Determining the process of densification and tectonic evolution of tight sandstone can help to understand the distribution of reservoirs and find relatively high-permeability areas.Based on integrated approaches of th...Determining the process of densification and tectonic evolution of tight sandstone can help to understand the distribution of reservoirs and find relatively high-permeability areas.Based on integrated approaches of thin section,scanning electron microscopy(SEM),cathode luminescence(CL),nuclear magnetic resonance(NMR),X-ray diffraction(XRD),N2 porosity and permeability,micro-resistivity imaging log(MIL)and three-dimensional seismic data analysis,this work discussed the reservoir characteristics of the member 8 of the Permian Xiashihezi Formation(He 8 sandstones)in the Linxing area of eastern Ordos Basin,determined the factors affecting reservoir quality,and revealed the formation mechanism of relatively high-permeability areas.The results show that the He 8 sandstones in the Linxing area are mainly composed of feldspathic litharenites,and are typical tight sandstones(with porosity<10%and permeability<1 mD accounting for 80.3%of the total samples).Rapid burial is the main reason for reservoir densification,which resulted in 61%loss of the primary porosity.In this process,quartz protected the original porosity by resisting compaction.The cementation(including carbonate,clay mineral and siliceous cementation)further densified the sandstone reservoirs,reducing the primary porosity with an average value of 28%.The calcite formed in the eodiagenesis occupied intergranular pores and affected the formation of the secondary pores by preventing the later fluid intrusion,and the Fe-calcite formed in the mesodiagenetic stage densified the sandstones further by filling the residual intergranular pores.The clay minerals show negative effects on reservoir quality,however,the chlorite coatings protected the original porosity by preventing the overgrowth of quartz.The dissolution of feldspars provides extensive intergranular pores which constitute the main pore type,and improves the reservoir quality.The tectonic movements play an important role in improving the reservoir quality.The current tectonic traces of the study area are mainly controlled by the Himalayan movement,and the high-permeability reservoirs are mainly distributed in the anticline areas.Additionally,the improvement degree(by tectonic movements)of reservoir quality is partly controlled by the original composition of the sandstones.Thus,the selection of potential tight gas well locations in the study area should be focused on the anticline areas with relatively good original reservoir quality.And the phenomena can be referenced for other fluvial tight sandstone basins worldwide.展开更多
Gastroesophageal reflux disease has an increasing incidence and prevalence worldwide.A significant proportion of patients have a suboptimal response to proton pump inhibitors or are unwilling to take lifelong medicati...Gastroesophageal reflux disease has an increasing incidence and prevalence worldwide.A significant proportion of patients have a suboptimal response to proton pump inhibitors or are unwilling to take lifelong medication due to concerns about long-term adverse effects.Endoscopic anti-reflux therapies offer a minimally invasive option for patients unwilling to undergo surgical treatment or take lifelong medication.The best candidates are those with a good response to proton pump inhibitors and without a significant sliding hiatal hernia.Transoral incisionless fundoplication and nonablative radiofrequency are the techniques with the largest body of evidence and that have been tested in several randomized clinical trials.Band-assisted ligation techniques,anti-reflux mucosectomy,antireflux mucosal ablation,and new plication devices have yielded promising results in recent noncontrolled studies.Nonetheless,the role of endoscopic procedures remains controversial due to limited long-term and comparative data,and no consensus exists in current clinical guidelines.This review provides an updated summary focused on the patient selection,technical details,clinical success,and safety of current and future endoscopic anti-reflux techniques.展开更多
AIM: With the availability of a minimally invasive approach, anti-reflux surgery has recently experienced a renaissance as a cost-effective alternative to life-long medical treatment in patients with gastroesophageal ...AIM: With the availability of a minimally invasive approach, anti-reflux surgery has recently experienced a renaissance as a cost-effective alternative to life-long medical treatment in patients with gastroesophageal reflux disease (GERD). We are not aware of the fact whether reflux episodes causing complaints for a long time i.e., at least for one year are associated with metabolic changes in the lower esophageal sphincter, and if so, whether these may influence functional results achieved after anti-reflux surgery. METHODS: Between 1 January 2001 and 31 