CN110644978B - Quantitative evaluation method for filling strength and dissipation degree of tight gas reservoir - Google Patents
Quantitative evaluation method for filling strength and dissipation degree of tight gas reservoir Download PDFInfo
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Abstract
The invention provides a quantitative evaluation method for filling strength and dissipation degree of a dense gas reservoir, which comprises the following specific steps: 1) Establishing a relation curve of reservoir permeability and irreducible water saturation, and selecting a core sample in a permeability range according to a permeability distribution range of a tight gas reservoir; 2) Collecting an electrical logging curve and an explanation result of the gas well in the research range, extracting the physical property of the target gas reservoir and the corresponding water saturation, and fitting a relation curve; 3) Qualitatively and quantitatively analyzing the filling degree; 4) Qualitatively and quantitatively analyzing the loss degree; 5) And (4) overall evaluation of filling strength and dissipation degree of the gas reservoir. The invention does not need to collect a large amount of rock samples and perform experimental analysis, and only needs to analyze the well logging interpretation of the completed well. The method has universality for the dense gas reservoir, can give quantitative evaluation results, and is beneficial to the comparative analysis among the gas reservoirs of the same type.
Description
Technical Field
The invention relates to the field of natural gas development, in particular to a method for simply and quickly realizing quantitative evaluation of filling degree and dissipation degree of a compact gas reservoir through logging parameters, which is suitable for compact gas reservoir formation condition evaluation and formation water cause analysis, and particularly relates to a quantitative evaluation method for filling strength and dissipation degree of the compact gas reservoir.
Background
The compact gas reservoir has poor physical properties, complex reservoir formation control factors and more water produced by a gas well in the gas reservoir development process. In order to improve the development effect and accurately evaluate the filling strength and the dissipation degree of the tight gas reservoir, the basis for judging the formation water cause is one of the important contents of gas reservoir evaluation. At present, evaluation on the reservoir filling strength and the loss degree depends on a large number of experiments and researches such as hydrocarbon source rock analysis, cover layer sealing evaluation, basin simulation and the like, and the method is large in workload, long in period and high in cost. In addition, a large amount of hydrocarbon source rock and reservoir samples need to be collected, and the samples which can be provided in most regions are limited and difficult to accurately evaluate. At present, no effective method capable of rapidly and quantitatively evaluating filling strength and dissipation degree of gas reservoir formation exists at home and abroad.
Disclosure of Invention
The invention provides a quantitative evaluation method for filling strength and dissipation degree of a compact gas reservoir, aiming at solving the problems of large workload, long period and high cost of a large number of experiments and mathematical calculations such as a large number of hydrocarbon source rock analyses, reservoir storage condition evaluation, basin simulation and the like in the original gas reservoir evaluation process. Based on the rule, the filling intensity and the storage condition of the compact gas reservoir can be judged through analyzing the relation between the existing physical property and the gas content of the gas reservoir. The invention does not need to collect a large amount of rock samples and perform experimental analysis, and only needs to analyze the well logging explanation of the existing well. The method has universality for the dense gas reservoir, can give quantitative evaluation results, and is beneficial to the comparative analysis among the gas reservoirs of the same type.
The technical scheme adopted by the invention is as follows:
a quantitative evaluation method for filling strength and dissipation degree of a dense gas reservoir comprises the following specific steps:
1) Establishing a relation curve of reservoir permeability and irreducible water saturation, and selecting a core sample in a permeability range according to a permeability distribution range of a tight gas reservoir;
2) Collecting an electrical logging curve and an explanation result of the gas well in the research range, extracting the physical property of the target gas reservoir and the corresponding water saturation, and fitting a relation curve;
3) Qualitatively and quantitatively analyzing the filling degree;
4) Qualitatively and quantitatively analyzing the loss degree;
5) And (4) overall evaluation of filling strength and dissipation degree of the gas reservoir.
