Well logging evaluation method and device for identifying gas-water properties of unconsolidated sandstone reservoir and program product
By using the neutron and acoustic values of mudstone sections in loose sandstone reservoirs as a benchmark, and combining the deep and shallow resistivity ratios, reservoir quality and fluid indicator factors are calculated, solving the problem of difficult gas-water property identification in existing technologies and achieving high-precision gas-water layer identification.
Patent Information
- Application Number
- CN202410986550.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-23
- Publication Date
- 2026-01-23
AI Technical Summary
In loose sandstone reservoirs, existing technologies are insufficient to effectively identify gas and water properties. In particular, resistivity logging is affected by low resolution and heterogeneity, making it difficult to identify gas layers. When edge water advances and gas reservoir pressure decreases, resistivity logging data is insufficient to determine fluid properties.
Using the neutron and acoustic values of the mudstone section as a benchmark, the reservoir characteristics and fluid properties are determined by calculating the difference between the neutron and acoustic values of the reservoir section and the mudstone section, supplemented by the deep-shallow resistivity ratio. This includes determining the neutron benchmark value and the acoustic time difference benchmark value, calculating the reservoir quality factor and the fluid indicator factor, classifying the lithological purity by combining the mud content, and identifying the fluid.
It enables accurate identification of gas and water properties in loose sandstone reservoirs, avoids misjudgments caused by differences in logging curves between different wells, and improves the accuracy and reliability of gas and water layer identification.
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Figure CN121382178A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of oil and gas exploration and development, and particularly relates to a logging evaluation method, device and program product for identifying gas-water properties of a loose sandstone reservoir. BACKGROUND
[0002] The Quaternary stratum of the Qaidam Basin has a relatively shallow burial depth and is in the early stage of diagenesis, which is a typical representative of weak diagenesis. This geological background leads to the formation of loose sandstone and mudstone reservoirs in the Sanhu area. The loose sandstone and mudstone reservoir is a complex geological system. The sandstone and mudstone have a relatively large porosity. The area where the reservoir is located has a relatively high content of mud and is interlaced with iron and carbon minerals and other substances, resulting in a low resistivity and making the logging response not obvious. This makes it difficult to identify gas layers and brings great challenges to the development and production of gas fields. In the logging interpretation of oil and gas reservoirs, the use of resistivity logging to divide the fluid properties of the reservoir is the most common and effective method. Generally, when the reservoir is full of oil and gas, the resistivity is obviously high. When the reservoir is a water layer, the resistivity is low. The resistivity logging is affected by the low resolution. In the case of obvious reservoir heterogeneity, the influence of thin reservoirs and lithology on resistivity cannot be well reflected, which may cause certain difficulties in identifying the fluid by using resistivity.
[0003] Due to the special physical properties of natural gas, the porosity logging data changes significantly, such as the decrease of the density logging value and the increase of the acoustic logging value. Sometimes, the cycle jump feature appears in some well sections. Due to the existence of the excavation effect, the neutron logging value is obviously small in the gas layer. These features provide a good basis for identifying the gas layer. SUMMARY
[0004] In order to overcome the defects of the prior art, the application uses the neutron and acoustic values of the mudstone section as the reference values, calculates the difference between the neutron and acoustic values of the reservoir section and the mudstone section, and then uses the deep and shallow resistivity ratio to determine the reservoir characteristics and fluid properties, so as to divide the properties of the loose sandstone reservoir and provide a basis for the next test layer selection.
[0005] The first object of the application is to provide a logging evaluation method for identifying the gas-water properties of a loose sandstone reservoir, which comprises the following steps:
[0006] determining the mudstone section based on the wellbore rule, gamma value, acoustic value and resistivity;
[0007] determining the neutron reference value and the acoustic time difference reference value of the mudstone section;
[0008] a difference between the interval transit time value of the reservoir section and an interval transit time reference value is calculated as a reservoir quality factor;
[0009] a difference between the neutron value of the reservoir section and a neutron reference value is calculated as a fluid indication factor;
[0010] a reservoir lithology purity is classified based on shale content;
[0011] a product of the fluid indication factor and a deep-to-shallow resistivity ratio under different lithology purities is calculated as a fluid identification factor;
[0012] reservoir fluid classification under different lithology purities is performed based on the reservoir quality factor and the fluid identification factor.