December 2002 we performed anti-reflux surgery on 79 patients. Muscle samples were taken from the lower esophageal sphincter (LES) in 33 patients during anti-reflux surgery. Inclusion criteria were: LES resting pressure below 10 mmHg and a marked, pH proven acid exposure to the esophagus of at least one year's duration, causing subjective complaints and requiring continuous proton pump inhibitor treatment. Control samples were obtained from muscle tissue in the gastroesophageal junction that had been removed from 17 patients undergoing gastric or esophageal resection. Metabolic and lysosomal enzyme activities and special protein concentrations 16 parameters in total were evaluated in tissue taken from control specimens and tissue taken from patients with GERD. The biochemical parameters of these intra-operative biopsies were used to correlate the results of anti-reflux operations (Visick Ⅰ and Ⅱ-Ⅲ). RESULTS: In the reflux-type muscle, we found a significant increase of the energy-enzyme activities e.g., creatine kinase, lactate dehydrogenase, β-hydroxybutyrate dehydrogenase, and aspartate aminotransaminase-. The concentration of the structural protein S-100 and the myofibrillar protein troponin Ⅰ were also significantly increased. Among lysosomal enzymes, we found that the activities of cathepsin B, tripeptidyl-peptidase Ⅰ, dipeptidyl-peptidase Ⅱ, β-hexosaminidase B, β-mannosidase and β-galactosidase were significantly decreased as compared to the control LES muscles. By analyzing the activity values of the 9 patients in Visick groups Ⅱ and Ⅲ at two months post-surgery, we found a significant increase in the activity of the so-called energy-enzyme values and in the concentration of structural and myofibrillar proteins as compared to the rest of the reflux patients. CONCLUSION: Our results call attention to the metabolic changes that occurred in the LES muscles of reflux patients. The developing hypertrophy-like changes of LES muscles may be a reason for complaints after anti-reflux surgery, which consisted mainly of reports of persisting dysphagia.展开更多
Endoscopic anti-reflux treatment is emerging as a new option for gastroesophageal reflux disease(GERD)treatment in patients with the same indications as for laparoscopic fundoplication.There are many techniques,the fi...Endoscopic anti-reflux treatment is emerging as a new option for gastroesophageal reflux disease(GERD)treatment in patients with the same indications as for laparoscopic fundoplication.There are many techniques,the first of which are transoral incisionless fundoplication(TIF)and nonablative radio-frequency(STRETTA)that have been tested with comparative studies and randomized controlled trials,whereas the other more recent ones still require a deeper evaluation.The purpose of the latter is to verify whether reflux is abolished or significantly reduced after intervention,whether there is a valid high pressure zone at the gastroesophageal junction,and whether esophagitis,when present,has disappeared.Unfortunately in a certain number of cases,and especially in the more recently introduced ones,the evaluation has been based almost exclusively on subjective criteria,such as improvement in the quality of life,remission of heartburn and regurgitation,and reduction or suspension of antacid and antisecretory drug consumption.However,with the most studied techniques such as TIF and STRETTA,an improvement in symptoms better than that of laparoscopic fundoplication can often be observed,whereas the number of acid episodes and acid exposure time are similar or higher,as if the acid refluxes are better tolerated by these patients.The suspicion of a local hyposensitivity taking place after antireflux endoscopic intervention seems confirmed by a Bernstein test at least for STRETTA.This examination should be done for all the other techniques,both old and new,to identify the ones that reassure rather than cure.In conclusion,the evaluation of the effectiveness of the endoscopic anti-reflux techniques should not be based exclusively on subjective criteria,but should also be confirmed by objective examinations,because there might be a gap between the improvement in symptoms declared by the patient and the underlying pathophysiologic alterations of GERD.展开更多
BACKGROUND Self-expanding metal stents are the main palliative treatment modality for unresectable esophageal cancer. Gastroesophageal reflux is a common adverse outcome after placement of esophageal stent for cancer ...BACKGROUND Self-expanding metal stents are the main palliative treatment modality for unresectable esophageal cancer. Gastroesophageal reflux is a common adverse outcome after placement of esophageal stent for cancer involving the gastroesophageal junction and the gastric cardia. Anti-reflux stents with valve have been designed to prevent the acid reflux. The superiority of anti-reflux stent over standard stent in preventing gastroesophageal reflux has not been established well. This study compares the anti-reflux stent and the standard stent