Oil saturation is a critical parameter when designing oil field development plans.This study focuses on the change of oil saturation during water flooding.Particularly,a meter-level artificial model is used to conduct...Oil saturation is a critical parameter when designing oil field development plans.This study focuses on the change of oil saturation during water flooding.Particularly,a meter-level artificial model is used to conduct relevant experiments on the basis of similarity principles and taking into account the layer geological characteristics of the reservoir.The displacement experiment’s total recovery rate is 41.35%.The changes in the remaining oil saturation at a millimeter-scale are examined using medical spiral computer tomography principles.In all experimental stages,regions exists where the oil saturation decline is more than 10.0%.The shrinkage percentage is 20.70%in the horizontal well production stage.The oil saturation reduction in other parts is less than 10.0%,and there are regions where the oil saturation increases in the conventional water flooding stage.展开更多
Heterogeneous reservoir characteristics for oilfield, choose HS-1 non-ionic surfactant and polymer formation in binary combination flooding system can significantly improve the rate of production of low permeability r...Heterogeneous reservoir characteristics for oilfield, choose HS-1 non-ionic surfactant and polymer formation in binary combination flooding system can significantly improve the rate of production of low permeability reservoir in heterogeneous reservoir. According to the core flooding experiment analyzed longitudinal heterogeneous models, single surfactant and a single polymer and polymer flooding of table binary complex drive effect. Studies show that binary combination flooding recovery effect is best, followed by polymer flooding, minimum of surfactant flooding, in heterogeneous reservoir.展开更多
Taking reservoir rocks and fluids of the Daqing,Dagang and Changqing oilfields as research objects,the EOR mechanisms and technical approach of polymer flooding were discussed.By comparing the displacement performance...Taking reservoir rocks and fluids of the Daqing,Dagang and Changqing oilfields as research objects,the EOR mechanisms and technical approach of polymer flooding were discussed.By comparing the displacement performances of ordinary polymer,glycerol,polymer in"sheet-net"structure and heterogeneous weak gel at the same viscosity and concentration,the relationship between the viscosity of polymer displacement agents and displacement performance was demonstrated,and the method of improving polymer flooding effect was worked out.The main mechanism of polymer flooding to increase oil recovery is the swept volume expansion of water injection due to polymer retention in porous media.The viscosity of polymer agents has no positive correlation with polymer flooding effect.Although polymer of"sheet-net"structure has strong capacity in increasing viscosity,it has poor compatibility with pore throat structure of reservoir rock,low injectivity and low shear resistance.Heterogeneous weak gel system has higher adsorption and capture capacity in porous media,which is easy to retain in porous media,and can effectively establish seepage resistance in high permeability layers(zones).Compared with polymer solutions with the same viscosity or concentration,it has stronger ability to expand swept volume.Long term injection of polymer flooding agents will inevitably lead to fluid entry profile reversal,and thus worsening of polymer flooding effect.Alternate injection of high retention and low or non-retention displacement agents can further improve the displacement effect of polymer flooding agents.展开更多
An environmentally benign process was devel-oped for the transesterification of Jatropha curcas L. seed oil with methanol using artificial zeolites loaded with potassium acetate as a heterogeneous catalyst. After calc...An environmentally benign process was devel-oped for the transesterification of Jatropha curcas L. seed oil with methanol using artificial zeolites loaded with potassium acetate as a heterogeneous catalyst. After calcination for 5 h at 823 K, the catalyst loaded with 47 wt.% CH3COOK exhibited the highest efficiency and best catalytic activity. The easily prepared cata-lysts were characterized by means of X-ray dif-fraction and IR spectroscopy, as well as Hammett indicator titration. The results revealed a strong dependence of catalytic activity on ba-sicity. The optimum reaction conditions for transesterification of J. curcas oil were also in-vestigated. The methyl ester content in the bio-diesel product exceeded 91% after 4h reaction at reflux temperature in the presence of 2% solid catalyst and no water washing process is needed during workup.展开更多