[0013] Further, the neutron reference value and the interval transit time reference value of the shale section are determined, comprising:
[0014] on a well logging curve display, the neutron logging curve and the interval transit time logging curve of the shale section are adjusted to coincide;
[0015] the neutron value and the interval transit time value at the coincidence of the shale section are determined as the neutron reference value and the interval transit time reference value respectively.
[0016] Further, the reservoir lithology purity is classified based on shale content, comprising:
[0017] the reservoir with shale content ≤25% is classified as a relatively pure lithology reservoir;
[0018] the reservoir with shale content >25% is classified as a relatively poor lithology reservoir.
[0019] Further, when the reservoir is a relatively pure lithology reservoir, the calculation formula of the fluid identification factor is as follows:
[0020] I gw =ΔCNL*(R 深 / R 浅 )
[0021] Wherein, I gw is the fluid identification factor, ΔCNL is the fluid indication factor, R 深 is the deep resistivity, and R 浅 is the shallow resistivity.
[0022] Further, the reservoir fluid classification under different lithology purities is performed based on the reservoir quality factor and the fluid identification factor, comprising:
[0023] When the reservoir is a relatively pure lithology reservoir,
[0024] If ΔAC≥21us / m, and I gw ≤-5, the reservoir is identified as a gas reservoir;
[0025] if ΔAC≥21us / m and -1.5≤I gw >-5, the reservoir is identified as a gas-water layer;
[0026] if ΔAC≥21us / m and -1.5≤I gw >-1.5, the reservoir is identified as a water-bearing gas layer or a water layer.
[0027] Further, when the reservoir is a poor lithology reservoir, the calculation formula of the fluid identification factor is as follows:
[0028] I gw = ΔCNL*(R 深 / R 浅 ) / ΔAC*100
[0029] wherein ΔAC is a reservoir quality factor.
[0030] Further, based on the reservoir quality factor and the fluid identification factor, the reservoir fluid of different lithology purity is divided, including:
[0031] When the reservoir is a poor lithology reservoir,
[0032] if ΔAC<21us / m and I gw ≤-1, the reservoir is identified as a poor gas layer;
[0033] if ΔAC<21us / m and I gw >-1, the reservoir is identified as a gas-bearing layer or a dry layer.
[0034] A second object of the present application is to provide a logging evaluation system for identifying gas-water properties of a loose sandstone reservoir, comprising:
[0035] A mudstone determination module is configured to determine a mudstone section based on a borehole rule, a gamma value, a sonic wave, and a resistivity.
[0036] A reference determination module is configured to determine a neutron reference value and a sonic time difference reference value of the mudstone section.
[0037] A quality factor module is configured to calculate a difference between a sonic time difference value of the reservoir section and the sonic time difference reference value as a reservoir quality factor.
[0038] An indication factor module is configured to calculate a difference between a neutron value of the reservoir section and the neutron reference value as a fluid indication factor.
[0039] A purity division module is configured to divide the lithology purity of the reservoir based on the shale content.
[0040] An identification factor module is configured to calculate a product of the fluid indication factor and a deep-shallow resistivity ratio of the reservoir under different lithology purity as a fluid identification factor.
[0041] A fluid classification module is used to classify reservoir fluids of different lithology purity based on reservoir quality factor and fluid identification factor.
[0042] A third object of the present application is to provide an electronic device comprising a memory and a processor, the memory storing a computer program or instructions, the computer program or instructions being executed by the processor to implement at least the method described above.
[0043] A fourth object of the present application is to provide a computer readable storage medium storing a computer program or instructions, the computer program or instructions being executed by a processor to implement at least the method described above.
[0044] A fifth object of the present application is to provide a computer program product stored in a computer readable storage medium, the computer program product being executed by a processor to implement at least the method described above.
[0045] Technical effects and advantages of the present application:
[0046] In view of the characteristics of loose sandstone, such as high porosity, high permeability, high salinity, high mud content and low resistance, and the differences in logging data of different wells, it is difficult to identify the fluid properties by using conventional logging data. The present application uses the neutron and acoustic values of the mudstone section as the reference value, and uses the difference between the neutron and acoustic values of the reservoir section and the mudstone section, supplemented by the relationship of resistivity, to highlight the reservoir quality and fluid characteristics, and then to judge the reservoir characteristics and fluid properties. This can not only realize the identification of reservoir fluid properties, but also avoid the misjudgment of fluid properties caused by the differences in logging curves between different wells.