in terms of their efficacy to prevent acid reflux.AIM To compare the standard and the anti-reflux stents in terms of their efficacy,safety, and complications.METHODS The meta-analysis included 8 randomized clinical trials(RCTs) to compare pooled outcomes of total 395 patients. Primary outcomes include improvement in reflux symptoms and dysphagia score. Secondary outcomes include complications of stent migration, occlusion, and bleeding.RESULTS A total of eight RCTs were included in the meta-analysis. Compared to the standard stent, the anti-reflux stent showed a trend towards reduction in the dysphagia score without reaching a statistical significance [Standardized mean difference(SMD):-0.33(-0.71, 0.05); P = 0.09, I2: 37%]. There was no statistical difference in the gastrointestinal reflux(GER) scores between the two types of stents [SMD:-0.17(-0.78, 0.45); P = 0.008, I2: 74%]. Compared to standard stent,anti-reflux stent showed no difference in the risk of stent migration [OR: 1.37(0.66, 2.83); P = 0.40, I2: 0 %], bleeding [OR: 1.43(0.40, 5.13); P = 0.59, I2: 0 %], and obstruction [OR: 1.66(0.60, 4.60); P = 0.33, I2: 0 %].CONCLUSION Traditional self-expanding standard esophageal stent and anti-reflux stent with valve are similar in terms of outcomes and complications.展开更多
Gastroesophageal reflux disease (GERD) is one of the most commonlyencountered digestive diseases in the world, with the prevalence continuing toincrease. Many patients are successfully treated with lifestyle modificat...Gastroesophageal reflux disease (GERD) is one of the most commonlyencountered digestive diseases in the world, with the prevalence continuing toincrease. Many patients are successfully treated with lifestyle modifications andproton pump inhibitor therapy, but a subset of patients require more aggressiveintervention for control of their symptoms. Surgical treatment with fundoplicationis a viable option for patients with GERD, as it attempts to improve the integrityof the lower esophageal sphincter (LES). While surgery can be as effective asmedical treatment, it can also be associated with side effects such as dysphagia,bloating, and abdominal pain. Therefore, a thorough pre-operative assessment iscrucial to select appropriate surgical candidates. Newer technologies arebecoming increasingly available to help clinicians identify patients with true LESdysfunction, such as pH-impedance studies and high-resolution manometry(HRM). Pre-operative evaluation should be aimed at confirming the diagnosis ofGERD, ruling out any major motility disorders, and selecting appropriate surgicalcandidates. HRM and pH testing are key tests to consider for patients with GERDlike symptoms, and the addition of provocative measures such as straight legraises and multiple rapid swallows to HRM protocol can assess the presence ofunderlying hiatal hernias and to test a patient’s peristaltic reserve prior tosurgery.展开更多
BACKGROUND There is little data available on the role of new anti-reflux plastic stents(ARPSs).AIM To compare the use of ARPSs with that of traditional plastic stents(TPSs)for patients with biliary strictures.METHODS ...BACKGROUND There is little data available on the role of new anti-reflux plastic stents(ARPSs).AIM To compare the use of ARPSs with that of traditional plastic stents(TPSs)for patients with biliary strictures.METHODS Consecutive patients with biliary strictures who underwent first endoscopic biliary stenting between February 2016 and May 2019 were included.The onset of stent-related cholangitis,stent patency,clinical success,and other adverse events were evaluated.RESULTS Sixty-seven patients in the ARPS group and 66 patients in the TPS group were included in the final analyses.Fewer patients experienced stent-related cholangitis in the ARPS group than that in the TPS group(8 patients vs 18 patients;P=0.030).The median time till the onset of first stent-related cholangitis was later in the ARPS group than that in the TPS group(128.5 d vs 76 d;P=0.039).The cumulative median stent patency in the ARPS group was 185 d,which was significantly longer than that in the TPS group(133 d;P=0.001).The clinical success rates and other adverse events did not significantly differ between both groups.CONCLUSION Placement of new ARPS might be a safe and effective optional therapeutic strategy to reduce the risk of stent-related cholangitis and prolong stent patency.展开更多
