of original oil geological reserves, and other problems. Therefore, an accurate and effective natural water-flooded layer identification technology is urgently needed to accurately identify the natural water-flooded layer and the oil layer. SUMMARY

[0005] In order to effectively identify the natural water-flooded oil layer and improve the prediction accuracy of oil well productivity and the calculation accuracy of original oil geological reserves, the present application provides a natural water-flooded oil layer identification method and related device.

[0006] A natural water-flooded oil layer identification method, comprising the following steps:

[0007] Obtaining the logging response characteristic parameters of the conventional oil layer, poor oil layer, natural water-flooded oil layer and water layer of the core well of the structural adjustment reservoir, the logging response characteristic parameters at least including the spontaneous potential SP, deep resistivity Rt, shallow resistivity Rs and invasion zone resistivity Rxo;

[0008] Using the logging response characteristic parameters to calculate the spontaneous potential relative value parameters and resistivity ratio of the conventional oil layer, poor oil layer, natural water-flooded oil layer and water layer, wherein the spontaneous potential relative value parameters are used to reflect the differences in the spontaneous potential of the conventional oil layer, water-flooded layer and water layer at different well points, and the resistivity ratio parameters are used to reflect the differences in the resistivity value distribution and ratio change rule between the conventional oil layer, poor oil layer, water-flooded layer and water layer;

[0009] Using the intersection distribution of the spontaneous potential relative value parameters and resistivity ratio, the boundary threshold values of the conventional oil layer, poor oil layer, natural water-flooded oil layer and water layer in the spontaneous potential relative value parameters and resistivity ratio are obtained.

[0010] obtaining the logging response characteristic parameters of the non-coring well to be identified, calculating the spontaneous potential relative value parameters and the resistivity ratio of the non-coring well to be identified;

[0011] matching the spontaneous potential relative value parameters and the resistivity ratio of the non-coring well to be identified with the demarcation threshold, identifying the oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer of the non-coring well.

[0012] Further, before obtaining the logging response characteristic parameters of the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer of the coring well of the structural adjustment reservoir, the following steps are further included:

[0013] selecting the coring well of the structural adjustment reservoir, the coring well including the natural water-flooded layer, and determining the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer according to the core display characteristics.

[0014] Further, the calculation of the spontaneous potential relative value parameters by using the logging response characteristic parameters includes calculating the spontaneous potential relative value parameters according to a preset first formula:

[0015]

[0016] In the formula, RSP represents the spontaneous potential relative value SP, SP max , SP min respectively represent the spontaneous potential value of any point, the maximum value and the minimum value of the spontaneous potential of the target layer section.

[0017] Further, the calculation of the resistivity ratio by using the logging response characteristic parameters includes calculating the resistivity ratio according to a preset second formula:

[0018]

[0019] In the formula, RR represents the resistivity relative value, R t , R s , R xo respectively represent the deep resistivity, the shallow resistivity and the invasion zone resistivity of the formation.

[0020] Further, the calculation of the spontaneous potential relative value parameters and the resistivity ratio of the non-coring well to be identified includes:

[0021] obtaining the spontaneous potential SP, the deep resistivity Rt, the shallow resistivity Rs and the invasion zone resistivity Rxo of the non-coring well to be identified;

[0022] obtaining the spontaneous potential relative value parameters according to the preset first formula, and obtaining the resistivity ratio according to the preset second formula.

[0023] Further, the natural potential relative value parameter and the resistivity ratio of the non-coring well to be identified are matched with the preset boundary threshold value, and the oil layer, poor oil layer, natural water flooded oil layer and water layer of the coring well are identified, and the conventional oil layer and poor oil layer need to be distinguished by combining the natural gamma and the deep resistivity.

[0024] In another aspect, the application further discloses a natural water flooded oil layer identification method, comprising the following steps:

[0025] The logging response characteristic parameters of the non-coring well to be identified are obtained, and the natural potential relative value parameter and the resistivity ratio of the non-coring well to be identified are calculated, wherein the logging response characteristic parameters at least include the natural potential, the deep resistivity, the shallow resistivity and the invasion zone resistivity;

[0026] The natural potential relative value parameter and the resistivity ratio of the non-coring well to be identified are matched with the preset boundary threshold value, and the conventional oil layer, poor oil layer, natural water flooded oil layer and water layer of the coring well are identified, and the preset boundary threshold value is the natural potential relative value parameter and the resistivity ratio that need to be met simultaneously by the conventional oil layer, poor oil layer, natural water flooded oil layer and water layer.

[0027] In a third aspect, the application further discloses a natural water flooded oil layer identification device, comprising a logging response characteristic parameter acquisition module, a first calculation module, a boundary threshold value generation module, a second calculation module and an identification module, wherein:

[0028] The logging response characteristic parameter acquisition module is used to obtain the logging response characteristic parameters of the conventional oil layer, poor oil layer, natural water flooded oil layer and water layer of the coring well of the structure adjusted reservoir, and the logging response characteristic parameters at least include the natural potential SP, deep resistivity Rt, shallow resistivity Rs and invasion zone resistivity Rxo;

[0029] The first calculation module is used to calculate the natural potential relative value parameter and the resistivity ratio of the conventional oil layer, poor oil layer, natural water flooded oil layer and water layer by using the logging response characteristic parameters, wherein the natural potential relative value parameter is used to reflect the difference of the natural potential of the conventional oil layer, water flooded layer and water layer at different well points, and the resistivity ratio parameter is used to reflect the difference of the resistivity value distribution and the resistivity ratio change rule between the conventional oil layer, poor oil layer, water flooded layer and water layer;

[0030] The boundary threshold value generation module is used to obtain the boundary threshold value of the natural potential relative value parameter and the resistivity ratio of the conventional oil layer, poor oil layer, natural water flooded oil layer and water layer by using the intersection distribution of the natural potential relative value parameter and the resistivity ratio;

[0031] The second calculation module is used to calculate the natural potential relative value parameter and the resistivity ratio of the non-coring well to be identified;

[0032] The identification module is used for matching the relative value parameter of the spontaneous potential and the resistivity ratio of the non-coring well to be identified with the demarcation threshold value, and identifying the oil layer, poor oil layer, natural water-flooded oil layer and water layer of the non-coring well.