In the step 1), the sample is selected to meet the following conditions:
(1) The sample permeability must cover 0.01X 10 -3 μm 2 ～1.0×10 -3 μm 2 ；
(2) Permeability of 0.01X 10 -3 μm 2 ～0.1×10 -3 μm 2 Samples of (4), permeability interval less than 0.03X 10 -3 μm 2 Permeability of 0.1X 10 -3 μm 2 ～1.0×10 -3 μm 2 Samples of (4) with a permeability interval of less than 0.2X 10 -3 μm 2 。
Establishing a relation curve of permeability and irreducible water saturation by adopting a natural gas filling method in the step 1), and establishing a relation formula of the permeability and the irreducible water saturation, wherein Swi (k) = a i *ln(K)+b i (ii) a Wherein k is permeability, a i And b i Is a constant.
In the step 2), collecting an electrical logging curve and an interpretation result of the gas well in the research range, extracting the physical property of the target gas reservoir and the corresponding water saturation, and fitting a relation curve, wherein the concrete steps are as follows:
(1) And on the basis of the existing logging interpretation data, selecting and recording the water saturation corresponding to the sandstone section by combining the logging physical property interpretation result.
(2) The requirement must include a non-reservoir section sandstone interpretation permeability and water saturation less than or below the permeability lower limit; i.e. permeability of 0.01X 10 -3 μm 2 ～0.1×10 -3 μm 2 The water saturation corresponding to the sandstone;
(3) Establishing a relation curve of the well permeability and the water saturation; the relationship between the well permeability and the water saturation, sw o (k)=a o *ln(k)+b o (ii) a Wherein k is permeability, a o And b o Is a constant;
(4) And (4) repeating the steps (1) to (3) to establish the relation curves and the relation formulas of the permeability and the water saturation of all the drilled wells.
The filling degree qualitative and quantitative analysis in the step 3) comprises the following specific steps:
(1) Placing the well completion permeability-water saturation scattering point in a qualitative judgment plate of the filling strength and scattering degree of the compact gas reservoir, if the permeability is 0.01 multiplied by 10 -3 μm 2 ～0.1×10 -3 μm 2 In the interval range, if the dispersion point is positioned below the saturation curve of the bound water, the filling strength of the well is high, and if the dispersion point is positioned above the saturation curve of the bound water, the filling strength is insufficient;
(2) Filling intensity index k =0.01 × 10 -3 μm 2 Time Sw i (k)-Sw o (k) Is greater than 0, indicating a high degree of filling, and is less than 0, indicating a low degree of filling. The larger the filling intensity index is, the higher the degree of filling of the depot;
(3) And calculating the filling intensity index well by well, completing the drawing of a filling intensity index plane equivalent graph, and enabling the filling degree of the high-value area to be high, thereby being a favorable accumulation area.
In the step 4), the loss degree is qualitatively and quantitatively analyzed, and the method specifically comprises the following steps:
(1) If the well permeability-water saturation relation curve is nearly parallel or the slope is smaller than the permeability-irreducible water saturation curve, the gas reservoir or the area where the well is located can be judged to be not lost; if the slope of the relation curve of permeability-water saturation is larger than the permeability-irreducible water saturation curve, the loss of the gas reservoir or the area where the well is located can be judged;
(2) Defining a difference a between the slope of a permeability-water saturation relationship curve and the slope of a permeability-irreducible water saturation relationship curve i -a o Is a loss index; if the scattering index is negative, scattering does not occur, if the scattering index is normal, scattering exists, and the scattering is more serious if the scattering index value is larger;
(3) Calculating the loss index well by well, completing the planar equivalent graph drawing of the loss index, wherein the negative value area has good storage condition, the positive value area has loss of natural gas, and the negative value area is a favorable accumulation area.
