Pub Date : 2023-05-16DOI: 10.1177/01445987231173091
W. Liu, Jiasheng Fu, Chunjing Tang, Xinyu Huang, Ting Sun
ROP (Rate of Penetration) is a comprehensive indicator of the rock drilling process and how efficiently predicting drilling rates is important to optimize resource allocation, reduce drilling costs and manage drilling hazards. However, the traditional model is difficult to consider the multiple factors, which makes the prediction accuracy difficult to meet the real drilling requirements. In order to provide efficient, accurate and comprehensive information for drilling operation decision-making, this study evaluated the applicability of four typical regression algorithms based on machine learning for predicting pore pressure in Troll West field, namely SVR (Support Vector Regression), Linear regression, Regression Tree and Gradient Boosting regression. These methods allow more parameters input. By comparing the prediction results of these typical regression algorithms based on R2(R-Square), explained variance, mean absolute error, mean squared error, median absolute error and other performance indicators, it was found that each method predicted different results, among which Gradient Boosting regression has the best results, their prediction accuracy is high and the error is very low. The prediction accuracy of these methods is positively correlated with the proportion of the training data set. With the increase of logging features, the prediction accuracy is gradually improved. In the prediction of adjacent wells, the ROP prediction methods can achieve a certain prediction effect, which shows that this method is suitable for ROP prediction in Troll West field.
{"title":"Real-time prediction of multivariate ROP (rate of penetration) based on machine learning regression algorithms: Algorithm comparison, model evaluation and parameter analysis","authors":"W. Liu, Jiasheng Fu, Chunjing Tang, Xinyu Huang, Ting Sun","doi":"10.1177/01445987231173091","DOIUrl":"https://doi.org/10.1177/01445987231173091","url":null,"abstract":"ROP (Rate of Penetration) is a comprehensive indicator of the rock drilling process and how efficiently predicting drilling rates is important to optimize resource allocation, reduce drilling costs and manage drilling hazards. However, the traditional model is difficult to consider the multiple factors, which makes the prediction accuracy difficult to meet the real drilling requirements. In order to provide efficient, accurate and comprehensive information for drilling operation decision-making, this study evaluated the applicability of four typical regression algorithms based on machine learning for predicting pore pressure in Troll West field, namely SVR (Support Vector Regression), Linear regression, Regression Tree and Gradient Boosting regression. These methods allow more parameters input. By comparing the prediction results of these typical regression algorithms based on R2(R-Square), explained variance, mean absolute error, mean squared error, median absolute error and other performance indicators, it was found that each method predicted different results, among which Gradient Boosting regression has the best results, their prediction accuracy is high and the error is very low. The prediction accuracy of these methods is positively correlated with the proportion of the training data set. With the increase of logging features, the prediction accuracy is gradually improved. In the prediction of adjacent wells, the ROP prediction methods can achieve a certain prediction effect, which shows that this method is suitable for ROP prediction in Troll West field.","PeriodicalId":11606,"journal":{"name":"Energy Exploration & Exploitation","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42706199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Reservoir pore characteristics are an important part of shale gas reservoir capacity evaluation. Compared with Marine shale, the study of coal measure shale is relatively backward in China. In order to deeply analyze the reservoir properties of coal measure shale gas and give priority to favorable reservoirs, the pore structure characteristics of shale in coal measures from the Shanxi Formation of Lower Permian in Huainan Coalfield of China were investigated in this study. The pore size distribution, specific surface area (SSA), and pore volume (PV) were obtained. The BET surface area and PVs are inconsistent with the variability in total organic content (TOC) and composition of the samples. There are unobvious negative correlations between PV, SSA, and TOC for the samples in this study. However, the contribution of clay minerals to PV and SSA seems to be positive, especially for the mixed-layer minerals of illite and smectite.