[0033] Based on the above technical solution, the present application has the following beneficial effects compared with the prior art:

[0034] According to the similarities and differences between the natural water-flooded oil layer and the poor oil layer, the demarcation threshold value of the relative value parameter of the spontaneous potential and the resistivity ratio of the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer is calculated based on the spontaneous potential and resistivity logging response; and then the relative value parameter of the spontaneous potential and the resistivity ratio of the non-coring well to be identified are matched with the demarcation threshold value, so that the oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer of the non-coring well can be effectively identified. The present application is beneficial to accurately describing the oil-water interface morphology of the structural adjustment reservoir, can improve the calculation accuracy of the original oil geological reserves of the structural adjustment reservoir, and guides the optimization of the oil well perforation scheme. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the following specific embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0036] Figure 1 For the embodiment one of the present application, a flowchart of a natural water-flooded oil layer identification method is shown in the figure.

[0037] Figure 2 For the embodiment one of the present application, a core diagram of the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer is shown in the figure.

[0038] Figure 3 For the embodiment one of the present application, a comprehensive columnar chart of a certain well is shown in the figure.

[0039] Figure 4 For the embodiment one of the present application, a spontaneous potential relative value RSP and resistivity ratio RR intersection diagram of a certain oilfield is shown in the figure.

[0040] Figure 5 For the embodiment two of the present application, a flowchart of another natural water-flooded oil layer identification method is shown in the figure.

[0041] Figure 6 For the embodiment three of the present application, a structural diagram of a natural water-flooded oil layer identification device is shown in the figure.

[0042] Figure 7For the fourth embodiment of the present application, another natural water-flooded reservoir identification device is shown in the structural schematic view. DETAILED DESCRIPTION

[0043] The inventors have found through a large number of studies that the tectonic adjustment reservoir is formed in advance, and the later tectonic tilting caused by orogenic movement leads to the displacement of part of the oil layer by formation water, forming a natural water-flooded reservoir (water-flooded layer). Therefore, in the tectonic adjustment reservoir, there exist conventional oil layers, poor oil layers, natural water-flooded reservoirs, and water layers, etc. In the case of less data and limited understanding, the natural water-flooded reservoir is easily misjudged as a poor oil layer, leading to unreasonable well perforation, short no-water oil production period, and low calculation accuracy of the original oil geological reserves.

[0044] The natural water-flooded reservoir of the tectonic adjustment reservoir has certain similarity with the poor oil layer, and the common points of the two mainly lie in: 1. The deep resistivity logging values of both are low. The formation resistivity of both is lower than that of the conventional oil layer, but higher than that of the water layer, and overall, they all show the feature of relatively low deep resistivity. 2. The oil saturation of both is low. According to the oil saturation logging interpretation formula, the oil saturation of both is generally lower than that of the conventional oil layer.

[0045] Although the natural water-flooded reservoir has certain similarity with the poor oil layer, the difference is also very obvious. The different points of the two mainly lie in the following five aspects: 1. The genetic mechanism is different. The natural water-flooded reservoir is caused by the tectonic tilting of orogenic movement, which leads to the displacement of part of the oil layer by formation water, resulting in low oil saturation and low resistivity; while the poor oil layer is caused by low porosity and low permeability, resulting in low oil saturation and low resistivity. 2. The core direct display is different. The core of the poor oil layer is low oil content such as oil immersion or oil spots, and the oil content is uneven, but the core only contains oil and no water, the water droplet is "spherical", and the color of the core is basically the same as that of the conventional oil layer; the natural water-flooded reservoir shows the feature of "water-flooded", the core contains both oil and water, the water droplet is "hemispherical" or rapidly penetrates, and the color of the core is dark brown, which is darker than that of the conventional oil layer. 3. The logging response is different. The spontaneous potential characteristics of the poor oil layer are similar to those of the oil layer, and the resistivity is relatively high; while the spontaneous potential curve characteristics of the natural water-flooded reservoir are similar to those of the water-flooded layer, and the resistivity is relatively low. The first and second points are the basis of the third point. From the other two angles, the inventors have also found two difference points, i.e. 4. The spatial position of the distribution is different. The poor oil layer is generally inter-distributed with the conventional oil layer, while the natural water-flooded reservoir generally appears at the bottom of the conventional oil layer, at the top of the "bottom water" or "oil-water transition zone" of the ancient oil reservoir. 5. The productivity is different. The poor oil layer has low porosity and low permeability, and although its productivity is low, it generally does not produce water; the productivity of the natural water-flooded layer is relatively high, but its water production rate is relatively high, and the oil production is low or even no oil production.

[0046] According to the similarities and differences between the natural water-flooded oil layer and the poor oil layer, the inventor finds that the difference based on the third point is easier to quantify, and thus proposes a natural water-flooded oil layer identification method.

[0047] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in combination with the drawings of the specification and specific embodiments.

[0048] Embodiment one

[0049] A natural water-flooded oil layer identification method, in combination with Figure 1 As shown in the figure, it includes steps S110-S150, specifically:

[0050] Step S110, obtaining the logging response characteristic parameters of the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer of the core well for adjusting the reservoir, the logging response characteristic parameters at least including the spontaneous potential SP, the deep resistivity Rt, the shallow resistivity Rs and the invasion zone resistivity Rxo.

[0051] In combination with Figure 3 As shown in the figure, specifically, the logging response characteristic parameters of the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer can be directly obtained through the open hole logging, wherein:

[0052] The spontaneous potential SP of the conventional oil layer presents a large negative anomaly, although the invasion zone resistivity Rxo is relatively high, but there is a large positive difference between the shallow resistivity Rs curve and the deep resistivity Rt curve, the invasion zone resistivity Rxo, the shallow resistivity Rs curve and the deep resistivity Rt satisfy the following relationship: Rt> Rs>> Rxo, and the shallow resistivity Rs curve and the deep resistivity Rt are both relatively large.