Energy obtained from a variety of non-renewable sources is considered unsustainable. Various fossil fuels, such as petroleum, coal, and natural gas, are among these sources. The combustion of fossil fuels resulted in ...Energy obtained from a variety of non-renewable sources is considered unsustainable. Various fossil fuels, such as petroleum, coal, and natural gas, are among these sources. The combustion of fossil fuels resulted in the generation of greenhouse gases, which increased the amount of carbon dioxide in the atmosphere. Global warming and ozone layer degradation are the negative consequences. In a country like India, where consumable oils are still imported, it is sense to look at the possibility of using such unpalatable oils in CI engines that aren’t often utilized as cooking oil. Palm oil is a vegetable oil obtained from the monocarp of the oil palm’s crop. The main goal is to provide a low-cost, high-performance alternative to diesel. The possibility of palm oil as a realistic, modest, and effective hotspot for the generation of biodiesel is investigated in this research. The article is focused on the comparison of palm oil and diesel in terms of characteristics.展开更多
Based on the comparison of basic geological conditions and enrichment characteristics of shale oil plays, the heterogeneity of source and reservoir conditions and differential enrichment of medium-high maturity contin...Based on the comparison of basic geological conditions and enrichment characteristics of shale oil plays, the heterogeneity of source and reservoir conditions and differential enrichment of medium-high maturity continental shale oil plays in China have been confirmed.(1) Compared with the homogeneous geological settings and wide distribution of marine shale oil strata in North America, the continental medium and high maturity shale oil plays in China are significantly different in geological conditions generally;continental multi-cyclic tectonic evolution forms multiple types of lake basins in multi-stages, providing sites for large-scale development of continental shale oil, and giving rise to large scale high-quality source rocks, multiple types of reservoirs, and diverse source-reservoir combinations with significant heterogeneity.(2) The differences in sedimentary water environments lead to the heterogeneity in lithology, lithofacies, and organic material types of source rocks;the differences in material source supply and sedimentary facies belt result in reservoirs of different lithologies, including argillaceous and transition rocks, and tight siltstone, and complex source-reservoir combination types.(3) The heterogeneity of the source rock controls the differentiation of hydrocarbon generation and expulsion, the diverse reservoir types make reservoir performance different and the source-reservoir configurations complex, and these two factors ultimately make the shale oil enrichment patterns different. Among them, the hydrocarbon generation and expulsion capacity of high-quality source rocks affect the degree of shale oil enrichment. Freshwater hydrocarbon source rocks with TOC larger than 2.5% and saline hydrocarbon source rocks with TOC of 2% to 10% have a high content of retained hydrocarbons and are favorable.(4) High-abundance organic shale is the basis for the enrichment of shale oil inside the source. In addition to being retained in shale, liquid hydrocarbons migrate along laminae, diagenetic fractures, and thin sandy layers, and then accumulate in laminae of argillaceous siltstone, siltstone, and argillaceous dolomite, and dolomitic siltstone suites, etc. with low organic matter abundance in the shale strata, resulting in differences in enrichment pattern.展开更多
Waste cooking oil(WCO) is becoming the most promising alternative feedstock to produce biodiesel due to its low cost in China. In this study, NKC-9 ion-exchange resin and H-beta zeolite were selected as heterogeneous ...Waste cooking oil(WCO) is becoming the most promising alternative feedstock to produce biodiesel due to its low cost in China. In this study, NKC-9 ion-exchange resin and H-beta zeolite were selected as heterogeneous catalysts in the WCO esterification process and their esterification characteristics were compared by orthogonal experiments. NKC-9 resin showed higher activity and achieved a higher final conversion compared with H-beta zeolite under the same reaction conditions. Reusability experiments showed that NKC-9 resin still exhibited high activity after 5 runs. The effects of the mole ratio of alcohol to oil, reaction time, reaction temperature and the catalyst dose were investigated by multifactor orthogonal analysis. The influence of the free fatty acid(FFA) content was also investigated, and the result showed that the esterification rate could be as high as 98.4% when the FFA content was 6.3wt%.展开更多
During the displacement of water plugging with binary flooding in internally heterogeneous reservoirs,it is essential to understand the distributions of remaining oil as well as the oil displacement mechanisms at diff...During the displacement of water plugging with binary flooding in internally heterogeneous reservoirs,it is essential to understand the distributions of remaining oil as well as the oil displacement mechanisms at different stages.In this study,two types of internally heterogeneous systems,i.e.,vertical and horizontal wells are investigated experimentally through a microscopic approach.The results show that plugging agent types have a greater impact on oil recovery than well types,and foam injection can enhance oil recovery more effectively than gel injection.Additionally,the injection sequence of plugging agents significantly affects oil displacement efficiency.Injecting gel after foam is more beneficial.According to the present results,the main formation mechanisms of remaining oil in each displacement stage are influenced by:capillary force,viscous force,inertial force,shear force,microscopic fingering&channeling.展开更多