{"title":"Pore structure characteristics of shale in coal-bearing strata: In the case of the Shanxi formation of lower Permian in Huainan coalfield in China","authors":"Jingfen Yang, Hongjie Xu, Sheng Xue, Hai Ding, Huihu Liu, Jinlong Jia, Huihuang Fang, Kunzhen Zhang","doi":"10.1177/01445987231175572","DOIUrl":"https://doi.org/10.1177/01445987231175572","url":null,"abstract":"Reservoir pore characteristics are an important part of shale gas reservoir capacity evaluation. Compared with Marine shale, the study of coal measure shale is relatively backward in China. In order to deeply analyze the reservoir properties of coal measure shale gas and give priority to favorable reservoirs, the pore structure characteristics of shale in coal measures from the Shanxi Formation of Lower Permian in Huainan Coalfield of China were investigated in this study. The pore size distribution, specific surface area (SSA), and pore volume (PV) were obtained. The BET surface area and PVs are inconsistent with the variability in total organic content (TOC) and composition of the samples. There are unobvious negative correlations between PV, SSA, and TOC for the samples in this study. However, the contribution of clay minerals to PV and SSA seems to be positive, especially for the mixed-layer minerals of illite and smectite.","PeriodicalId":11606,"journal":{"name":"Energy Exploration & Exploitation","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41726612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mine water disaster is closely related to the geological structure of the mine. A scientific evaluation of the complexity of the minefield structure can greatly contribute to mining safety. In this study, we optimized the fault impact index in the study area and proposed an improved local linear embedding (LLE) algorithm by investigating the Shengquan coal mine. We analyzed the fault formation age and connectivity between faults in the study area, combined with topology theory, and based on previous studies. The mechanical properties of faults and the influence of small faults on the strata can be combined to derive a quantitative evaluation model of the structural complexity of mines. Based on the evaluation model, the study area was divided into a simple structural area, a medium structural area, and a complex structural area. By comparing the location of water inrush points in recent years with the three-dimensional high-density electrical exploration of the 21,304 working face, the effectiveness and rationality of structural complexity zoning were determined.
{"title":"Quantitative evaluation of structural complexity in Shengquan minefield based on improved local linear embedding algorithm","authors":"Peihe Zhai, Yuxiang Liu, Tianhao Liu, Longqing Shi, Changxin Lv","doi":"10.1177/01445987231157124","DOIUrl":"https://doi.org/10.1177/01445987231157124","url":null,"abstract":"Mine water disaster is closely related to the geological structure of the mine. A scientific evaluation of the complexity of the minefield structure can greatly contribute to mining safety. In this study, we optimized the fault impact index in the study area and proposed an improved local linear embedding (LLE) algorithm by investigating the Shengquan coal mine. We analyzed the fault formation age and connectivity between faults in the study area, combined with topology theory, and based on previous studies. The mechanical properties of faults and the influence of small faults on the strata can be combined to derive a quantitative evaluation model of the structural complexity of mines. Based on the evaluation model, the study area was divided into a simple structural area, a medium structural area, and a complex structural area. By comparing the location of water inrush points in recent years with the three-dimensional high-density electrical exploration of the 21,304 working face, the effectiveness and rationality of structural complexity zoning were determined.","PeriodicalId":11606,"journal":{"name":"Energy Exploration & Exploitation","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47272004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-09DOI: 10.1177/01445987231174767
Faouzan Abdulaziz Alfaoyzan, Radwan A. Almasri
One of the primary things damaging the environment is the use of energy. In the Kingdom of Saudi Arabia (KSA), electricity is the main source of energy in educational buildings. To conserve the environment, significant efforts are now being made to reduce energy use in general and electricity use in particular. To be sustainable, it is also vital to research the possibilities of employing solar energy in the higher education sector since it is also accessible in the KSA. The main motives behind this study are the low prices of photovoltaic (PV) solar systems globally and the existence of a new government system to benefit from solar energy in the KSA. The utilization of PV solar energy at Sulaiman Al-Rajhi University in the Qassim region was examined in this article. Two scenarios were considered: scenario 1, in which the entire roof of the buildings is covered by a PV system, and scenario 2, for securing electricity so that it is a nearly zero-bill campus (nZBC). The yield factors calculated for scenarios 1 and 2 are 1896 and 1922 kWh/kWp, respectively, while the capacity factor is 21.6% for scenario 1 and 21.9% for scenario 2. For scenarios 1 and 2, the systems produce 2,160,181 and 10,199,253 kWh of electrical energy annually, respectively. The production in the second scenario is about 113% of the load to reach an nZBC, compared to the first scenario's coverage of about 24% of the load. The levelized cost of energy was found to be between 0.026 and 0.028 $/kWh, with a simple payback period of 10 years for scenario 1 and 8.1 years for scenario 2. Additionally, the proposed systems’ environmental benefits were noted.