And 5) integrally evaluating the filling strength and the dissipation degree of the gas reservoir, wherein the specific steps are as follows:
(1) Putting the quantitative evaluation result data of the gas reservoir filling strength and the scattering index into an integral evaluation chart of the gas reservoir filling strength and the scattering degree, and then carrying out integral evaluation on the gas reservoir filling strength and the scattering degree; the area A shows that the gas reservoir filling intensity is high, and the storage condition is good; the area B shows that the gas reservoir filling intensity is high, and the storage condition is poor; the area C shows that the gas reservoir filling intensity is insufficient, and the storage condition is poor; the area D shows that the gas reservoir filling intensity is insufficient, and the storage condition is met;
(2) And overlapping the region with positive filling intensity index plane equivalence map and the region with negative dissipation index plane equivalence map curve, wherein the overlapping region of the two regions is a favorable natural gas accumulation region.
The invention has the beneficial effects that:
the invention provides an economic, effective, simple and quick evaluation method aiming at the analysis of the compact gas reservoir formation condition. The defects of large workload, long period, high cost and the like of a large amount of experiments and mathematical calculations such as analysis of a large amount of hydrocarbon source rocks, evaluation of reservoir storage conditions, basin simulation and the like in the original gas reservoir evaluation process are overcome. The method is applied to the evaluation project of the gas reservoir of the Surieger tight sandstone in the Ordos basin, so that the analysis and test costs are saved by 551.3 ten thousand yuan, the project research period is shortened by 150 days, and the gas reservoir research efficiency and reliability are improved.
The following will be further described with reference to the accompanying drawings.
Drawings
FIG. 1 is a diagram of qualitative judgment of filling strength and dissipation degree of tight gas reservoir.
FIG. 2 is a chart of the overall evaluation of occlusion filling strength and extent of effusivity.
Detailed Description
Example 1:
the invention provides a quantitative evaluation method for filling strength and dissipation degree of a compact gas reservoir, aiming at solving the problems of large workload, long period and high cost of a large number of experiments and mathematical calculations such as a large number of hydrocarbon source rock analyses, reservoir storage condition evaluation, basin simulation and the like in the original gas reservoir evaluation process. Based on the rule, the filling intensity and the storage condition of the compact gas reservoir can be judged through analyzing the relation between the existing physical property and the gas content of the gas reservoir. The invention does not need to collect a large amount of rock samples and perform experimental analysis, and only needs to analyze the well logging explanation of the existing well. The method has universality for the dense gas reservoir, can give quantitative evaluation results, and is beneficial to the comparative analysis among the gas reservoirs of the same type. A quantitative evaluation method for filling strength and dissipation degree of a tight gas reservoir comprises the following specific steps:
1) Establishing a relation curve of reservoir permeability and irreducible water saturation, and selecting a core sample within a permeability range according to a tight gas reservoir permeability distribution range;
2) Collecting an electrical logging curve and an explanation result of the gas well in the research range, extracting the physical property of the target gas reservoir and the corresponding water saturation, and fitting a relation curve;
3) Qualitatively and quantitatively analyzing the filling degree;
4) Qualitatively and quantitatively analyzing the loss degree;
5) And (4) overall evaluation of filling strength and dissipation degree of the gas reservoir formation.
The process shows that the method mainly comprises three steps of firstly establishing a permeability-irreducible water saturation chart, mainly selecting different reservoir characteristic rock cores to perform physical analysis, preferably selecting different permeability rock cores, establishing irreducible water saturation in a gas water-driving mode, and establishing the permeability-irreducible water saturation chart according to an experimental result. And secondly, collecting a logging data band and explaining, extracting data according to the change characteristics of the permeability of the reservoir, and establishing a relation curve between the permeability and the water saturation. On the basis of the two steps, the filling degree and the dissipation degree are qualitatively evaluated through a permeability and water saturation chart, and can also be quantitatively evaluated through a related mathematical formula. And finally, according to the quantitative evaluation result, the overall evaluation of the gas reservoir filling degree and the scattering degree can be completed through an overall evaluation chart of the filling strength and the scattering degree.