Waterflooding experiments were performed using Micro-CT on four cores of different pore structures from Donghe sandstone reservoirs in the Tarim Basin. The water, oil and grains were accurately separated by the advanc...Waterflooding experiments were performed using Micro-CT on four cores of different pore structures from Donghe sandstone reservoirs in the Tarim Basin. The water, oil and grains were accurately separated by the advanced image processing technology, the pore network model was established, and parameters such as the number of throats and the throat size distribution were calculated to characterize the microscopic heterogeneity of pore structure, the flow of oil phase during displacement, and the morphology and distribution of remaining oil after displacement. The cores with the same macroscopic porosity-permeability have great differences in microscopic heterogeneity of pore structure. Both macro porosity-permeability and micro heterogeneity of pore structure have an influence on the migration of oil phase and the morphology and distribution of remaining oil. When the heterogeneity is strong, the water phase will preferentially flow through the dominant paths and the remaining oil clusters will be formed in the small pores. The more the number of oil clusters(droplets) formed during displacement process, the smaller the average volume of cluster is, and the remaining oil is dominated by the cluster continuous phase with high saturation. The weaker the heterogeneity, the higher the pore sweep efficiency is, and the remaining oil clusters are mainly trapped in the form of non-continuous phase. The distribution and morphology of micro remaining oil are related to the absolute permeability, capillary number and micro-heterogeneity. So, the identification plate of microscopic residual oil continuity distribution established on this basis can describe the relationship between these three factors and distribution of remaining oil and identify the continuity of the remaining oil distribution accurately.展开更多
The Linnan subsag is the main oil producer of the Linpan oil zone. Based on the oil group composition,gas chromatography data and biomarker analysis,it was indicated that crude oils from different oilfields varied gre...The Linnan subsag is the main oil producer of the Linpan oil zone. Based on the oil group composition,gas chromatography data and biomarker analysis,it was indicated that crude oils from different oilfields varied greatly in group composition and showed obvious heterogeneities in the aspects of precursor type,crude oil maturity and hydrocarbon depositional environment. According to the characteristics of source rocks,three oil populations can be distinguished,i.e.,the southern,northern and transitional oil populations. Furthermore,on the basis of post-reservoir reworking processes,the medium conditions of hydrocarbon-generating environment and differences in maturity,six oil families and twelve sub-families were distinquished. An integrated study suggested that the fac-tors leading to such heterogeneities in crude oil composition mainly include different source rocks,multi-stage oil/gas charging,geo-chromatographic effects during oil/gas migration,reservoir heterogeneities and various post-reservoir secondary alterations.展开更多
Drilling results suggest that the thickness of natural gas hydrates(NGHs)in the Shenhu Area,South China Sea(SCS)are spatially heterogenous,making it difficult to accurately assess the NGHs resources in this area.In th...Drilling results suggest that the thickness of natural gas hydrates(NGHs)in the Shenhu Area,South China Sea(SCS)are spatially heterogenous,making it difficult to accurately assess the NGHs resources in this area.In the case that free gas exists beneath hydrate deposits,the frequency of the hydrate deposits will be noticeably attenuated,with the attenuation degree mainly affected by pore development and free gas content.Therefore,the frequency can be used as an important attribute to identify hydrate reservoirs.Based on the time-frequency characteristics of deposits,this study predicted the spatial distribution of hydrates in this area using the frequency division inversion method as follows.Firstly,the support vector machine(SVM)method was employed to study the amplitude versus frequency(AVF)response based on seismic and well logging data.Afterward,the AVF response was introduced as independent information to establish the nonlinear relationship between logging data and seismic waveform.Then,the full frequency band information of the seismic data was fully utilized to obtain the results of frequency division inversion.The inversion results can effectively broaden the frequency band,reflect the NGHs distribution,and reveal the NGHs reservoirs of two types,namely the fluid migration pathway type and the in situ self-generation self-storage diffusion type.Moreover,the inversion results well coincide with the drilling results.Therefore,it is feasible to use the frequency division inversion to predict the spatial distribution of heterogeneous NGHs reservoirs,which facilitates the optimization of favorable drilling targets and is crucial to the resource potential assessment of NGHs.展开更多
基金supported by the National Science and Technology Major Projects of China for Oil and Gas(Projects Nos.2016ZX05010 and 2016ZX05058).