{"title":"Utilizing solar photovoltaic systems in educational facilities to achieve a zero bill campus: The Sulaiman Al-Rajhi University case","authors":"Faouzan Abdulaziz Alfaoyzan, Radwan A. Almasri","doi":"10.1177/01445987231174767","DOIUrl":"https://doi.org/10.1177/01445987231174767","url":null,"abstract":"One of the primary things damaging the environment is the use of energy. In the Kingdom of Saudi Arabia (KSA), electricity is the main source of energy in educational buildings. To conserve the environment, significant efforts are now being made to reduce energy use in general and electricity use in particular. To be sustainable, it is also vital to research the possibilities of employing solar energy in the higher education sector since it is also accessible in the KSA. The main motives behind this study are the low prices of photovoltaic (PV) solar systems globally and the existence of a new government system to benefit from solar energy in the KSA. The utilization of PV solar energy at Sulaiman Al-Rajhi University in the Qassim region was examined in this article. Two scenarios were considered: scenario 1, in which the entire roof of the buildings is covered by a PV system, and scenario 2, for securing electricity so that it is a nearly zero-bill campus (nZBC). The yield factors calculated for scenarios 1 and 2 are 1896 and 1922 kWh/kWp, respectively, while the capacity factor is 21.6% for scenario 1 and 21.9% for scenario 2. For scenarios 1 and 2, the systems produce 2,160,181 and 10,199,253 kWh of electrical energy annually, respectively. The production in the second scenario is about 113% of the load to reach an nZBC, compared to the first scenario's coverage of about 24% of the load. The levelized cost of energy was found to be between 0.026 and 0.028 $/kWh, with a simple payback period of 10 years for scenario 1 and 8.1 years for scenario 2. Additionally, the proposed systems’ environmental benefits were noted.","PeriodicalId":11606,"journal":{"name":"Energy Exploration & Exploitation","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48317543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-08DOI: 10.1177/01445987231173083
Dailu Zhang, Hongbing Zhang, Q. Ren, Xiang Zhao
The analysis of drop formation and the transition between separated and non-separated oil–water flows enables us to better regulate flow parameters and pipe inclination angle, which is of great significance for improving the efficiency of oil transportation. Previous studies mainly carried out qualitative analysis through experiments and studied the transition between separated flows, very few studies are conducted on the transition between separated flow and dual continuous flow or intermittent flow. In addition, the influence of pipe inclination angle was not considered in the study of drop formation, which results in inadequate force analysis of drop. This article presents the use of dimensionless numbers to predict the transition between separated flow and dual continuous flow or intermittent flow. The relation expression between dimensionless numbers is obtained by regression of experimental data. The critical values of flow parameters and pipe inclination angle can be calculated by the relation expression between dimensionless numbers and flow parameters. In addition, this article proposes a three-dimensional interfacial wave shear deformation mechanism by adding volume forces to the force analysis for the possible inclined pipe. The prediction equation is obtained and the critical value of flow parameters and pipe inclination angle for drop formation can be calculated, which are in good agreement with the experimental data.