[0053] The spontaneous potential SP of the poor oil layer presents a large negative anomaly, the invasion zone resistivity (Rxo) is still relatively high, but still presents a low-amplitude positive difference between the shallow resistivity (Rs) curve and the deep resistivity (Rt) curve; the deep resistivity and the shallow resistivity are both lower than those of the conventional oil layer, and present a small positive difference between them, the invasion zone resistivity Rxo, the shallow resistivity Rs curve and the deep resistivity Rt satisfy the following relationship: Rt> Rs> Rxo.

[0054] The spontaneous potential of the natural water-flooded oil layer presents a negative anomaly, but the anomaly amplitude is relatively low compared with the conventional oil layer or the poor oil layer; the deep resistivity value Rt, the shallow resistivity value Rs and the invasion zone resistivity value Rxo are all significantly lower than those of the conventional oil layer or the poor oil layer, the deep resistivity Rt is basically close to the shallow resistivity Rs curve, and presents a low-amplitude positive difference between the shallow resistivity (Rs) curve, the invasion zone resistivity Rxo, the shallow resistivity Rs curve and the deep resistivity Rt satisfy the following relationship: Rt≈ Rs> Rxo.

[0055] The formation water in the aquifer has high salinity and strong conductivity. Its resistivity is less than 1 Ω·m. Both the deep and shallow resistivity are slightly lower than the resistivity of the intrusive zone, showing an overall increasing resistivity trend, but the three are essentially similar. The resistivity curves of the intrusive zone (Rxo), the shallow resistivity (Rs), and the deep resistivity (Rt) satisfy the following relationship: Rt≈Rs <Rxo。

[0056] Understandably, before this step, it is necessary to determine the conventional oil layer, poor oil layer, and naturally water-flooded oil layer of the cored well based on the core display characteristics. Based on the differences in fluids contained in the underground reservoir and the reservoir quality, the oil-water layers of structurally adjusted oil reservoirs (oilfields) are divided into oil layers, poor oil layers, naturally water-flooded oil layers, and water layers. Reservoirs with good reservoir quality and saturated with oil are oil layers; reservoirs with poor reservoir quality and relatively low oil saturation are poor oil layers; oil layers with good reservoir quality where some oil has been displaced by formation water due to tectonic movement are naturally water-flooded oil layers; and reservoirs that are consistently saturated with formation water are water layers. Specifically, combined with... Figure 2 As shown, core samples were taken from typical systematic core wells of structurally adjusted reservoirs to observe the core characteristics of conventional oil layers, poor oil layers, naturally water-flooded oil layers, and water layers. Cores from conventional oil layers are light brown with relatively high porosity and minimal variation; they are predominantly oil-rich and saturated, and water droplets form spherical shapes. Cores from poor oil layers are also light brown, with significant variations in lithological properties. Areas with relatively high porosity are predominantly oil-impregnated, and water droplets form spherical shapes; areas with low porosity and relatively poor properties have poor or no oil content, and the oil content is unevenly distributed. Cores from naturally water-flooded oil layers have relatively high porosity and relatively good properties, but are not fully oil-saturated, mainly showing oil spots, primarily dark brown in color, and water droplets penetrate rapidly or form hemispherical shapes, exhibiting hydrophilic characteristics. Cores from water layers are essentially oil-free, grayish-white, strongly hydrophilic, and penetrate rapidly after water droplets are applied.

[0057] This step identifies oil layers, poor oil layers, naturally water-flooded oil layers, and water layers based on the oil-bearing properties, reservoir properties, and formation mechanisms of various oil and water layers shown in the core samples. Then, using the logging response characteristic parameters obtained from open-hole logging, the corresponding relationships of various logging response parameter characteristics such as spontaneous potential SP, deep resistivity Rt, shallow resistivity Rs, and invasive zone resistivity Rxo are established for oil layers, poor oil layers, naturally water-flooded oil layers, and water layers.

[0058] Step S120: Calculate the relative values ​​of the natural potential and resistivity ratios of the conventional oil layer, poor oil layer, naturally water-flooded oil layer, and water layer using the well logging response characteristic parameters. The relative values ​​of the natural potential are used to reflect the differences in the natural potential of the conventional oil layer, water-flooded layer, and water layer at different well points. The resistivity ratios are used to reflect the differences in the distribution and ratio of resistivity values ​​among the conventional oil layer, poor oil layer, water-flooded layer, and water layer.

[0059] The person skilled in the art can understand that when the pressure and salinity of the formation water and the drilling fluid are different, the anions and cations will diffuse in different directions, the rock particles will differentially adsorb the ions, thus generating diffusion electromotive force and adsorption electromotive force near the well wall, and forming a natural electric field. The natural electric potential logging is a logging method for measuring the natural electric field potential of each formation during drilling. The measured potential value only represents the relative height of the natural electric potential, and there is no absolute zero line.

[0060] In order to quantitatively reflect the difference of the natural electric potential of the oil layer, the watered-out layer and the water layer at different well points, the relative value (RSP) of the natural electric potential is introduced, and the expression of the preset first formula is:

[0061]

[0062] In the formula, RSP represents the relative value of the natural electric potential, which is dimensionless, and the value is between 0 and 1, SP, SPmax and SPmin represent the natural electric potential value of an arbitrary point, the maximum value and the minimum value of the natural electric potential of the target layer section, respectively, and mV. max min

[0063] Since the measured value of the natural electric potential of the oil layer is closer to the minimum value of the natural electric potential, and the measured value of the natural electric potential of the watered-out layer and the water layer is closer to the maximum value of the natural electric potential, after the above data transformation processing, the RSP value of the oil layer is close to 1, and the RSP values of the watered-out layer and the water layer are closer to 0. The formula converts the measured natural electric potential value of different well points into the relative value of the natural electric potential between 0 and 1, which is dimensionless, thereby eliminating the influence of the logging instrument, the logging environment and the like on the natural electric potential logging response.