Example 2:
based on embodiment 1, in this embodiment, preferably, in step 1), the sample is selected to satisfy the following condition:
(1) The sample permeability must cover 0.01X 10 -3 μm 2 ～1.0×10 -3 μm 2 ；
(2) Permeability of 0.01X 10 -3 μm 2 ～0.1×10 -3 μm 2 Samples of (4), permeability interval less than 0.03X 10 -3 μm 2 Permeability of 0.1X 10 -3 μm 2 ～1.0×10 -3 μm 2 Samples of (4), permeability interval less than 0.2X 10 -3 μm 2 。
Preferably, in the step 1), a natural gas filling method is adopted to establish a permeability-irreducible water saturation relation curve, and the permeability-irreducible water saturation relation is Swi (k) = a i *ln(K)+b i (ii) a Wherein k is permeability, a i And b i Is a constant. In a certain area, a o 、b o Is constant during the application processExperiments were performed for each field, constants were different, a i And b i The value of (c) depends on the different gas fields.
Preferably, in the step 2), an electrical logging curve and an interpretation result of the gas well in the research range are collected, the physical property of the target gas reservoir and the corresponding water saturation are extracted, and a relation curve is fitted, wherein the specific steps are as follows:
(1) And on the basis of the existing logging interpretation data, selecting and recording the water saturation corresponding to the sandstone section by combining the logging physical property interpretation result.
(2) The requirement must include a non-reservoir section sandstone interpretation permeability and water saturation less than or below the permeability lower limit; i.e. permeability of 0.01X 10 -3 μm 2 ～0.1×10 -3 μm 2 The water saturation corresponding to the sandstone;
(3) Establishing a relation curve of the well permeability and the water saturation; the relationship between the well permeability and the water saturation, sw o (k)=a o *ln(k)+b o (ii) a Wherein k is permeability, a o And b o Is a constant; in the application process, each gas field is tested, the constants are different, a o And b o The value of (c) depends on the different gas fields.
(4) And (4) repeating the steps (1) to (3) to establish the relation curves and the relation formulas of the permeability and the water saturation of all the drilled wells.
Preferably, the filling degree qualitative and quantitative analysis in the step 3) comprises the following specific steps:
(1) Placing the well completion permeability-water saturation scattering point in a qualitative judgment plate of the filling strength and scattering degree of the compact gas reservoir, if the permeability is 0.01 multiplied by 10 -3 μm 2 ～0.1×10 -3 μm 2 In the interval range, if the dispersion point is positioned below the saturation curve of the bound water, the filling strength of the well is high, and if the dispersion point is positioned above the saturation curve of the bound water, the filling strength is insufficient;
(2) Filling intensity index k =0.01 × 10 -3 μm 2 Time Sw i (k)-Sw o (k) Is measured in%, filledA strength index greater than 0 indicates a high degree of filling and a filling strength index less than 0 indicates a low degree of filling. The larger the filling intensity index is, the higher the degree of filling of the depot;
(3) And calculating the filling intensity index from well to well, completing the drawing of a filling intensity index plane equivalent graph, wherein the filling degree of the high-value area is high, and the high-value area is a favorable accumulation area.
Preferably, in the step 4), the loss degree is qualitatively and quantitatively analyzed, and the method specifically comprises the following steps:
(1) If the well permeability-water saturation relation curve is nearly parallel or the slope is smaller than the permeability-irreducible water saturation curve, the gas reservoir or the area where the well is located can be judged to be not lost; if the slope of the relation curve of permeability-water saturation is larger than the permeability-irreducible water saturation curve, the loss of the gas reservoir or the area where the well is located can be judged;
(2) Defining a difference a between the slope of a permeability-water saturation relationship curve and the slope of a permeability-irreducible water saturation relationship curve i -a o Is a loss index; if the loss index is negative, the loss is not lost, if the loss index is regular, the loss exists, and if the loss index value is larger, the loss is more serious;
(3) And calculating the loss index well by well, completing the drawing of a loss index plane equivalent diagram, wherein the negative value area has good storage condition, the positive value area has loss of natural gas, and the negative value area is a favorable accumulation area.