{"title":"Mechanism of transition between separated and non-separated oil-water flows in inclined pipe","authors":"Dailu Zhang, Hongbing Zhang, Q. Ren, Xiang Zhao","doi":"10.1177/01445987231173083","DOIUrl":"https://doi.org/10.1177/01445987231173083","url":null,"abstract":"The analysis of drop formation and the transition between separated and non-separated oil–water flows enables us to better regulate flow parameters and pipe inclination angle, which is of great significance for improving the efficiency of oil transportation. Previous studies mainly carried out qualitative analysis through experiments and studied the transition between separated flows, very few studies are conducted on the transition between separated flow and dual continuous flow or intermittent flow. In addition, the influence of pipe inclination angle was not considered in the study of drop formation, which results in inadequate force analysis of drop. This article presents the use of dimensionless numbers to predict the transition between separated flow and dual continuous flow or intermittent flow. The relation expression between dimensionless numbers is obtained by regression of experimental data. The critical values of flow parameters and pipe inclination angle can be calculated by the relation expression between dimensionless numbers and flow parameters. In addition, this article proposes a three-dimensional interfacial wave shear deformation mechanism by adding volume forces to the force analysis for the possible inclined pipe. The prediction equation is obtained and the critical value of flow parameters and pipe inclination angle for drop formation can be calculated, which are in good agreement with the experimental data.","PeriodicalId":11606,"journal":{"name":"Energy Exploration & Exploitation","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45722972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lacustrine shale oil has the potential to lead the development of China's oil and gas industry. By integrating scanning electron microscopy, low-temperature CO2 and N2 adsorption, high-pressure mercury intrusion, and nuclear magnetic resonance with centrifugation at different speeds, the pore system and pore fluid distribution of Da’anzhai Member lacustrine shale in the Sichuan Basin are studied. The results show that: (1) The reservoir space is mainly inorganic pores and micro-fractures. Nano-micron scale pores are commonly found and widely distributed in the Da’anzhai shale with multiple peaks of 28 nm, 200 nm, 900 nm, and 3.5 µm. The total pore volume ranges from 0.00849 to 0.02808 cm³/g, and the pores ranging from 100 nm to 1000 nm are the main contributors to total pore volume. (2) Pore fluid can be divided into movable oil, bound oil, and adsorption oil. The proportion of movable oil, bound oil, and adsorbed oil is 21.4%, 12.4%, and 66.2% in Da’anzhai shale, respectively. Movable oil mainly occurs in pores larger than 350 nm, bound oil is 30–350 nm, while adsorbed oil mainly exists in pores below 30 nm. (3) The higher the total organic carbon content and clay minerals content, the smaller the pore size, resulting in the low content of movable oil. The higher the content of brittle minerals such as quartz, the better the development of intergranular pores and microfractures, and the higher the content of movable oil. Through the grading evaluation of shale pore structure and pore fluid, it is conducive to guide the exploration and development of Da’anzhai shale oil, which has important theoretical and practical significance.