[0064] In addition, the inventor finds that the amplitude difference Rt / Rxo, Rs / Rxo between the deep resistivity Rt, the shallow resistivity Rs and the invasion zone resistivity Rxo is not equal among the oil layer, the poor oil layer, the watered-out layer and the water layer. Considering the distribution of the resistivity value and the change rule of the ratio of the resistivity values, the resistivity ratio parameter RR can better reflect the difference among the oil layer, the poor oil layer, the watered-out layer and the water layer, and the specific calculation formula is the preset second formula:

[0065]

[0066] In the formula, RR represents the relative value of the resistivity, which is dimensionless, and RR t s xo Rt, Rs and Rxo represent the deep resistivity, the shallow resistivity and the invasion zone resistivity of the formation, respectively, and the unit is Ω.m.

[0067] ​​​​Step S130, obtaining the threshold of the natural potential relative value parameter and the resistivity ratio value of the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer by using the intersection distribution of the natural potential relative value parameter and the resistivity ratio value.

[0068] Based on the intersection graph and data statistics of the natural potential relative value RSP and the resistivity ratio RR of various oil and water layers, the classification boundaries of the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer are determined.

[0069] In combination with Figure 4 As shown in the figure, the distribution ranges of the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer on the intersection graph of the natural potential relative value RSP and the resistivity ratio RR have obvious differences. The conventional oil layer and the poor oil layer are distributed in the upper right corner of the intersection graph, although they have overlapping and intersecting parts, but there is still obvious difference between them and the water-flooded layer, mainly reflected in that the natural potential relative value RSP of the oil layer and the poor oil layer is greater than 0.5 and 0.44 respectively, while the natural potential relative value RSP of the water-flooded layer is between 0.12 and 0.44; the resistivity ratio RR of the oil layer and the poor oil layer is greater than 0.5, while the resistivity ratio RR of the water-flooded layer is between 0 and 1. As for the same well, the deep resistivity value Rt of the water-flooded layer is lower than that of the poor oil layer, so it is easier to distinguish. The natural potential relative value RSP of the water layer is less than 0.12, and the resistivity ratio RR is less than 0, both of which are relatively low and easy to identify. Table 1 shows the threshold of the natural potential relative value parameter and the resistivity ratio value of the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer.

[0070] Step S140, obtaining the logging response characteristic parameters of the non-coring well to be identified, and calculating the natural potential relative value parameter and the resistivity ratio value of the non-coring well to be identified.

[0071] Specifically, the natural potential SP, the deep resistivity Rt, the shallow resistivity Rs and the invasion zone resistivity Rxo of the non-coring well to be identified are obtained; the natural potential relative value parameter is obtained by using a preset first formula, and the resistivity ratio value is obtained by using a preset second formula.

[0072] The preset first formula is:

[0073]

[0074] In the formula, RSP represents the natural potential relative value, which is dimensionless and its value is between 0 and 1, SP, SP max , and SP min respectively represent the natural potential value of any point, the maximum value and the minimum value of the natural potential of the target layer section, mV.

[0075] The preset second formula is:

[0076]

[0077] In the formula: RR represents resistivity relative value, dimensionless, R t , R s , R xo respectively represent deep resistivity, shallow resistivity and invasion zone resistivity of the formation, unit: Ω.m.

[0078] In step S150, the spontaneous potential relative value parameter and the resistivity ratio of the non-coring well to be identified are matched with the demarcation threshold value, and the oil layer, poor oil layer, natural water-flooded oil layer and water layer of the coring well are identified.

[0079] The spontaneous potential relative value parameter and the resistivity ratio of the non-coring well to be identified are matched with the demarcation threshold value in Table 1, and the oil layer, poor oil layer, natural water-flooded oil layer and water layer of the coring well are identified.

[0080] By using the method of the embodiment of the application, the inventor effectively identifies the conventional oil layer, poor oil layer and water-flooded layer of six oil wells in an oilfield, and the oil layer classification result is verified by actual production test, thereby effectively guiding the optimization of the oil well perforation scheme and the prediction of the oil-water interface of the oilfield.

[0081] In some embodiments, after the spontaneous potential relative value parameter and the resistivity ratio of the non-coring well to be identified are matched with the demarcation threshold value, the oil layer, poor oil layer, natural water-flooded oil layer and water layer of the coring well are identified, and the conventional oil layer and poor oil layer are further distinguished in combination with the natural gamma and deep resistivity of the formation, so that the natural gamma logging value is also obtained when logging is performed, and the main characteristics of the two types of oil layers are as follows:

[0082] The natural gamma value of the conventional oil layer is relatively low, and the deep resistivity is relatively large, the natural gamma logging value of the conventional oil layer is distributed between 7.8 and 18.5 API, and the average is 12.2 API; the deep resistivity logging value is distributed between 398.8 and 595 Ω.m, and the average is 146 Ω.m. The natural gamma value of the poor oil layer is relatively high, and the deep resistivity is relatively small, the natural gamma logging value of the poor oil layer is distributed between 19.8 and 37 API, and the average is 25 API; the deep resistivity logging value is distributed between 48 and 125 Ω.m, and the average is 73.6 Ω.m.

[0083] According to the similarities and differences between the natural water-flooded oil layer and the poor oil layer, the natural potential relative value RSP and the resistivity ratio RR are calculated based on the natural potential and resistivity logging responses, and the poor oil layer and the natural water-flooded oil layer can be quickly distinguished through the intersection of RSP and RR or the numerical size between RSP and RR.

[0084] The accurate identification of the natural water-flooded oil layer has the following advantages:

[0085] (1) It is beneficial to accurately describe the oil-water interface shape of the structural adjustment reservoir. The natural water-flooded oil layer generally appears at the bottom of the structural adjustment reservoir, and there is a "new" oil-water interface between the oil layer. Due to the difference in structural adjustment intensity and the change in structural space position, the thickness of the natural water-flooded oil layer of the structural adjustment reservoir at different well points is different. Based on the identification of the natural water-flooded oil layer of each well point, the spatial shape of the oil-water interface can be quantitatively characterized, and the occurrence of the oil-water interface is clarified, thereby providing a basis for the calculation of the original oil geological reserves and the optimization of perforation.