Preferably, in the step 5), the overall evaluation of the filling strength and the dissipation degree of the gas reservoir formation is carried out by the following specific steps:
(1) Putting the quantitative evaluation result data of the gas reservoir filling strength and the scattering index into an integral evaluation chart of the gas reservoir filling strength and the scattering degree, and then carrying out integral evaluation on the gas reservoir filling strength and the scattering degree; the area A shows that the gas reservoir filling intensity is high, and the storage condition is good; the area B shows that the gas reservoir filling intensity is high, and the storage condition is poor; the area C indicates that the gas reservoir filling intensity is insufficient and the storage condition is poor; the area D shows that the gas reservoir filling intensity is insufficient, and the storage conditions are met;
(2) And overlapping a region with a positive filling intensity index plane equivalent graph and a region with a negative dispersion index plane equivalent graph curve, wherein an overlapping region of the two regions is a favorable natural gas accumulation region.
As shown in FIG. 1, FIG. 1 is a qualitative determination chart of filling intensity and dissipation degree of dense gas reservoir, which is a qualitative determination chart of filling intensity and dissipation degree of dense gas reservoir, 0.01 × 10 -3 μm 2 ～0.1×10 -3 μm 2 And the permeability interval is a filling strength rapid identification area, if the water saturation of the storage layer in the permeability section is below the irreducible water gas saturation line, the filling degree is high, and if the water saturation is above the irreducible water saturation line, the gas reservoir filling strength is insufficient. If the fitted permeability saturation curve is substantially parallel to the irreducible water saturation curve, it is indicated that the storage condition is good, and if the slope of the fitted permeability saturation curve is greater than the irreducible water saturation curve, it is indicated that scattering exists, and the scattering is more serious if the slope is greater.
As shown in fig. 2, fig. 2 is an overall evaluation chart of the reservoir filling strength and the depletion degree, which is an overall evaluation chart of the reservoir filling strength and the depletion degree of the dense gas reservoir, and if the calculated gas reservoir filling index and the depletion index are located in a region a, it indicates that the gas reservoir filling strength is high and the storage condition is good; if the gas reservoir data point falls in the area B, the gas reservoir filling intensity is high, and the storage condition is poor; if the gas reservoir data point falls in the area C, the gas reservoir filling strength is insufficient, and the storage condition is poor; if the gas reservoir data point falls in the D area, the gas reservoir filling strength is insufficient, and the storage condition is good.
The invention provides an economic, effective, simple and quick evaluation method aiming at the analysis of the compact gas reservoir formation condition. The defects of large workload, long period, high cost and the like of a large amount of experiments and mathematical calculations such as analysis of a large number of hydrocarbon source rocks, evaluation of storage conditions of a reservoir, basin simulation and the like in the original gas reservoir evaluation process are overcome. The method is applied to the evaluation project of the gas reservoir of the Surieger tight sandstone in the Ordos basin, so that the analysis and test costs are saved by 551.3 ten thousand yuan, the project research period is shortened by 150 days, and the gas reservoir research efficiency and reliability are improved.
Example 3:
based on embodiments 1 and 2, the present embodiment provides a method for quantitatively evaluating filling strength and dissipation degree of a dense gas reservoir, which includes the following specific steps:
1) And establishing a relation curve of the reservoir permeability and the irreducible water saturation.
Selecting a core sample within the permeability range according to the permeability distribution range of the compact gas reservoir, wherein the sample selection meets the following conditions:
(1) The sample permeability must cover 0.01X 10 -3 μm 2 ～1.0×10 -3 μm 2 。
(2) Permeability of 0.01X 10 -3 μm 2 ～0.1×10 -3 μm 2 Samples of (4) with a permeability interval of less than 0.03X 10 -3 μm 2 Permeability of 0.1X 10 -3 μm 2 ～1.0×10 -3 μm 2 Samples of (4) with a permeability interval of less than 0.2X 10 -3 μm 2 。
(3) And establishing a relation curve of permeability and irreducible water saturation by adopting a natural gas filling method. The natural gas filling method is prior art, and will not be further described in the present invention.