The Upper Shihezi sedimentary rocks in the Linxing region has been estimated with a significant volume of tight sandstone gas.However,lateral distribution of the present-day stress magnitude is poorly understood,which...The Upper Shihezi sedimentary rocks in the Linxing region has been estimated with a significant volume of tight sandstone gas.However,lateral distribution of the present-day stress magnitude is poorly understood,which limits further gas production.Hence,a one-dimensional mechanical earth model and a three-dimensional heterogeneous geomechanical model are built to address this issue.The results indicate that the strike-slip stress regime is dominant in the Upper Shihezi Formation.Relatively low stresses are mainly located around wells L-60,L-22,L-40,L-90,etc,and stress distributions exhibit the similarity in the Members H2 and H4.The differential stresses are relatively low in the Upper Shihezi Formation,suggesting that complex hydraulic fracture networks may be produced.Natural fractures in the Upper Shihezi Formation contribute little to the overall gas production in the Linxing region.In addition,the minimum principal stress gradient increases with Young's modulus,suggesting that the stiffer rocks commonly convey higher stress magnitudes.There is a strong interplay between stress distribution and heterogeneity in rock mechanics.Overall,the relative error between the predicted and measured results is less than 10%,implying that the predicted stress distribution is reliable and can be used for subsequent analysis in the Linxing region.展开更多
基金financially supported by the National Science and Technology Major Project of China (grant No. 2016ZX05066001–002)the National Science Foundation for Young Scientists of China (grant No. 41702171)the Program for Excellent Talents in Beijing (grant No. 2017000020124G107)
文摘Determining the process of densification and tectonic evolution of tight sandstone can help to understand the distribution of reservoirs and find relatively high-permeability areas.Based on integrated approaches of thin section,scanning electron microscopy(SEM),cathode luminescence(CL),nuclear magnetic resonance(NMR),X-ray diffraction(XRD),N2 porosity and permeability,micro-resistivity imaging log(MIL)and three-dimensional seismic data analysis,this work discussed the reservoir characteristics of the member 8 of the Permian Xiashihezi Formation(He 8 sandstones)in the Linxing area of eastern Ordos Basin,determined the factors affecting reservoir quality,and revealed the formation mechanism of relatively high-permeability areas.The results show that the He 8 sandstones in the Linxing area are mainly composed of feldspathic litharenites,and are typical tight sandstones(with porosity<10%and permeability<1 mD accounting for 80.3%of the total samples).Rapid burial is the main reason for reservoir densification,which resulted in 61%loss of the primary porosity.In this process,quartz protected the original porosity by resisting compaction.The cementation(including carbonate,clay mineral and siliceous cementation)further densified the sandstone reservoirs,reducing the primary porosity with an average value of 28%.The calcite formed in the eodiagenesis occupied intergranular pores and affected the formation of the secondary pores by preventing the later fluid intrusion,and the Fe-calcite formed in the mesodiagenetic stage densified the sandstones further by filling the residual intergranular pores.The clay minerals show negative effects on reservoir quality,however,the chlorite coatings protected the original porosity by preventing the overgrowth of quartz.The dissolution of feldspars provides extensive intergranular pores which constitute the main pore type,and improves the reservoir quality.The tectonic movements play an important role in improving the reservoir quality.The current tectonic traces of the study area are mainly controlled by the Himalayan movement,and the high-permeability reservoirs are mainly distributed in the anticline areas.Additionally,the improvement degree(by tectonic movements)of reservoir quality is partly controlled by the original composition of the sandstones.Thus,the selection of potential tight gas well locations in the study area should be focused on the anticline areas with relatively good original reservoir quality.And the phenomena can be referenced for other fluvial tight sandstone basins worldwide.
文摘Gastroesophageal reflux disease has an increasing incidence and prevalence worldwide.A significant proportion of patients have a suboptimal response to proton pump inhibitors or are unwilling to take lifelong medication due to concerns about long-term adverse effects.Endoscopic anti-reflux therapies offer a minimally invasive option for patients unwilling to undergo surgical treatment or take lifelong medication.The best candidates are those with a good response to proton pump inhibitors and without a significant sliding hiatal hernia.Transoral incisionless fundoplication and nonablative radiofrequency are the techniques with the largest body of evidence and that have been tested in several randomized clinical trials.Band-assisted ligation techniques,anti-reflux mucosectomy,antireflux mucosal ablation,and new plication devices have yielded promising results in recent noncontrolled studies.Nonetheless,the role of endoscopic procedures remains controversial due to limited long-term and comparative data,and no consensus exists in current clinical guidelines.This review provides an updated summary focused on the patient selection,technical details,clinical success,and safety of current and future endoscopic anti-reflux techniques.