文摘Oil saturation is a critical parameter when designing oil field development plans.This study focuses on the change of oil saturation during water flooding.Particularly,a meter-level artificial model is used to conduct relevant experiments on the basis of similarity principles and taking into account the layer geological characteristics of the reservoir.The displacement experiment’s total recovery rate is 41.35%.The changes in the remaining oil saturation at a millimeter-scale are examined using medical spiral computer tomography principles.In all experimental stages,regions exists where the oil saturation decline is more than 10.0%.The shrinkage percentage is 20.70%in the horizontal well production stage.The oil saturation reduction in other parts is less than 10.0%,and there are regions where the oil saturation increases in the conventional water flooding stage.
文摘Heterogeneous reservoir characteristics for oilfield, choose HS-1 non-ionic surfactant and polymer formation in binary combination flooding system can significantly improve the rate of production of low permeability reservoir in heterogeneous reservoir. According to the core flooding experiment analyzed longitudinal heterogeneous models, single surfactant and a single polymer and polymer flooding of table binary complex drive effect. Studies show that binary combination flooding recovery effect is best, followed by polymer flooding, minimum of surfactant flooding, in heterogeneous reservoir.
基金Supported by the National Major Special Project of Oil and Gas During the 13th Five-Year Plan Period(NO.2016ZX05058-003-010)General Program of National Natural Science Foundation of China(NO.51574086)Postdoctoral Innovative Talent Support Program of China(NO.BX20190065)。
文摘Taking reservoir rocks and fluids of the Daqing,Dagang and Changqing oilfields as research objects,the EOR mechanisms and technical approach of polymer flooding were discussed.By comparing the displacement performances of ordinary polymer,glycerol,polymer in"sheet-net"structure and heterogeneous weak gel at the same viscosity and concentration,the relationship between the viscosity of polymer displacement agents and displacement performance was demonstrated,and the method of improving polymer flooding effect was worked out.The main mechanism of polymer flooding to increase oil recovery is the swept volume expansion of water injection due to polymer retention in porous media.The viscosity of polymer agents has no positive correlation with polymer flooding effect.Although polymer of"sheet-net"structure has strong capacity in increasing viscosity,it has poor compatibility with pore throat structure of reservoir rock,low injectivity and low shear resistance.Heterogeneous weak gel system has higher adsorption and capture capacity in porous media,which is easy to retain in porous media,and can effectively establish seepage resistance in high permeability layers(zones).Compared with polymer solutions with the same viscosity or concentration,it has stronger ability to expand swept volume.Long term injection of polymer flooding agents will inevitably lead to fluid entry profile reversal,and thus worsening of polymer flooding effect.Alternate injection of high retention and low or non-retention displacement agents can further improve the displacement effect of polymer flooding agents.
文摘An environmentally benign process was devel-oped for the transesterification of Jatropha curcas L. seed oil with methanol using artificial zeolites loaded with potassium acetate as a heterogeneous catalyst. After calcination for 5 h at 823 K, the catalyst loaded with 47 wt.% CH3COOK exhibited the highest efficiency and best catalytic activity. The easily prepared cata-lysts were characterized by means of X-ray dif-fraction and IR spectroscopy, as well as Hammett indicator titration. The results revealed a strong dependence of catalytic activity on ba-sicity. The optimum reaction conditions for transesterification of J. curcas oil were also in-vestigated. The methyl ester content in the bio-diesel product exceeded 91% after 4h reaction at reflux temperature in the presence of 2% solid catalyst and no water washing process is needed during workup.
文摘Energy obtained from a variety of non-renewable sources is considered unsustainable. Various fossil fuels, such as petroleum, coal, and natural gas, are among these sources. The combustion of fossil fuels resulted in the generation of greenhouse gases, which increased the amount of carbon dioxide in the atmosphere. Global warming and ozone layer degradation are the negative consequences. In a country like India, where consumable oils are still imported, it is sense to look at the possibility of using such unpalatable oils in CI engines that aren’t often utilized as cooking oil. Palm oil is a vegetable oil obtained from the monocarp of the oil palm’s crop. The main goal is to provide a low-cost, high-performance alternative to diesel. The possibility of palm oil as a realistic, modest, and effective hotspot for the generation of biodiesel is investigated in this research. The article is focused on the comparison of palm oil and diesel in terms of characteristics.