[0086] (2) It is beneficial to improve the calculation accuracy of the original oil geological reserves of the structural adjustment reservoir. Since the present application effectively distinguishes between poor oil layers and natural water-flooded oil layers, the thickness of the natural water-flooded oil layer can be effectively excluded when calculating the original oil geological reserves. At the same time, the present application can accurately describe that the oil-water interface of the structural adjustment reservoir is inclined rather than horizontal, so as to improve the calculation accuracy of the oil volume of the structural adjustment reservoir. The above two aspects show that accurate identification of the natural water-flooded oil layer is an important guarantee for accurate calculation of the original oil geological reserves of the structural adjustment reservoir.

[0087] (3) It can guide the optimization of oil well perforation scheme. The present application effectively identifies the natural water-flooded oil layer and the oil-water interface shape, can guide the optimization of the perforation interval of the oil well, and avoid misfiring the natural water-flooded oil layer. By reasonably optimizing the avoidance height of the oil well, the water-free oil production period of the oil well is prolonged, and the development effect of the oil well is maximized.

[0088] Embodiment two

[0089] In other embodiments, steps S110-S130 in embodiment one do not need to be performed every time, and the previously obtained demarcation threshold can be directly used for natural water-flooded oil layer identification.

[0090] As shown in Figure 5 A natural water-flooded oil layer identification method includes steps S210, S220:

[0091] Step S210, obtaining the logging response characteristic parameters of the non-coring well to be identified, calculating the spontaneous potential relative value parameters and resistivity ratio of the non-coring well to be identified, the logging response characteristic parameters at least including spontaneous potential, deep resistivity, shallow resistivity, and invasion zone resistivity.

[0092] The spontaneous potential SP, deep resistivity Rt, shallow resistivity Rs, and invasion zone resistivity Rxo of the non-coring well to be identified can be directly obtained by open hole logging; the spontaneous potential relative value parameters are obtained by using a preset first formula, and the resistivity ratio is obtained by using a preset second formula.

[0093] The preset first formula is:

[0094]

[0095] In the formula, RSP represents a natural potential relative value, dimensionless, with a value between 0 and 1, SP, SPmax and SPmin represent the natural potential value of an arbitrary point, the maximum value and the minimum value of the natural potential of a target layer, respectively, in mV. max min SPmax and SPmin represent the maximum value and the minimum value of the natural potential of a target layer, respectively, in mV.

[0096] A preset second formula is:

[0097]

[0098] In the formula, RR represents a resistivity relative value, dimensionless, Rdeep, Rshallow and Rinvade represent the deep resistivity, the shallow resistivity and the invasion zone resistivity of a formation, respectively, in Ω.m. t s xo Rdeep, Rshallow and Rinvade represent the deep resistivity, the shallow resistivity and the invasion zone resistivity of a formation, respectively, in Ω.m.

[0099] In step S220, the natural potential relative value parameter and the resistivity ratio of the non-coring well to be identified are matched with a preset boundary threshold value, and the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer of the coring well are identified, wherein the preset boundary threshold value is the natural potential relative value parameter and the resistivity ratio that need to be simultaneously satisfied by the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer.

[0100] The preset boundary threshold value can be as shown in Table 1. The RSP of the poor oil layer is greater than 0.44, and the RR value is greater than 0.5. The RSP of the natural water-flooded oil layer is less than 0.44, and the RR value is between 0 and 1. In the embodiment, the natural gamma and the deep resistivity of a formation also need to be combined to distinguish the conventional oil layer and the poor oil layer. Specifically, the natural gamma logging value also needs to be obtained when logging. The natural gamma value of the conventional oil layer is relatively low, and the deep resistivity is relatively large. The natural gamma logging value of the conventional oil layer is distributed between 7.8 and 18.5 API, with an average of 12.2 API. The deep resistivity logging value is distributed between 398.8 and 595 Ω.m, with an average of 146 Ω.m. The natural gamma value of the poor oil layer is relatively high, and the deep resistivity is relatively small. The natural gamma logging value of the poor oil layer is distributed between 19.8 and 37 API, with an average of 25 API. The deep resistivity logging value is distributed between 48 and 125 Ω.m, with an average of 73.6 Ω.m.

[0101] Embodiment three

[0102] The application further discloses a natural water-flooded oil layer identification device, which combines the natural potential relative value parameter and the resistivity ratio of the non-coring well to be identified with the preset boundary threshold value to identify the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer of the coring well. Figure 6 As shown in the figure, the device comprises a logging response characteristic parameter acquisition module 10, a first calculation module 20, a boundary threshold value generation module 30, a second calculation module 40 and an identification module 50.

[0103] ​​​The logging response characteristic parameter acquisition module 10 is used for obtaining logging response characteristic parameters of the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer of the core well of the structural adjustment reservoir, and the logging response characteristic parameters at least include the spontaneous potential SP, the deep resistivity Rt, the shallow resistivity Rs and the invasion zone resistivity Rxo.

[0104] Specifically, the logging response characteristic parameters of the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer can be directly obtained through the open hole logging, including:

[0105] The spontaneous potential SP of the conventional oil layer presents a large negative anomaly, although the invasion zone resistivity Rxo is relatively high, but there is a large positive difference between the shallow resistivity Rs curve and the deep resistivity Rt curve, the invasion zone resistivity Rxo, the shallow resistivity Rs curve and the deep resistivity Rt satisfy the following relationship: Rt> Rs>> Rxo, and the shallow resistivity Rs curve and the deep resistivity Rt are relatively large.

[0106] The spontaneous potential SP of the poor oil layer presents a large negative anomaly, the invasion zone resistivity (Rxo) is still relatively high, but still presents a low amplitude positive difference between the shallow resistivity (Rs) curve and the deep resistivity (Rt) curve; the deep resistivity and the shallow resistivity are lower than those of the conventional oil layer, and present a small positive difference between them, the invasion zone resistivity Rxo, the shallow resistivity Rs curve and the deep resistivity Rt satisfy the following relationship: Rt> Rs> Rxo.