文摘AIM: With the availability of a minimally invasive approach, anti-reflux surgery has recently experienced a renaissance as a cost-effective alternative to life-long medical treatment in patients with gastroesophageal reflux disease (GERD). We are not aware of the fact whether reflux episodes causing complaints for a long time i.e., at least for one year are associated with metabolic changes in the lower esophageal sphincter, and if so, whether these may influence functional results achieved after anti-reflux surgery. METHODS: Between 1 January 2001 and 31 December 2002 we performed anti-reflux surgery on 79 patients. Muscle samples were taken from the lower esophageal sphincter (LES) in 33 patients during anti-reflux surgery. Inclusion criteria were: LES resting pressure below 10 mmHg and a marked, pH proven acid exposure to the esophagus of at least one year's duration, causing subjective complaints and requiring continuous proton pump inhibitor treatment. Control samples were obtained from muscle tissue in the gastroesophageal junction that had been removed from 17 patients undergoing gastric or esophageal resection. Metabolic and lysosomal enzyme activities and special protein concentrations 16 parameters in total were evaluated in tissue taken from control specimens and tissue taken from patients with GERD. The biochemical parameters of these intra-operative biopsies were used to correlate the results of anti-reflux operations (Visick Ⅰ and Ⅱ-Ⅲ). RESULTS: In the reflux-type muscle, we found a significant increase of the energy-enzyme activities e.g., creatine kinase, lactate dehydrogenase, β-hydroxybutyrate dehydrogenase, and aspartate aminotransaminase-. The concentration of the structural protein S-100 and the myofibrillar protein troponin Ⅰ were also significantly increased. Among lysosomal enzymes, we found that the activities of cathepsin B, tripeptidyl-peptidase Ⅰ, dipeptidyl-peptidase Ⅱ, β-hexosaminidase B, β-mannosidase and β-galactosidase were significantly decreased as compared to the control LES muscles. By analyzing the activity values of the 9 patients in Visick groups Ⅱ and Ⅲ at two months post-surgery, we found a significant increase in the activity of the so-called energy-enzyme values and in the concentration of structural and myofibrillar proteins as compared to the rest of the reflux patients. CONCLUSION: Our results call attention to the metabolic changes that occurred in the LES muscles of reflux patients. The developing hypertrophy-like changes of LES muscles may be a reason for complaints after anti-reflux surgery, which consisted mainly of reports of persisting dysphagia.
文摘Endoscopic anti-reflux treatment is emerging as a new option for gastroesophageal reflux disease(GERD)treatment in patients with the same indications as for laparoscopic fundoplication.There are many techniques,the first of which are transoral incisionless fundoplication(TIF)and nonablative radio-frequency(STRETTA)that have been tested with comparative studies and randomized controlled trials,whereas the other more recent ones still require a deeper evaluation.The purpose of the latter is to verify whether reflux is abolished or significantly reduced after intervention,whether there is a valid high pressure zone at the gastroesophageal junction,and whether esophagitis,when present,has disappeared.Unfortunately in a certain number of cases,and especially in the more recently introduced ones,the evaluation has been based almost exclusively on subjective criteria,such as improvement in the quality of life,remission of heartburn and regurgitation,and reduction or suspension of antacid and antisecretory drug consumption.However,with the most studied techniques such as TIF and STRETTA,an improvement in symptoms better than that of laparoscopic fundoplication can often be observed,whereas the number of acid episodes and acid exposure time are similar or higher,as if the acid refluxes are better tolerated by these patients.The suspicion of a local hyposensitivity taking place after antireflux endoscopic intervention seems confirmed by a Bernstein test at least for STRETTA.This examination should be done for all the other techniques,both old and new,to identify the ones that reassure rather than cure.In conclusion,the evaluation of the effectiveness of the endoscopic anti-reflux techniques should not be based exclusively on subjective criteria,but should also be confirmed by objective examinations,because there might be a gap between the improvement in symptoms declared by the patient and the underlying pathophysiologic alterations of GERD.
文摘BACKGROUND Self-expanding metal stents are the main palliative treatment modality for unresectable esophageal cancer. Gastroesophageal reflux is a common adverse outcome after placement of esophageal stent for cancer involving the gastroesophageal junction and the gastric cardia. Anti-reflux stents with valve have been designed to prevent the acid reflux. The superiority of anti-reflux stent over standard stent in preventing gastroesophageal reflux has not been established well. This study compares the anti-reflux stent and the standard stent in terms of their efficacy to prevent acid reflux.AIM To compare the standard and the anti-reflux stents in terms of their efficacy,safety, and complications.METHODS The meta-analysis included 8 randomized clinical trials(RCTs) to compare pooled outcomes of total 395 patients. Primary outcomes include improvement in reflux symptoms and dysphagia score. Secondary outcomes include complications of stent migration, occlusion, and bleeding.RESULTS A total of eight RCTs were included in the meta-analysis. Compared to the standard stent, the anti-reflux stent showed a trend towards reduction in the dysphagia score without reaching a statistical significance [Standardized mean difference(SMD):-0.33(-0.71, 0.05); P = 0.09, I2: 37%]. There was no statistical difference in the gastrointestinal reflux(GER) scores between the two types of stents [SMD:-0.17(-0.78, 0.45); P = 0.008, I2: 74%]. Compared to standard stent,anti-reflux stent showed no difference in the risk of stent migration [OR: 1.37(0.66, 2.83); P = 0.40, I2: 0 %], bleeding [OR: 1.43(0.40, 5.13); P = 0.59, I2: 0 %], and obstruction [OR: 1.66(0.60, 4.60); P = 0.33, I2: 0 %].CONCLUSION Traditional self-expanding standard esophageal stent and anti-reflux stent with valve are similar in terms of outcomes and complications.