{"title":"Pore system classification of Jurassic Da’anzhai Member Lacustrine Shale: Insight from pore fluid distribution","authors":"Guangyin Cai, Yifan Gu, Yonghong Fu, Yuqiang Jiang, Z. Wei, Zimeng Wang, Ruobing Liu, Xiaoxue Qiu","doi":"10.1177/01445987231154613","DOIUrl":"https://doi.org/10.1177/01445987231154613","url":null,"abstract":"Lacustrine shale oil has the potential to lead the development of China's oil and gas industry. By integrating scanning electron microscopy, low-temperature CO2 and N2 adsorption, high-pressure mercury intrusion, and nuclear magnetic resonance with centrifugation at different speeds, the pore system and pore fluid distribution of Da’anzhai Member lacustrine shale in the Sichuan Basin are studied. The results show that: (1) The reservoir space is mainly inorganic pores and micro-fractures. Nano-micron scale pores are commonly found and widely distributed in the Da’anzhai shale with multiple peaks of 28 nm, 200 nm, 900 nm, and 3.5 µm. The total pore volume ranges from 0.00849 to 0.02808 cm³/g, and the pores ranging from 100 nm to 1000 nm are the main contributors to total pore volume. (2) Pore fluid can be divided into movable oil, bound oil, and adsorption oil. The proportion of movable oil, bound oil, and adsorbed oil is 21.4%, 12.4%, and 66.2% in Da’anzhai shale, respectively. Movable oil mainly occurs in pores larger than 350 nm, bound oil is 30–350 nm, while adsorbed oil mainly exists in pores below 30 nm. (3) The higher the total organic carbon content and clay minerals content, the smaller the pore size, resulting in the low content of movable oil. The higher the content of brittle minerals such as quartz, the better the development of intergranular pores and microfractures, and the higher the content of movable oil. Through the grading evaluation of shale pore structure and pore fluid, it is conducive to guide the exploration and development of Da’anzhai shale oil, which has important theoretical and practical significance.","PeriodicalId":11606,"journal":{"name":"Energy Exploration & Exploitation","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"65449490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-01DOI: 10.1177/01445987231155980
Siyu Li, Kai Bian, Guilei Han, Bo Liu, Xi Chen, Hui Sun, Hao Yang, Junbin Chang
Water inrush from coal floor is a gradual process from generation, and development to disaster. In this process, the geophysical information received by the rock mass will show measurable characteristics of the sudden, and the occurrence of water inrush is the inevitable reflection of various characteristics of the sudden in the limit state. In order to study the early warning information before water inrush in working face, based on the fluid-solid coupling theory, similar simulation test and FLAC3D simulation were used to reproduce the water inrush process of the floor fracture structure, to clarify the difference of response characteristics of each physical quantity before and after water inrush, and to calculate the weight value of different physical quantities in the water inrush process combined with entropy method. The results show that when the working face is gradually approaching the penetrating fault, the stress at the water inrush position of the floor rock layer decreases sharply, and the step jump change occurs after reaching the minimum peak value. The water flow shows a stable increase–sudden increase process. Water inrush through fault location water flow presents increasing—stability—the changing process of surge, water pressure appears cliff-like drop. In the sub-emergent stage when water inrush is about to occur in the working face, the variation range of stress and water pressure at the position of water inrush is more intense. The increase rate of stress at the position of water inrush in the floor rock layer increases sharply and reaches the peak value in a short time, while the increase rate of water pressure at the position of water inrush through the fault decreases.
{"title":"Study on water inrush warning information of coal seam floor fault structure","authors":"Siyu Li, Kai Bian, Guilei Han, Bo Liu, Xi Chen, Hui Sun, Hao Yang, Junbin Chang","doi":"10.1177/01445987231155980","DOIUrl":"https://doi.org/10.1177/01445987231155980","url":null,"abstract":"Water inrush from coal floor is a gradual process from generation, and development to disaster. In this process, the geophysical information received by the rock mass will show measurable characteristics of the sudden, and the occurrence of water inrush is the inevitable reflection of various characteristics of the sudden in the limit state. In order to study the early warning information before water inrush in working face, based on the fluid-solid coupling theory, similar simulation test and FLAC3D simulation were used to reproduce the water inrush process of the floor fracture structure, to clarify the difference of response characteristics of each physical quantity before and after water inrush, and to calculate the weight value of different physical quantities in the water inrush process combined with entropy method. The results show that when the working face is gradually approaching the penetrating fault, the stress at the water inrush position of the floor rock layer decreases sharply, and the step jump change occurs after reaching the minimum peak value. The water flow shows a stable increase–sudden increase process. Water inrush through fault location water flow presents increasing—stability—the changing process of surge, water pressure appears cliff-like drop. In the sub-emergent stage when water inrush is about to occur in the working face, the variation range of stress and water pressure at the position of water inrush is more intense. The increase rate of stress at the position of water inrush in the floor rock layer increases sharply and reaches the peak value in a short time, while the increase rate of water pressure at the position of water inrush through the fault decreases.","PeriodicalId":11606,"journal":{"name":"Energy Exploration & Exploitation","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72472039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-25DOI: 10.1177/01445987231171407