[0047] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be realized and obtained by the structures indicated in the specification, claims and drawings. BRIEF DESCRIPTION OF DRAWINGS
[0048] Figure 1 Flow chart of a logging evaluation method for identifying gas and water properties of loose sandstone reservoirs according to the present application;
[0049] Figure 2 Resistivity and acoustic crossplot of 9 test wells;
[0050] Figure 3 Resistivity and neutron crossplot of 9 test wells;
[0051] Figure 4 Reservoir quality factor boxplot of 9 test wells;
[0052] Figure 5The fluid identification factor box chart for 9 test wells;
[0053] Figure 6 The loose sandstone fluid identification chart of the embodiment of the application;
[0054] Figure 7 The production profile test result chart of the embodiment of the application. DETAILED DESCRIPTION
[0055] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the application.
[0056] The design idea of the application is as follows: acoustic logging is mainly used to determine rock porosity, that is, the greater the acoustic time difference value, the greater the porosity, and thus, under the condition of the same lithology, the acoustic logging value can reflect the reservoir quality. In addition to being used to calculate porosity, the compensated neutron logging is more important for identifying gas and water properties; the neutron logging value is small in a gas layer and large in a high salinity water layer, and thus, the neutron value can be used to divide the gas and water layers. Research shows that the reservoir logging characteristics are closely related to the surrounding rock (adjacent mudstone), that is, when the surrounding rock (adjacent mudstone) is relatively dense, the resistivity, porosity and other curves of the adjacent reservoir also change to a certain extent, and thus, the change made in the application according to the relationship between the acoustic logging, neutron logging and the surrounding rock (adjacent mudstone) can further highlight the reservoir and fluid characteristics, and can eliminate the curve quality problems between different wells caused by various factors. Meanwhile, the difference between the deep and shallow resistivity logging can also reflect the reservoir fluid, that is, when the reservoir is a gas layer, the deep and shallow resistivity ratio is generally greater than or equal to 1; when the reservoir contains water, the deep and shallow resistivity ratio is less than 1, and the more water contained, the smaller the ratio. Therefore, the product of the difference between the neutron and the surrounding rock (adjacent mudstone) and the resistivity ratio can further obtain the reservoir fluid occurrence.
[0057] In actual application (taking the neutron and acoustic logging data as an example), first, a mudstone section with a large natural gamma value is selected (the wellbore of this well section is required to be regular, the acoustic logging does not jump, and the resistivity presents a low value), the scales of the neutron and acoustic logging data are adjusted, the neutron and acoustic logging curves in the mudstone section are ensured to coincide, and the neutron and acoustic values of the coinciding section are taken as the reference values; thereafter, three parameters are calculated: 1) the difference between the acoustic logging values of the reservoir section and the mudstone is calculated, and the greater the difference, the better the reservoir physical property; 2) the difference between the neutron values of the reservoir section and the mudstone is calculated, and the smaller the difference, the better the gas content of the reservoir; and 3) the product of the difference calculated in 2) and the deep and shallow resistivity ratio is used to determine the reservoir fluid property.
[0058] When making a final judgment on the properties of reservoir fluids, the following assumptions must be followed: strata with relatively pure lithology develop gas layers, gas-water co-layers, and water layers, but do not develop poor gas layers or gas-bearing layers; while strata with high mud content and impure lithology develop only poor gas layers and gas-bearing layers, but do not develop gas-water layers.
[0059] Firstly, specifically, such as Figure 1 As shown, this application provides a well logging evaluation method for identifying the gas-water properties of loose sandstone reservoirs, including:
[0060] The mudstone section was determined based on wellbore regularity, gamma value, sonic wave, and resistivity.
[0061] Determine the neutron reference value and acoustic transit time reference value for the mudstone section;
[0062] The difference between the acoustic transit time value of the reservoir section and the acoustic transit time reference value is calculated as the reservoir quality factor.
[0063] The difference between the neutron value of the reservoir section and the neutron reference value is calculated as a fluid indicator factor;
[0064] Reservoir lithological purity is determined based on clay content;
[0065] The product of the reservoir fluid indicator factor and the deep-shallow resistivity ratio under different lithological purities is calculated as the fluid identification factor.