文摘Gastroesophageal reflux disease (GERD) is one of the most commonlyencountered digestive diseases in the world, with the prevalence continuing toincrease. Many patients are successfully treated with lifestyle modifications andproton pump inhibitor therapy, but a subset of patients require more aggressiveintervention for control of their symptoms. Surgical treatment with fundoplicationis a viable option for patients with GERD, as it attempts to improve the integrityof the lower esophageal sphincter (LES). While surgery can be as effective asmedical treatment, it can also be associated with side effects such as dysphagia,bloating, and abdominal pain. Therefore, a thorough pre-operative assessment iscrucial to select appropriate surgical candidates. Newer technologies arebecoming increasingly available to help clinicians identify patients with true LESdysfunction, such as pH-impedance studies and high-resolution manometry(HRM). Pre-operative evaluation should be aimed at confirming the diagnosis ofGERD, ruling out any major motility disorders, and selecting appropriate surgicalcandidates. HRM and pH testing are key tests to consider for patients with GERDlike symptoms, and the addition of provocative measures such as straight legraises and multiple rapid swallows to HRM protocol can assess the presence ofunderlying hiatal hernias and to test a patient’s peristaltic reserve prior tosurgery.
文摘BACKGROUND There is little data available on the role of new anti-reflux plastic stents(ARPSs).AIM To compare the use of ARPSs with that of traditional plastic stents(TPSs)for patients with biliary strictures.METHODS Consecutive patients with biliary strictures who underwent first endoscopic biliary stenting between February 2016 and May 2019 were included.The onset of stent-related cholangitis,stent patency,clinical success,and other adverse events were evaluated.RESULTS Sixty-seven patients in the ARPS group and 66 patients in the TPS group were included in the final analyses.Fewer patients experienced stent-related cholangitis in the ARPS group than that in the TPS group(8 patients vs 18 patients;P=0.030).The median time till the onset of first stent-related cholangitis was later in the ARPS group than that in the TPS group(128.5 d vs 76 d;P=0.039).The cumulative median stent patency in the ARPS group was 185 d,which was significantly longer than that in the TPS group(133 d;P=0.001).The clinical success rates and other adverse events did not significantly differ between both groups.CONCLUSION Placement of new ARPS might be a safe and effective optional therapeutic strategy to reduce the risk of stent-related cholangitis and prolong stent patency.
基金The authors would like to thank the financial support from the National Natural Science Foundation of China(41702130,41872171 and 41672146)National Science and Technology Major Project(2016ZX05066)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘The Upper Shihezi sedimentary rocks in the Linxing region has been estimated with a significant volume of tight sandstone gas.However,lateral distribution of the present-day stress magnitude is poorly understood,which limits further gas production.Hence,a one-dimensional mechanical earth model and a three-dimensional heterogeneous geomechanical model are built to address this issue.The results indicate that the strike-slip stress regime is dominant in the Upper Shihezi Formation.Relatively low stresses are mainly located around wells L-60,L-22,L-40,L-90,etc,and stress distributions exhibit the similarity in the Members H2 and H4.The differential stresses are relatively low in the Upper Shihezi Formation,suggesting that complex hydraulic fracture networks may be produced.Natural fractures in the Upper Shihezi Formation contribute little to the overall gas production in the Linxing region.In addition,the minimum principal stress gradient increases with Young's modulus,suggesting that the stiffer rocks commonly convey higher stress magnitudes.There is a strong interplay between stress distribution and heterogeneity in rock mechanics.Overall,the relative error between the predicted and measured results is less than 10%,implying that the predicted stress distribution is reliable and can be used for subsequent analysis in the Linxing region.