[0107] The spontaneous potential of the natural water-flooded oil layer presents a negative anomaly, but the anomaly amplitude is relatively low compared with the conventional oil layer or the poor oil layer; the deep resistivity value Rt, the shallow resistivity value Rs and the invasion zone resistivity value Rxo are all obviously lower than those of the conventional oil layer or the poor oil layer, the deep resistivity Rt is basically close to the shallow resistivity Rs curve, and presents a low amplitude positive difference between the shallow resistivity (Rs) curve, the invasion zone resistivity Rxo, the shallow resistivity Rs curve and the deep resistivity Rt satisfy the following relationship: Rt≈ Rs> Rxo.

[0108] The formation water salinity of the water layer is high, and the conductive ability is strong, the resistivity of the water layer is less than 1 Ω.m, the deep resistivity and the shallow resistivity are slightly less than the invasion zone resistivity, and overall present an increased resistivity invasion, but the three are basically similar. The invasion zone resistivity Rxo, the shallow resistivity Rs curve and the deep resistivity Rt satisfy the following relationship: Rt≈ Rs< Rxo.

[0109] The first calculation module 20 is used for calculating the natural potential relative value parameter and the resistivity ratio value of the conventional oil layer, the poor oil layer, the natural water flooded oil layer and the water layer respectively by using the logging response characteristic parameters, wherein the natural potential relative value parameter is used for reflecting the difference of the natural potential of the conventional oil layer, the water flooded layer and the water layer at different well points, and the resistivity ratio parameter is used for reflecting the difference of the resistivity value distribution and the resistivity ratio change rule among the conventional oil layer, the poor oil layer, the water flooded layer and the water layer.

[0110] In order to quantitatively reflect the difference of the natural potential of the oil layer, the water flooded layer and the water layer at different well points, the natural potential relative value (RSP) parameter is introduced, and the expression thereof is a preset first formula:

[0111]

[0112] In the formula, RSP represents the natural potential relative value, which is dimensionless, and the value thereof is between 0 and 1, SP represents the natural potential value of an arbitrary point, mV, SPmax represents the maximum value of the natural potential of the target layer, mV, and SPmin represents the minimum value of the natural potential of the target layer, mV. max min

[0113] Since the natural potential measurement value of the oil layer is closer to the minimum value of the natural potential, and the natural potential measurement value of the water flooded layer and the water layer is closer to the maximum value of the natural potential, after the above data transformation processing, the RSP value of the oil layer is close to 1, and the RSP value of the water flooded layer and the water layer is closer to 0. The formula converts the natural potential value measured at different well points into the natural potential relative value between 0 and 1, which is dimensionless, thereby eliminating the influence of the logging instrument, the logging environment and the like on the natural potential logging response.

[0114] In addition, the inventor finds that the amplitude difference Rt / Rxo, Rs / Rxo between the deep resistivity Rt, the shallow resistivity Rs and the invasion zone resistivity Rxo is not equal among the oil layer, the poor oil layer, the water flooded layer and the water layer. The resistivity ratio parameter RR can better reflect the difference among the oil layer, the poor oil layer, the water flooded layer and the water layer by comprehensively considering the resistivity value distribution and the change rule of the resistivity ratio, and the specific calculation formula thereof is a preset second formula:

[0115]

[0116] In the formula, RR represents the resistivity relative value, which is dimensionless, Rt represents the deep resistivity of the formation, Ω.m, Rs represents the shallow resistivity of the formation, Ω.m, and Rxo represents the invasion zone resistivity of the formation, Ω.m. t s xo

[0117] ​​​​​The demarcation threshold generation module 30 is configured to obtain the demarcation threshold of the natural potential relative value parameter and the resistivity ratio value of the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer.

[0118] Based on the intersection map and data statistics of the natural potential relative value RSP and the resistivity ratio value RR of various oil and water layers, the classification limits of the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer are determined.

[0119] In combination Figure 4 As shown in the figure, the distribution ranges of the conventional oil layer, the poor oil layer, the water-flooded layer and the water layer on the intersection map of the natural potential relative value RSP and the resistivity ratio value RR are obviously different. The conventional oil layer and the poor oil layer are distributed in the upper right corner of the intersection map, although they have overlapping and intersecting parts, but there is still an obvious difference between them and the water-flooded layer, mainly reflected in that the natural potential relative value RSP of the oil layer and the poor oil layer is greater than 0.5 and 0.44 respectively, while the natural potential relative value RSP of the water-flooded layer is between 0.12 and 0.44; the resistivity ratio value RR of the oil layer and the poor oil layer is greater than 0.5, while the resistivity ratio value RR of the water-flooded layer is between 0 and 1. As for the same well, the deep resistivity value Rt of the water-flooded layer is lower than that of the poor oil layer, so it is easier to distinguish. The natural potential relative value RSP of the water layer is less than 0.12, and the resistivity ratio value RR is less than 0, both of which are relatively low and easy to identify. Table 1 shows the demarcation threshold of the natural potential relative value parameter and the resistivity ratio value of the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer.

[0120] The second calculation module 40 is configured to obtain the logging response characteristic parameters of the non-coring well to be identified, and calculate the natural potential relative value parameter and the resistivity ratio value of the non-coring well to be identified.

[0121] Specifically, the natural potential SP, the deep resistivity Rt, the shallow resistivity Rs and the invasion zone resistivity Rxo of the non-coring well to be identified are obtained; the natural potential relative value parameter is obtained by using a preset first formula, and the resistivity ratio value is obtained by using a preset second formula.

[0122] The preset first formula is as follows:

[0123]

[0124] In the formula, RSP represents the natural potential relative value, which is dimensionless and its value is between 0 and 1, SP and SP represent the natural potential value of any point, the maximum value and the minimum value of the natural potential of the target layer section respectively, and mV. max min

[0125] The preset second formula is as follows:

[0126] ​​

[0127] In the formula, RR represents a resistivity relative value, dimensionless, R t , R s , R xo respectively represent deep resistivity, shallow resistivity and invasion zone resistivity of the formation, and the unit is Ω.m.

[0128] The identification module 50 is used for matching the spontaneous potential relative value parameter and the resistivity ratio of the non-coring well to be identified with the boundary threshold value, so as to identify the oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer of the non-coring well.