[0066] Reservoir fluid classification based on reservoir quality factors and fluid identification factors for different lithological purities.
[0067] Specifically, taking nine test wells in a certain production block as an example, conventional logging combinations have low accuracy in identifying gas and water layers, such as... Figure 2 , Figure 3 As shown, conventional logging has a weak ability to distinguish between gas and water layers. This indicates that resistivity is not a crucial parameter for gas-water identification, and neutrons also fail to effectively separate gas and water layers. This application uses the difference between the acoustic transit time value of the reservoir section and the acoustic transit time reference value as a reservoir quality factor, which yields the following results: Figure 3 The reservoir quality factor box plot shown is composed of... Figure 3 As can be seen, the larger the acoustic difference, the better the reservoir quality. Therefore, the order of reservoir quality from best to worst is: gas layer > gas-water layer > gas-water co-layer > poor gas layer > gas-bearing layer. Furthermore, this application uses the obtained fluid indicator factors to create a box plot, such as... Figure 4 As shown, it is clear that the gas layer and the aquifer are significantly different, and the reservoir fluid properties can be directly classified based on the value of the fluid indicator factor.
[0068] In some embodiments of this application, determining the neutron reference value and the acoustic transit time reference value for the mudstone section includes:
[0069] On the well logging curve display, the neutron logging curve and the acoustic time difference logging curve of the mudstone section are adjusted to coincide;
[0070] The neutron value and the acoustic time difference value at the coincidence of the mudstone section are determined as the neutron reference value and the acoustic time difference reference value respectively.
[0071] In some embodiments of the present application, the reservoir lithology purity is divided based on the shale content, including:
[0072] The reservoir with shale content ≤25% is divided into a relatively pure lithology reservoir;
[0073] The reservoir with shale content >25% is divided into a poor lithology reservoir.
[0074] In some embodiments of the present application, when the reservoir is a relatively pure lithology reservoir, the calculation formula of the fluid identification factor is as follows:
[0075] I gw =ΔCNL*(R 深 / R 浅 )
[0076] Wherein, I gw is the fluid identification factor, ΔCNL is the fluid indication factor, R 深 is the deep resistivity, and R 浅 is the shallow resistivity. The multiplication of the deep and shallow resistivity is because the deep and shallow resistivity ratio is generally greater than or equal to 1, while the deep and shallow resistivity ratio is less than 1 after the reservoir contains water, the more water, the smaller the ratio, therefore, the difference between the neutron and the surrounding rock (adjacent mudstone) and the resistivity ratio are multiplied, which can further obtain the fluid occurrence condition of the reservoir.
[0077] In some embodiments of the present application, the reservoir fluid of different lithology purity is divided based on the reservoir quality factor and the fluid identification factor, including:
[0078] When the reservoir is a relatively pure lithology reservoir,
[0079] If ΔAC≥21us / m, and I gw ≤-5, the reservoir is identified as a gas layer;
[0080] If ΔAC≥21us / m, and-1.5≤I gw >-5, the reservoir is identified as a gas-water layer;
[0081] If ΔAC≥21us / m, and I gw >-1.5, the reservoir is identified as a water-bearing gas layer or a water layer.
[0082] In some embodiments of the present application, when the reservoir is a poor lithology reservoir, the calculation formula of the fluid identification factor is as follows:
[0083] Igw = ΔCNL * (R 深 / R 浅 ) / ΔAC * 100
[0084] Wherein, ΔAC is reservoir quality factor, dividing by ΔAC is approximately to make mud content caused by sound wave larger correction, and dividing by coefficient 100 is to make the fluid identification factor value of poor lithology reservoir and pure lithology reservoir in one order of magnitude.
[0085] In some embodiments of the present application, the reservoir fluid classification of different lithology purity based on reservoir quality factor and fluid identification factor includes:
[0086] When the reservoir is poor lithology reservoir,
[0087] If ΔAC < 21 us / m, and I gw ≤-1, the reservoir is identified as poor gas layer;
[0088] If ΔAC < 21 us / m, and I gw >-1, the reservoir is identified as gas-bearing layer or dry layer.