Minglong Li, X. Tan, Gaoxiang Wang, Yanjun Li, Qiang Xu, Jian Zheng, Yang Yang, Xiaoliang Bai, Yubing Ji
Based on the identification of visual kerogen assessment, a subdivision method of organic matter types was proposed. Combined with GR curve, the distribution was further studied, the relationship between shale reservoir parameters and organic matter types was analyzed, and the significance was discussed. The results show that the kerogen types of organic rich shale in the lower part of Wufeng-Longmaxi Formation in the south of the Sichuan Basin are mainly of type I, II1a and II1b, while type II2 and type III are not developed. In Wufeng Formation, the shale organic matter is mainly of type II1a and II1b. From Long111 to Long114, the shale displays a trend of “Type I-II1b-II1a-II1b”. Type I was characterized by higher TOC, porosity and gas bearing capacity of shale reservoirs than the other organic matter. The reservoir parameter of type II1a was better than type II1b, indicating that the organic matter type control on the quality of shale reservoirs. Type difference is closely related to the bio-precursors component, among which type I and type II1a are related to the content of planktonic algae, while type II1b is related to the content of benthic algae. This study provides a good reference for the subdivision of marine shale organic matter types and the evaluation and prediction of gas bearing properties.
{"title":"Differences of Organic Matter Types of High Maturity Marine Organic-Rich Shale from Wufeng-Longmaxi Formation: Implication for Shale Gas “Sweet Spots” Prediction","authors":"Minglong Li, X. Tan, Gaoxiang Wang, Yanjun Li, Qiang Xu, Jian Zheng, Yang Yang, Xiaoliang Bai, Yubing Ji","doi":"10.1177/01445987231171407","DOIUrl":"https://doi.org/10.1177/01445987231171407","url":null,"abstract":"Based on the identification of visual kerogen assessment, a subdivision method of organic matter types was proposed. Combined with GR curve, the distribution was further studied, the relationship between shale reservoir parameters and organic matter types was analyzed, and the significance was discussed. The results show that the kerogen types of organic rich shale in the lower part of Wufeng-Longmaxi Formation in the south of the Sichuan Basin are mainly of type I, II1a and II1b, while type II2 and type III are not developed. In Wufeng Formation, the shale organic matter is mainly of type II1a and II1b. From Long111 to Long114, the shale displays a trend of “Type I-II1b-II1a-II1b”. Type I was characterized by higher TOC, porosity and gas bearing capacity of shale reservoirs than the other organic matter. The reservoir parameter of type II1a was better than type II1b, indicating that the organic matter type control on the quality of shale reservoirs. Type difference is closely related to the bio-precursors component, among which type I and type II1a are related to the content of planktonic algae, while type II1b is related to the content of benthic algae. This study provides a good reference for the subdivision of marine shale organic matter types and the evaluation and prediction of gas bearing properties.","PeriodicalId":11606,"journal":{"name":"Energy Exploration & Exploitation","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46533919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-25DOI: 10.1177/01445987231171409
Jinzhu Hu, Zimin Ma, Pengfei Guo, Yunjin Hu
During the application of gob-side entry retaining by roof cutting in inclined coal seams, the boundary conditions of the main roof in the goaf will change, resulting in the special characteristics of its fracture evolution. This article established a main roof elastic mechanics model through theoretical analysis and obtained the stress expression of any point on the main roof, analyzed the stress distribution characteristics and fracture evolution law of the main roof, finally, and revealed the unloading mechanism of the overburden in the cutting roof of goaf by combining with field mining pressure data. The results show that the stress value on the main roof is related to the dip angle, the poison's ratio, and the geometry parameters of the working face. The main roof stress presented an asymmetric distribution in the inclined direction. The fracture mode of the main roof is the “U-Y” mode under the first weighting and the “L-Y” mode under periodic breakage. The pressure on the upper part of the working face increased, while the lower part decreased according to field mining pressure data. There are two reasons for the reduction of pressure in the lower part of the working face, on the one hand, the reduction of the area of the key block A leads to a decrease in load, on the other hand, the gangue filling and supporting effect of the lower part of the goaf. The surrounding rock of the gob-side entry is not obviously affected by the dynamic pressure, and the deformation is small, achieving a good retaining effect.