[0129] The spontaneous potential relative value parameter and the resistivity ratio of the non-coring well to be identified are matched with the boundary threshold value in Table 1, so as to identify the oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer of the coring well.

[0130] According to the similarities and differences between the natural water-flooded oil layer and the poor oil layer, the boundary threshold value of the spontaneous potential relative value parameter and the resistivity ratio of the conventional oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer is calculated based on the spontaneous potential and the resistivity logging response; and then the spontaneous potential relative value parameter and the resistivity ratio of the non-coring well to be identified are matched with the boundary threshold value, so as to effectively identify the oil layer, the poor oil layer, the natural water-flooded oil layer and the water layer of the non-coring well. The present application is beneficial to accurately describing the oil-water interface morphology of the structural adjustment reservoir, can improve the calculation accuracy of the original oil geological reserves of the structural adjustment reservoir, and guides the optimization of the well perforation scheme.

[0131] Example four

[0132] Corresponding to the example two, the present application further discloses a natural water-flooded oil layer identification device, which combines Figure 7 as shown, comprising a calculation module 10' and an identification module 20', wherein:

[0133] The calculation module 10' is used for acquiring the logging response characteristic parameters of the non-coring well to be identified, and calculating the spontaneous potential relative value parameter and the resistivity ratio of the non-coring well to be identified, wherein the logging response characteristic parameters at least include the spontaneous potential, the deep resistivity, the shallow resistivity and the invasion zone resistivity.

[0134] The spontaneous potential SP, the deep resistivity Rt, the shallow resistivity Rs and the invasion zone resistivity Rxo of the non-coring well to be identified are obtained by using the open hole logging; the spontaneous potential relative value parameter is obtained by using a preset first formula, and the resistivity ratio is obtained by using a preset second formula.

[0135] The preset first formula is as follows:

[0136]

[0137] In the formula, RSP represents a natural potential relative value, dimensionless, with a value between 0 and 1, SP, SPmax and SPmin represent the natural potential value of an arbitrary point, the maximum and minimum natural potential values of a target layer, respectively, in mV. max min In the formula, RSP represents a natural potential relative value, dimensionless, with a value between 0 and 1, SP, SPmax and SPmin represent the natural potential value of an arbitrary point, the maximum and minimum natural potential values of a target layer, respectively, in mV.

[0138] A second preset formula is:

[0139]

[0140] In the formula, RR represents a resistivity relative value, dimensionless, R, Rmax and Rmin represent the deep resistivity, shallow resistivity and invasion zone resistivity of a formation, respectively, in Ω.m. t s xo In the formula, RR represents a resistivity relative value, dimensionless, R, Rmax and Rmin represent the deep resistivity, shallow resistivity and invasion zone resistivity of a formation, respectively, in Ω.m.

[0141] The identification module 20' is configured to match the natural potential relative value parameter and the resistivity ratio of the non-coring well to be identified with a preset boundary threshold value, and identify the conventional oil layer, poor oil layer, natural water-flooded oil layer and water layer of the coring well, wherein the preset boundary threshold value is the natural potential relative value parameter and the resistivity ratio that the conventional oil layer, poor oil layer, natural water-flooded oil layer and water layer need to satisfy at the same time.

[0142] The natural potential relative value parameter and the resistivity ratio of the non-coring well to be identified are matched with the boundary threshold value in Table 1, and the oil layer, poor oil layer, natural water-flooded oil layer and water layer of the coring well are identified.

[0143] In the above detailed description, various features are combined together in a single embodiment to simplify the disclosure. Such disclosure method should not be interpreted as reflecting the intention that the embodiments of the claimed subject matter require more features clearly stated in each claim. On the contrary, as reflected in the appended claims, the present application is in a state of less than all the features of the disclosed single embodiment. Therefore, the appended claims are hereby incorporated into the detailed description, in which each claim is separately a preferred embodiment of the present application.

[0144] ​​​The above description includes examples of one or more embodiments. Of course, not all possible combinations of components or methods described above can be claimed as an embodiment or employed as described above, but one of ordinary skill in the art will recognize that further modifications and permutations of various embodiments are possible. It is intended to claim all such alterations and modifications to the embodiments described herein as falling within the scope of the appended claims. Additionally, any specific unit or module described herein is intended to encompass one or more such units or modules. For example, the term "a module" is intended to mean one or more modules. Furthermore, the use of the term "or" in the claims is meant to encompass both "and" and "or" unless explicitly stated otherwise.

Claims

1. A method for identifying naturally flooded oil layers, characterized in that, Includes the following steps: Obtain logging response characteristic parameters of conventional oil layers, poor oil layers, naturally water-flooded oil layers, and water layers from core wells in structurally adjusted reservoirs. The logging response characteristic parameters include at least spontaneous potential, deep resistivity, shallow resistivity, and invasive zone resistivity. The relative values ​​of the spontaneous potential and the resistivity ratios of conventional oil layers, poor oil layers, naturally water-flooded oil layers, and water layers are calculated using the logging response characteristic parameters. The relative values ​​of the spontaneous potential are used to reflect the differences in the spontaneous potential of conventional oil layers, water-flooded layers, and water layers at different well points. The resistivity ratios are used to reflect the differences in the distribution and ratio of resistivity values ​​among conventional oil layers, poor oil layers, water-flooded layers, and water layers. By utilizing the intersection and distribution of the relative values ​​of natural potential and resistivity ratio, the boundary thresholds of conventional oil layers, poor oil layers, naturally water-flooded oil layers, and water layers in terms of relative values ​​of natural potential and resistivity ratio are obtained. Obtain the logging response characteristic parameters of the non-cored wells to be identified, and calculate the relative value of the spontaneous potential and the resistivity ratio of the non-cored wells to be identified; By matching the relative value of the natural potential and the resistivity ratio of the non-core well to be identified with the boundary threshold, the oil layer, poor oil layer, natural water-flooded oil layer and water layer of the non-core well can be identified. The relative value parameter of natural potential is calculated according to the preset first formula: In the formula: Represents the relative value of the spontaneous potential. These represent the natural potential value at any point, the maximum natural potential value of the target layer, and the minimum natural potential value, respectively. Calculate the resistivity ratio using the preset second formula: In the formula: Represents the resistivity ratio. These represent the deep resistivity, shallow resistivity, and resistivity of the intrusive zone of the formation, respectively.