[0089] In a second aspect, the present application provides a logging evaluation system for identifying gas and water properties of unconsolidated sandstone reservoir, comprising:
[0090] The mudstone determination module is used for determining the mudstone section based on the borehole rule, gamma value, acoustic wave and resistivity;
[0091] The reference determination module is used for determining the neutron reference value and acoustic time difference reference value of the mudstone section;
[0092] The quality factor module is used for calculating the difference between the acoustic time difference value of the reservoir section and the acoustic time difference reference value as the reservoir quality factor;
[0093] The indicator factor module is used for calculating the difference between the neutron value of the reservoir section and the neutron reference value as the fluid indicator factor;
[0094] The purity division module is used for dividing the lithology purity of the reservoir based on the mud content;
[0095] The identification factor module is used for calculating the product of the reservoir fluid indicator factor and the deep and shallow resistivity ratio under different lithology purity as the fluid identification factor;
[0096] The fluid classification module is used for classifying the reservoir fluid of different lithology purity based on the reservoir quality factor and the fluid identification factor.
[0097] In a third aspect, the present application provides an electronic device, comprising a memory and a processor, the memory stores computer programs or instructions, and the computer programs or instructions are executed by the processor to at least implement the above-mentioned method.
[0098] In a fourth aspect, the present application provides a computer readable storage medium, wherein the computer readable storage medium stores a computer program or instructions, and the computer program or instructions, when executed by a processor, are used to implement at least the method described above.
[0099] In a fifth aspect, the present application provides a computer program product stored in a computer readable storage medium, and the computer program product, when executed by a processor, is used to implement at least the method described above.
[0100] In order to better illustrate the present application, the following examples are provided.
[0101] Examples
[0102] Taking a certain unconsolidated sandstone well as an example, the fluid identification chart of the well is shown in FIG. 1, from left to right, Figure 6 Figure 6 The first track is a depth track, which shows the depth of the well; the second track is a lithology indication track, which lists the natural gamma, natural potential and caliper curves; the third track is a porosity track, which shows the neutron, acoustic and density curves, the short dashed line is the density curve, the long dashed line is the neutron curve, and the solid line is the acoustic interval travel time curve; the fourth track is a resistivity track, which lists the deep and shallow resistivity curves; the fifth track is a lithology combination track, which lists the logging lithology and clearly identifies the standard lithology as mudstone; the sixth track is a perforation track, which lists the perforated well section; the seventh track is a reservoir quality track, which lists the reservoir quality factor calculated by the present application and the reservoir quality limit value (21us / m); the eighth track is a fluid identification track, which lists the fluid identification factor calculated by the present application and the gas-water limit value (gas line-5, water line-1); and the ninth track is an interpretation conclusion track, which shows the fluid division result based on the reservoir quality factor and the fluid identification factor.
[0103] First, based on the wellbore rules, gamma value, acoustic wave and resistivity, the mudstone section is determined, Figure 6 In the second track, in the 585.0-592.0m well section, the natural gamma is about 95API, the neutron and acoustic curves are stable, and the mudstone baseline condition is met.
[0104] Then in Figure 6 The third track, the neutron logging curve and the acoustic interval travel time curve of the mudstone section are adjusted to coincide; the neutron value and the acoustic interval travel time value at the coincidence position of the mudstone section are determined as the neutron reference value and the acoustic interval travel time reference value, respectively.
[0105] Then the difference between the acoustic interval travel time value of the reservoir section and the acoustic interval travel time reference value is calculated as the reservoir quality factor, and the reservoir quality factor equal to 21us / m is used as the division limit to obtain Figure 6 The reservoir quality line (solid line) and the reservoir limit value (dashed line) of the seventh track.
[0106] The difference between the neutron value of the reservoir section and the neutron reference value is calculated as a fluid indicator; the reservoir lithology purity is divided based on the shale content; the product of the reservoir fluid indicator and the deep-shallow resistivity ratio corresponding to the lithology purity is calculated as a fluid identification factor, and the fluid identification factor equal to-5 is taken as the gas line (short dashed line) and the fluid identification factor equal to-1 is taken as the water line, to obtain Figure 6 The fluid identification line of the eighth track.