{"title":"Fracture evolution of the main roof in gob-side entry retaining by roof cutting of an inclined coal seam","authors":"Jinzhu Hu, Zimin Ma, Pengfei Guo, Yunjin Hu","doi":"10.1177/01445987231171409","DOIUrl":"https://doi.org/10.1177/01445987231171409","url":null,"abstract":"During the application of gob-side entry retaining by roof cutting in inclined coal seams, the boundary conditions of the main roof in the goaf will change, resulting in the special characteristics of its fracture evolution. This article established a main roof elastic mechanics model through theoretical analysis and obtained the stress expression of any point on the main roof, analyzed the stress distribution characteristics and fracture evolution law of the main roof, finally, and revealed the unloading mechanism of the overburden in the cutting roof of goaf by combining with field mining pressure data. The results show that the stress value on the main roof is related to the dip angle, the poison's ratio, and the geometry parameters of the working face. The main roof stress presented an asymmetric distribution in the inclined direction. The fracture mode of the main roof is the “U-Y” mode under the first weighting and the “L-Y” mode under periodic breakage. The pressure on the upper part of the working face increased, while the lower part decreased according to field mining pressure data. There are two reasons for the reduction of pressure in the lower part of the working face, on the one hand, the reduction of the area of the key block A leads to a decrease in load, on the other hand, the gangue filling and supporting effect of the lower part of the goaf. The surrounding rock of the gob-side entry is not obviously affected by the dynamic pressure, and the deformation is small, achieving a good retaining effect.","PeriodicalId":11606,"journal":{"name":"Energy Exploration & Exploitation","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46557177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-25DOI: 10.1177/01445987231171274
Feng Guo, Xiaoxia Peng, Xuqing Ma, Haonan Wang
Clarifying the main controlling factors of reservoirs and their oil-bearing potential is vital for predicting tight sandstone reservoirs. The Chang 8 reservoir in the southwest of Ordos Basin is a typical tight sandstone reservoir and is widely distributed. Observation description and sampling analysis of cores, the grain size analysis, casting thin section, scanning electron microscope, mercury pressure, nuclear magnetic resonance, and conventional physical analysis are used to clarify the main controlling factors and oil-bearing potential characteristics of the Chang 8 reservoir in southwest Ordos Basin. The results show that delta front subfacies are mainly developed in Chang 8 member, including distributary channel, natural dike, estuary bar and distributary bay. The main rock type of reservoir is lithic feldspathic sandstone, followed by feldspathic lithic sandstone. The types of reservoir space are mainly intergranular pores and intragranular dissolved pores, with a small amount of clay-related pores and micro-fractures. The average porosity and permeability of the reservoir are 11.67% and 0.52 × 10−3μm2, respectively. The reservoirs with high oil saturation are mainly distributary channels and thicker mouth bar sand bodies. Compaction is the main factor of reservoir compaction (porosity loss rate is 55.73%), followed by cementation (porosity loss rate is 29.23%). The favorable diagenesis is the dissolution of feldspar grains and some cement. The Chang 8 tight reservoir contains various nano-scale pore-throat. For tight reservoirs with similar physical properties, the pore-throat structure controls the oil saturation of the tight reservoir. Favorable conditions for tight sandstone reservoirs oil saturation include favorable sedimentary environment (distributary channel or thick mouth bar) and suitable microscopic pore characteristics.
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