2. The method for identifying naturally flooded oil layers as described in claim 1, characterized in that, Before obtaining the logging response characteristic parameters of conventional oil layers, poor oil layers, naturally water-flooded oil layers, and water layers in the core wells of structurally adjusted reservoirs, the following steps are also included: Core wells are selected from structurally adjusted reservoirs. These core wells include naturally water-flooded layers. Based on the core display characteristics, conventional oil layers, poor oil layers, naturally water-flooded oil layers, and water layers are identified.

3. The method for identifying naturally flooded oil layers as described in claim 1 or 2, characterized in that, The calculation of the relative natural potential and resistivity ratio of the non-cored wells to be identified includes: The spontaneous potential, deep resistivity, shallow resistivity, and intrusion zone resistivity of the non-coring well to be identified are obtained; The relative value of natural potential is obtained using the first preset formula, and the resistivity ratio is obtained using the second preset formula.

4. The method for identifying naturally flooded oil layers as described in claim 1 or 2, characterized in that, By matching the relative value of the natural potential and the resistivity ratio of the non-cored well to the boundary threshold, the oil layer, poor oil layer, naturally water-flooded oil layer and water layer of the cored well can be identified. It also includes the need to combine natural gamma and formation deep resistivity to distinguish between conventional oil layers and poor oil layers.

5. A method for identifying naturally flooded oil layers, characterized in that, Includes the following steps: Obtain the logging response characteristic parameters of the non-cored well to be identified, and calculate the relative value of the spontaneous potential and the resistivity ratio of the non-cored well to be identified. The logging response characteristic parameters include at least spontaneous potential, deep resistivity, shallow resistivity, and intrusion zone resistivity. By matching the natural potential relative value parameter and resistivity ratio of the non-core well to be identified with a preset boundary threshold, the conventional oil layer, poor oil layer, natural water-flooded oil layer and water layer of the core well can be identified. The preset boundary threshold is the natural potential relative value parameter and resistivity ratio that the conventional oil layer, poor oil layer, natural water-flooded oil layer and water layer must simultaneously satisfy. The relative value parameter of natural potential is obtained using a preset first formula: In the formula: Represents the relative value of the spontaneous potential. These represent the natural potential value at any point, the maximum natural potential value of the target layer, and the minimum natural potential value, respectively. The resistivity ratio is obtained using the preset second formula: In the formula: Represents the resistivity ratio. These represent the deep resistivity, shallow resistivity, and resistivity of the intrusive zone of the formation, respectively.

6. A device for identifying naturally flooded oil layers, characterized in that, It includes a well logging response characteristic parameter acquisition module, a first calculation module, a boundary threshold generation module, a second calculation module, and an identification module, wherein: The logging response characteristic parameter acquisition module is used to obtain the logging response characteristic parameters of conventional oil layers, poor oil layers, naturally water-flooded oil layers and water layers in the core well of the structurally adjusted reservoir. The logging response characteristic parameters include at least spontaneous potential, deep resistivity, shallow resistivity and intrusion zone resistivity. The first calculation module is used to calculate the relative value of the natural potential and the resistivity ratio of the conventional oil layer, poor oil layer, naturally water-flooded oil layer and water layer using the well logging response characteristic parameters. The relative value of the natural potential is used to reflect the difference in natural potential between the conventional oil layer, water-flooded layer and water layer at different well points. The resistivity ratio parameter is used to reflect the differences in the distribution and ratio of resistivity values ​​among the conventional oil layer, poor oil layer, water-flooded layer and water layer. The boundary threshold generation module is used to obtain the boundary thresholds of conventional oil layers, poor oil layers, naturally flooded oil layers, and water layers in terms of the relative value of natural potential and the resistivity ratio by utilizing the intersection distribution of the relative value of natural potential and the resistivity ratio. The second calculation module is used to obtain the logging response characteristic parameters of the non-cored well to be identified, and to calculate the relative value of the spontaneous potential and the resistivity ratio of the non-cored well to be identified. The identification module is used to match the relative value of the natural potential and the resistivity ratio of the non-core well to be identified with the boundary threshold to identify the oil layer, poor oil layer, natural water-flooded oil layer and water layer of the non-core well. The relative value parameter of natural potential is calculated according to the preset first formula: In the formula: Represents the relative value of the spontaneous potential. These represent the natural potential value at any point, the maximum natural potential value of the target layer, and the minimum natural potential value, respectively. Calculate the resistivity ratio using the preset second formula: In the formula: Represents the resistivity ratio. These represent the deep resistivity, shallow resistivity, and resistivity of the intrusive zone of the formation, respectively.

7. A device for identifying naturally flooded oil layers, characterized in that, It includes a calculation module and a recognition module, among which: The calculation module is used to obtain the logging response characteristic parameters of the non-cored well to be identified, and to calculate the relative value of the spontaneous potential and the resistivity ratio of the non-cored well to be identified. The logging response characteristic parameters include at least spontaneous potential, deep resistivity, shallow resistivity, and intrusion zone resistivity. The identification module is used to match the relative intrinsic potential (TIP) parameter and resistivity ratio of the non-cored well to a preset boundary threshold to identify the conventional oil layer, poor oil layer, naturally water-flooded oil layer, and water layer of the cored well. The preset boundary threshold is the relative intrinsic potential parameter and resistivity ratio that the conventional oil layer, poor oil layer, naturally water-flooded oil layer, and water layer must simultaneously satisfy. The relative value parameter of natural potential is obtained using a preset first formula: In the formula: Represents the relative value of the spontaneous potential. These represent the natural potential value at any point, the maximum natural potential value of the target layer, and the minimum natural potential value, respectively. The resistivity ratio is obtained using the preset second formula: In the formula: Represents the resistivity ratio. These represent the deep resistivity, shallow resistivity, and resistivity of the intrusive zone of the formation, respectively.

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