[0107] Finally, the reservoir fluid is divided based on the reservoir quality factor of the seventh track and the fluid identification factor of the eighth track, to obtain the interpretation conclusion track of the ninth track:
[0108] As shown in Figure 7 the well production profile test result, the 570.4-575m well section of the well is the main gas and water producing section of the well, Figure 6 The reservoir quality factor in the 570.4-575m well section is mostly greater than 21us / m, which is in the limit range of good physical property and high quality, and the fluid identification factor line value is obviously greater than the gas line value, and it is analyzed that the water content of this section is obvious, and it is interpreted as a gas and water layer. The reservoir quality curve in the 575-582m well section is less than the high-quality reservoir quality line value, and it is analyzed that the reservoir physical property of this section is poor, and the probability of water production is low, and this section is interpreted as a gas layer.
[0109] Figure 7 The 593.0-594.1m well section is the second main gas producing section, Figure 6 The reservoir quality curve of this well section calculated by the present application is mostly greater than 21us / m, which is in the limit range of good physical property and high quality, and the fluid identification line value is obviously less than the gas line value, and it is interpreted as a gas layer.
[0110] Figure 7 The 595.2-596.1m well section has a gas production contribution rate of only 1.3%, Figure 6 The reservoir quality curve of this well section calculated by the present application is less than the high-quality reservoir quality line value, and it is analyzed that the reservoir physical property of this section is poor, and the probability of water production is low, and this section is interpreted as a gas layer.
[0111] Figure 7 The 599.9-601.1m well section has a gas production contribution rate of only 2.6%, Figure 6 The reservoir quality curve of this well section calculated by the present application is less than 21us / m, and the value is extremely low, the logging data analysis shows that the lithology is dense, the logging lithology is calcareous siltstone, the physical property is poor, and it is interpreted as a gas layer.
[0112] Figure 7Although the production test contribution rate of the 602.7-610.6 m well section is low, only 3.9%, the well logging response analysis shows that the sand burial phenomenon may exist in the section, resulting in low output. Figure 6 The reservoir quality and fluid identification curve values of the well section are calculated in the application, and the section is interpreted in three sections. The reservoir quality of the 602.7-604.6 m well section is good as a whole, the fluid identification curve is within the gas line, and considering the natural gamma curve, it is interpreted as a poor gas layer; the reservoir quality value of the 604.6-607.2 m well section is high, but the fluid identification curve value is generally between the gas line and the water line, and considering the lithology comprehensive analysis, it is interpreted as a gas-water layer; the reservoir quality of the 607.2-610.6 m curve is relatively low as a whole, and the fluid identification line value is generally greater than the gas line value, considering the lithology factor, the layer is interpreted as a gas-bearing layer.
[0113] Figure 6 The natural gamma value of the 612.6-616 m well section is high, the lithology is argillaceous siltstone, the calculated reservoir quality factor curve is less than the high-quality reservoir quality line value, it is analyzed that the reservoir physical property of the section is poor, the fluid identification line value is obviously greater than the gas line value, according to the identification standard, the section is interpreted as a gas-bearing layer.
[0114] In summary, in view of the characteristics of loose sandstone, high porosity, high permeability, high salinity, high argillaceous content, low resistance and the existence of certain differences in logging data of different wells, it is difficult to identify the fluid properties by using conventional logging data. The application uses the neutron and acoustic values of the mudstone section as the reference value, through the difference between the reservoir section and the mudstone section in neutron and acoustic values, and supplemented by the relationship of resistivity, the reservoir quality and fluid characteristics are highlighted, and then the reservoir characteristics and fluid properties are judged, which can realize the identification of reservoir fluid properties, and avoid the misjudgment of fluid properties caused by the differences between logging curves of different wells.
[0115] Finally, it should be noted that: the above only describes the preferred embodiments of the application and is not intended to limit the application. Although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to some technical features, as long as they are within the spirit and principles of the application. Any modification, equivalent replacement, improvement, etc. made shall be included in the protection scope of the application.
Claims
1. A method of log evaluation for identifying gas-water properties of a loose sand reservoir, characterized by, The method comprises the following steps: determining a mudstone section based on borehole rules, gamma value, acoustic wave and resistivity; determining a neutron reference value and an acoustic travel time reference value of the mudstone section; calculating a difference between an acoustic travel time value of a reservoir section and the acoustic travel time reference value as a reservoir quality factor; calculating a difference between a neutron value of the reservoir section and the neutron reference value as a fluid indication factor; dividing reservoir lithology purity based on shale content; calculating a product of the reservoir fluid indication factor and a deep-shallow resistivity ratio under different lithology purity as a fluid identification factor; dividing reservoir fluid of different lithology purity based on the reservoir quality factor and the fluid identification factor.