(4) Establishing a relation between permeability and irreducible water saturation, swi (k) = a i *ln(K)+b i 。
2) Collecting an electrical logging curve and an explanation result of a gas well in a research range, extracting the physical property of a target gas reservoir and the corresponding water saturation, and fitting a relation curve, wherein the concrete steps are as follows:
(1) On the basis of the existing well logging interpretation data, the corresponding water saturation of the sandstone section is selected and recorded in combination with the well logging physical interpretation result.
(2) The requirement must include a non-reservoir segment sandstone interpretation permeability and water saturation less than or below the lower permeability limit. I.e. permeability of 0.01X 10 -3 μm 2 ～0.1×10 -3 μm 2 The sandstone rock of (a).
(3) And establishing a relation curve of the well permeability and the water saturation.
(4) Establishing a relationship, sw, between the well permeability and the water saturation o (k)=a o *ln(k)+b o 。
(5) And (5) repeating the steps (1) to (4) to establish the relation curves and the relation formulas of the permeability and the water saturation of all the completed wells.
3) Qualitative and quantitative analysis of filling level
(1) The permeability-water saturation scatter of the well completion is placed in the plate shown in figure 1 if the permeability is 0.01 x 10 -3 μm 2 ～0.1×10 -3 μm 2 In the interval range, if the dispersion point is positioned below the saturation curve of the bound water, the filling strength of the well is high, and if the dispersion point is positioned above the saturation curve of the bound water, the filling strength is insufficient.
(2) Filling intensity index k =0.01 × 10 -3 μm 2 Time Sw i (k)-Sw o (k) Is greater than 0, indicating a high degree of filling, and is less than 0, indicating a low degree of filling. The greater the filling intensity index, the greater the degree of reservoir filling.
(3) And calculating the filling intensity index from well to well, completing the drawing of a filling intensity index plane equivalent graph, wherein the filling degree of the high-value area is high, and the high-value area is a favorable accumulation area.
4) Qualitative and quantitative analysis of loss degree
(1) If the permeability-water saturation relation curve is nearly parallel or the slope is smaller than the permeability-irreducible water saturation curve, the gas reservoir or the area where the well is located can be judged to be free of loss; if the slope of the permeability-water saturation relationship curve is greater than the permeability-irreducible water saturation curve, then the loss of the gas reservoir or the area where the well is located can be determined.
(2) Defining a difference a between the slope of a permeability-water saturation relationship curve and the slope of a permeability-irreducible water saturation relationship curve i -a o Is an index of loss. If the scattering index is negative, scattering does not occur, if the scattering index is normal, scattering exists, and the scattering is more serious if the scattering index value is larger.
(3) Calculating the loss index well by well, completing the planar equivalent graph drawing of the loss index, wherein the negative value area has good storage condition, the positive value area has loss of natural gas, and the negative value area is a favorable accumulation area.
5) Overall evaluation of filling strength and dissipation degree of gas reservoir formation
(1) And putting the result data of quantitative evaluation of the gas reservoir filling strength and the gas reservoir scattering index into a chart as shown in figure 2, and then carrying out overall evaluation on the gas reservoir filling strength and scattering degree. The area A shows that the gas reservoir filling intensity is high, and the storage condition is good; the area B shows that the gas reservoir filling intensity is high, and the storage condition is poor; the area C shows that the gas reservoir filling intensity is insufficient, and the storage condition is poor; the area D shows that the gas reservoir filling intensity is insufficient and the storage condition is good.
(2) And overlapping a region with a positive filling intensity index plane equivalent graph and a region with a negative dispersion index plane equivalent graph curve, wherein an overlapping region of the two regions is a favorable natural gas accumulation region.