基金Supported by the National Natural Science Foundation of China (42072186)China National Oil and Gas Major Project (2016ZX05046-001)PetroChina Scientific Research and Technology Project (2021-DJ2203)。
文摘Based on the comparison of basic geological conditions and enrichment characteristics of shale oil plays, the heterogeneity of source and reservoir conditions and differential enrichment of medium-high maturity continental shale oil plays in China have been confirmed.(1) Compared with the homogeneous geological settings and wide distribution of marine shale oil strata in North America, the continental medium and high maturity shale oil plays in China are significantly different in geological conditions generally;continental multi-cyclic tectonic evolution forms multiple types of lake basins in multi-stages, providing sites for large-scale development of continental shale oil, and giving rise to large scale high-quality source rocks, multiple types of reservoirs, and diverse source-reservoir combinations with significant heterogeneity.(2) The differences in sedimentary water environments lead to the heterogeneity in lithology, lithofacies, and organic material types of source rocks;the differences in material source supply and sedimentary facies belt result in reservoirs of different lithologies, including argillaceous and transition rocks, and tight siltstone, and complex source-reservoir combination types.(3) The heterogeneity of the source rock controls the differentiation of hydrocarbon generation and expulsion, the diverse reservoir types make reservoir performance different and the source-reservoir configurations complex, and these two factors ultimately make the shale oil enrichment patterns different. Among them, the hydrocarbon generation and expulsion capacity of high-quality source rocks affect the degree of shale oil enrichment. Freshwater hydrocarbon source rocks with TOC larger than 2.5% and saline hydrocarbon source rocks with TOC of 2% to 10% have a high content of retained hydrocarbons and are favorable.(4) High-abundance organic shale is the basis for the enrichment of shale oil inside the source. In addition to being retained in shale, liquid hydrocarbons migrate along laminae, diagenetic fractures, and thin sandy layers, and then accumulate in laminae of argillaceous siltstone, siltstone, and argillaceous dolomite, and dolomitic siltstone suites, etc. with low organic matter abundance in the shale strata, resulting in differences in enrichment pattern.
基金Supported by the Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China(IRT0936)
文摘Waste cooking oil(WCO) is becoming the most promising alternative feedstock to produce biodiesel due to its low cost in China. In this study, NKC-9 ion-exchange resin and H-beta zeolite were selected as heterogeneous catalysts in the WCO esterification process and their esterification characteristics were compared by orthogonal experiments. NKC-9 resin showed higher activity and achieved a higher final conversion compared with H-beta zeolite under the same reaction conditions. Reusability experiments showed that NKC-9 resin still exhibited high activity after 5 runs. The effects of the mole ratio of alcohol to oil, reaction time, reaction temperature and the catalyst dose were investigated by multifactor orthogonal analysis. The influence of the free fatty acid(FFA) content was also investigated, and the result showed that the esterification rate could be as high as 98.4% when the FFA content was 6.3wt%.
文摘During the displacement of water plugging with binary flooding in internally heterogeneous reservoirs,it is essential to understand the distributions of remaining oil as well as the oil displacement mechanisms at different stages.In this study,two types of internally heterogeneous systems,i.e.,vertical and horizontal wells are investigated experimentally through a microscopic approach.The results show that plugging agent types have a greater impact on oil recovery than well types,and foam injection can enhance oil recovery more effectively than gel injection.Additionally,the injection sequence of plugging agents significantly affects oil displacement efficiency.Injecting gel after foam is more beneficial.According to the present results,the main formation mechanisms of remaining oil in each displacement stage are influenced by:capillary force,viscous force,inertial force,shear force,microscopic fingering&channeling.