2. The method of evaluating gas-water properties of unconsolidated sandstone reservoirs according to claim 1, wherein, The method for determining the neutron reference value and the acoustic travel time reference value of the mudstone section comprises the following steps: adjusting a neutron logging curve and an acoustic travel time logging curve of the mudstone section to coincide on a logging curve display diagram; determining the neutron value and the acoustic travel time value at the coincidence of the mudstone section as the neutron reference value and the acoustic travel time reference value respectively.
3. The method of claim 1, wherein the method further comprises: The method for dividing reservoir lithology purity based on shale content comprises the following steps: dividing reservoirs with shale content ≤25% into relatively pure lithology reservoirs; dividing reservoirs with shale content >25% into relatively poor lithology reservoirs.
4. The method of claim 3, wherein the method further comprises: When the reservoir is a relatively pure lithology reservoir, the calculation formula of the fluid identification factor is as follows: I gw = ΔCNL * (R 深 / R 浅 ) where I gw is the fluid identification factor, ΔCNL is the fluid indication factor, R 深 is the deep resistivity, R 浅 is the shallow resistivity.
5. The method of evaluating gas-water properties of unconsolidated sandstone reservoirs by well logging according to claim 4, characterized in that, The method for dividing reservoir fluid of different lithology purity based on the reservoir quality factor and the fluid identification factor comprises the following steps: When the reservoir is a relatively pure lithology reservoir, If ΔAC≥ 21 us / m, and I gw ≤ -5, the reservoir is identified as a gas reservoir. If ΔAC≥21 us / m, and -1.5≤I gw > -5, the reservoir is identified as a gas-water layer. If ΔAC≥ 21 us / m, and I gw > -1.5, the reservoir is identified as a water-bearing gas reservoir or a water layer.
6. The method of evaluating gas-water properties of unconsolidated sandstone reservoirs by well logging according to claim 3, wherein, When the reservoir is a relatively poor lithology reservoir, the calculation formula of the fluid identification factor is as follows: I gw = ΔCNL * (R 深 / R 浅 ) / ΔAC*100 wherein, ΔAC is the reservoir quality factor.
7. The method of evaluating gas-water properties of unconsolidated sandstone reservoirs by well logging according to claim 6, characterized in that, The method for dividing reservoir fluid of different lithology purity based on the reservoir quality factor and the fluid identification factor comprises the following steps: When the reservoir is a relatively poor lithology reservoir, If ΔAC < 21 us / m, and I gw ≤ -1, the reservoir is identified as a poor gas reservoir. If ΔAC < 21 us / m, and I gw > -1, the reservoir is identified as a gas-bearing or dry reservoir.
8. A well-logging evaluation system for identifying gas-water properties of a loose sand reservoir, characterized by, The method comprises the following steps: a mudstone determination module for determining a mudstone section based on borehole rules, gamma value, acoustic wave and resistivity; a reference determination module for determining a neutron reference value and an acoustic travel time reference value of the mudstone section; a quality factor module for calculating a difference between an acoustic travel time value of a reservoir section and the acoustic travel time reference value as a reservoir quality factor; an indication factor module for calculating a difference between a neutron value of the reservoir section and the neutron reference value as a fluid indication factor; a purity division module for dividing reservoir lithology purity based on shale content; an identification factor module for calculating a product of the reservoir fluid indication factor and a deep-shallow resistivity ratio under different lithology purity as a fluid identification factor; a fluid division module for dividing reservoir fluid of different lithology purity based on the reservoir quality factor and the fluid identification factor.
9. An electronic device comprising a memory and a processor, characterized in that The memory stores computer programs or instructions, which are executed by the processor to at least implement the method of any one of claims 1-7.
10. A computer-readable storage medium, characterized in that, The computer readable storage medium stores computer programs or instructions, which are executed by the processor to at least implement the method of any one of claims 1-7.
11. A computer program product stored in a computer readable storage medium, characterized in that, The computer program product is executed by the processor to at least implement the method of any one of claims 1-7.