For example, the sux block box 8 tight sandstone gas reservoir:
1. and (4) finishing physical property analysis by selecting a typical rock sample.
2. According to the physical property test results, respectively selecting.01X 10 -3 μm 2 -0.1×10 -3 μm 2 Sample 5, 0.1X 10 -3 μm 2 -1.0×10 -3 μm 2 Sample 5, 1.0X 10 -3 μm 2 -10.0×10 -3 μm 2 And 2 samples are subjected to a gas drive water bound water saturation experiment, and a relation curve of permeability and bound water saturation is established.
3. Collecting 25 well logging interpretation data uniformly distributed in the research area, and extracting permeability of 0.01 × 10 from the well logging interpretation data -3 μm 2 -0.1×10 -3 μm 2 And 0.1X 10 -3 μm 2 -1.0×10 -3 μm 2 And (4) the water saturation corresponding to the data points and a fitting formula.
4. The extracted data were placed in the plate shown in FIG. 1 with a well permeability of 0.01X 10 -3 μm 2 -0.1×10 -3 μm 2 The data points within the range are all below the irreducible water saturation line, indicating that the area is highly filled.
5. The slope of the curve fitted to the data points is greater than the slope of the irreducible water saturation line, indicating the presence of depletion in the area.
6. The filling intensity index and the loss index of the selected 25 wells are calculated one by one and are placed in the chart shown in the attached figure 2, and the filling intensity index and the loss index are all positioned in a zone B, so that the block box 8 is high in gas reservoir forming filling intensity, but poor in storage condition and obvious in natural gas leakage.
The above examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention, which is intended to be covered by the claims. The process steps described in detail in the present invention are prior art and will not be further described in the present invention.
Claims (6)
1. A quantitative evaluation method for filling strength and dissipation degree of a dense gas reservoir is characterized by comprising the following steps: the method comprises the following specific steps:
1) Establishing a relation curve of reservoir permeability and irreducible water saturation, and selecting a core sample within a permeability range according to a tight gas reservoir permeability distribution range;
2) Collecting an electrical logging curve and an explanation result of the gas well in the research range, extracting the physical property of the target gas reservoir and the corresponding water saturation, and fitting a relation curve;
3) Performing qualitative and quantitative analysis on filling degree;
4) Analyzing the loss degree qualitatively and quantitatively;
5) Integrally evaluating filling strength and dissipation degree of the gas reservoir formation;
the quantitative evaluation method for the filling strength and the dissipation degree of the dense gas reservoir is characterized by comprising the following steps of: in the step 2), collecting an electrical logging curve and an interpretation result of the gas well in the research range, extracting the physical property of the target gas reservoir and the corresponding water saturation, and fitting a relation curve, wherein the concrete steps are as follows:
(1) On the basis of the existing well logging interpretation data, the corresponding water saturation of the sandstone section is selected and recorded in combination with the well logging physical interpretation result;
(2) The requirement must include less than the non-reservoir zone below the lower permeability limitInterpreting permeability and water saturation by the sandstone; i.e. permeability of 0.01X 10 -3 μm 2 ～0.1×10 -3 μm 2 The water saturation corresponding to the sandstone;
(3) Establishing a relation curve of the well permeability and the water saturation; the relationship between the well permeability and the water saturation, sw o (k)=a o *ln(k)+b o (ii) a Wherein k is permeability, a o And b o Is a constant;
(4) And (4) repeating the steps (1) to (3) to establish the relation curves and the relation formulas of the permeability and the water saturation of all the drilled wells.