基金Supported by the China National Science and Technology Major Project(2017ZX05009-005)the National Natural Science Foundation of China(51674271)
文摘Waterflooding experiments were performed using Micro-CT on four cores of different pore structures from Donghe sandstone reservoirs in the Tarim Basin. The water, oil and grains were accurately separated by the advanced image processing technology, the pore network model was established, and parameters such as the number of throats and the throat size distribution were calculated to characterize the microscopic heterogeneity of pore structure, the flow of oil phase during displacement, and the morphology and distribution of remaining oil after displacement. The cores with the same macroscopic porosity-permeability have great differences in microscopic heterogeneity of pore structure. Both macro porosity-permeability and micro heterogeneity of pore structure have an influence on the migration of oil phase and the morphology and distribution of remaining oil. When the heterogeneity is strong, the water phase will preferentially flow through the dominant paths and the remaining oil clusters will be formed in the small pores. The more the number of oil clusters(droplets) formed during displacement process, the smaller the average volume of cluster is, and the remaining oil is dominated by the cluster continuous phase with high saturation. The weaker the heterogeneity, the higher the pore sweep efficiency is, and the remaining oil clusters are mainly trapped in the form of non-continuous phase. The distribution and morphology of micro remaining oil are related to the absolute permeability, capillary number and micro-heterogeneity. So, the identification plate of microscopic residual oil continuity distribution established on this basis can describe the relationship between these three factors and distribution of remaining oil and identify the continuity of the remaining oil distribution accurately.
基金This project was financially supported by the National Natural Science Foundation of China (Grant No. 40502013)
文摘The Linnan subsag is the main oil producer of the Linpan oil zone. Based on the oil group composition,gas chromatography data and biomarker analysis,it was indicated that crude oils from different oilfields varied greatly in group composition and showed obvious heterogeneities in the aspects of precursor type,crude oil maturity and hydrocarbon depositional environment. According to the characteristics of source rocks,three oil populations can be distinguished,i.e.,the southern,northern and transitional oil populations. Furthermore,on the basis of post-reservoir reworking processes,the medium conditions of hydrocarbon-generating environment and differences in maturity,six oil families and twelve sub-families were distinquished. An integrated study suggested that the fac-tors leading to such heterogeneities in crude oil composition mainly include different source rocks,multi-stage oil/gas charging,geo-chromatographic effects during oil/gas migration,reservoir heterogeneities and various post-reservoir secondary alterations.
基金supported by the National Research and Development Fund entitled“High Precision Characterization Technology of Natural Gas Hydrates Reservoirs”(2017YFC0307406)the projects entitled“Integrated Observation Data Integration and Application Service of Natural Resource Elements”(DD20208067)+2 种基金“Comprehensive geological survey of coastal zone and reef in the Northern Jiaodong”(ZD20220604)initiated by the China Geological Surveythe project entitled“Study on Hydrocarbon Accumulation Failure and Fluid Evolution Reduction of the Permian Reservoir in the Laoshan Uplift,South Yellow Sea”(42076220)“Temporal and Spatial Distribution Characteristics and Provenance of Two Stages Paleo-deltas on the Outer Shelf in the North of the East China Sea since Late Pleistocene”(41706069)organized by the National Natural Science Foundation of China。
文摘Drilling results suggest that the thickness of natural gas hydrates(NGHs)in the Shenhu Area,South China Sea(SCS)are spatially heterogenous,making it difficult to accurately assess the NGHs resources in this area.In the case that free gas exists beneath hydrate deposits,the frequency of the hydrate deposits will be noticeably attenuated,with the attenuation degree mainly affected by pore development and free gas content.Therefore,the frequency can be used as an important attribute to identify hydrate reservoirs.Based on the time-frequency characteristics of deposits,this study predicted the spatial distribution of hydrates in this area using the frequency division inversion method as follows.Firstly,the support vector machine(SVM)method was employed to study the amplitude versus frequency(AVF)response based on seismic and well logging data.Afterward,the AVF response was introduced as independent information to establish the nonlinear relationship between logging data and seismic waveform.Then,the full frequency band information of the seismic data was fully utilized to obtain the results of frequency division inversion.The inversion results can effectively broaden the frequency band,reflect the NGHs distribution,and reveal the NGHs reservoirs of two types,namely the fluid migration pathway type and the in situ self-generation self-storage diffusion type.Moreover,the inversion results well coincide with the drilling results.Therefore,it is feasible to use the frequency division inversion to predict the spatial distribution of heterogeneous NGHs reservoirs,which facilitates the optimization of favorable drilling targets and is crucial to the resource potential assessment of NGHs.