2. The method for quantitatively evaluating the filling strength and the dissipation degree of the dense gas reservoir as claimed in claim 1, wherein: in the step 1), the sample selection meets the following conditions:
(1) The sample permeability must cover 0.01X 10 -3 μm 2 ～1.0×10 -3 μm 2 ；
(2) Permeability of 0.01X 10 -3 μm 2 ～0.1×10 -3 μm 2 Samples of (4) with a permeability interval of less than 0.03X 10 -3 μm 2 Permeability of 0.1X 10 -3 μm 2 ～1.0×10 -3 μm 2 Samples of (4), permeability interval less than 0.2X 10 -3 μm 2 。
3. The method for quantitatively evaluating the filling strength and the dissipation degree of the dense gas reservoir as claimed in claim 1, wherein: establishing a relation curve of permeability and irreducible water saturation by adopting a natural gas filling method in the step 1), and establishing a relation formula of the permeability and the irreducible water saturation, wherein Swi (k) = a i *ln(K)+b i (ii) a Wherein k is permeability, a i And b i Is a constant.
4. The method for quantitatively evaluating the filling strength and the dissipation degree of the dense gas reservoir as claimed in claim 1, wherein: the qualitative and quantitative analysis of the filling degree in the step 3) comprises the following specific steps:
(1) Placing the well permeability-water saturation scattering point in qualitative identification chart of filling strength and scattering degree of tight gas reservoir, if the permeability is 0.01X 10 -3 μm 2 ～0.1×10 -3 μm 2 In the interval range, if the dispersion point is positioned below the saturation curve of the bound water, the filling strength of the well is high, and if the dispersion point is positioned above the saturation curve of the bound water, the filling strength is insufficient;
(2) Filling intensity index k =0.01 × 10 -3 μm 2 Time Sw i (k)-Sw o (k) The filling strength index is larger than 0 in unit percent, which indicates that the filling degree is high, and the filling strength index is smaller than 0, which indicates that the filling degree is low; the larger the filling intensity index is, the higher the stocking filling degree is;
(3) And calculating the filling intensity index from well to well, completing the drawing of a filling intensity index plane equivalent graph, wherein the filling degree of the high-value area is high, and the high-value area is a favorable accumulation area.
5. The method for quantitatively evaluating the filling strength and the dissipation degree of the dense gas reservoir as claimed in claim 1, wherein: in the step 4), the loss degree is qualitatively and quantitatively analyzed, and the method specifically comprises the following steps:
(1) If the permeability-water saturation relation curve is nearly parallel or the slope is smaller than the permeability-irreducible water saturation curve, the gas reservoir or the area where the well is located can be judged to be free of loss; if the slope of the relation curve of permeability-water saturation is larger than the permeability-irreducible water saturation curve, the loss of the gas reservoir or the area where the well is located can be judged;
(2) Defining a difference a between the slope of a permeability-water saturation relationship curve and the slope of a permeability-irreducible water saturation relationship curve i -a o Is a loss index; if the loss index is negative, the loss is not lost, if the loss index is regular, the loss exists, and if the loss index value is larger, the loss is more serious;
(3) Calculating the loss index well by well, completing the planar equivalent graph drawing of the loss index, wherein the negative value area has good storage condition, the positive value area has loss of natural gas, and the negative value area is a favorable accumulation area.
6. The method for quantitatively evaluating the filling strength and the dissipation degree of the dense gas reservoir as claimed in claim 1, wherein: and 5) integrally evaluating the filling strength and the dissipation degree of the gas reservoir, wherein the specific steps are as follows:
(1) Putting the quantitative evaluation result data of the gas reservoir filling strength and the scattering index into an integral evaluation chart of the gas reservoir filling strength and the scattering degree, and then carrying out integral evaluation on the gas reservoir filling strength and the scattering degree; the area A shows that the gas reservoir filling intensity is high, and the storage condition is good; the area B shows that the gas reservoir filling intensity is high, and the storage condition is poor; the area C shows that the gas reservoir filling intensity is insufficient, and the storage condition is poor; the area D shows that the gas reservoir filling intensity is insufficient, and the storage conditions are met;
(2) And overlapping the region with positive filling intensity index plane equivalence map and the region with negative dissipation index plane equivalence map curve, wherein the overlapping region of the two regions is a favorable natural gas accumulation region.
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