Micro-fractures are developed in volcanic layers of Cretaceous Yingcheng Fm in the deep part of Xujiaweizi fault depression,Songliao Basin.In the process of well drilling,various complex problems happen,such as boreho...Micro-fractures are developed in volcanic layers of Cretaceous Yingcheng Fm in the deep part of Xujiaweizi fault depression,Songliao Basin.In the process of well drilling,various complex problems happen,such as borehole wall slabbing and collapse and serious fluid leakage.Based on conventional drilling fluid plugging evaluation methods,the real situations cannot be presented accurately,especially in fracture feature simulation and plugging effect evaluation.Therefore,a specific micro-fracture plugging evaluation method was put forward especially for high-temperature deep wells in the paper.It is a new type of micro-fracture core model with the fracture apertures in the range of 1-50 mm.It is made of aluminosilicate that is compositionally close to natural rocks.It is good in repeatability with fracture-surface roughness,pore development and fracture-surface morphology close to natural fractures.Obviously,this new model makes up for the deficiencies of the conventional methods.A new micro-fracture plugging evaluation instrument was independently designed with operating temperature of 200℃ and operating pressure of 3.5-5.0 MPa.It can be used to simulate the flow regime of downhole operating fluids,with the advantages of low drilling fluid consumption,convenient operation and low cost.The plugging capacity of the organo-silicone drilling fluid system was evaluated by using this instrument.It is shown that the grain size distribution of the drilling fluid is improved and its anti-collapse capacity is enhanced.Based on the field test in Well XSP-3,the safe drilling problems in volcanic layers with developed micro-fractures are effectively solved by using the drilling fluid formula which is optimized by means of this evaluation method.And the safe drilling is guaranteed in the deep fractured formations in this area.展开更多
Exploration and development of volcanic gas reservoirs is a world-class problem,and less experience can be learned at home and abroad.Through study of reservoir-forming conditions of Xushen gas field,four sets of hydr...Exploration and development of volcanic gas reservoirs is a world-class problem,and less experience can be learned at home and abroad.Through study of reservoir-forming conditions of Xushen gas field,four sets of hydrocarbon source rocks,mainly mudstone and coal seam of Shahezi Formation,are identified in this gas field;its cap rocks are mudstone in Member 2 of Denglouku Formation,and Member 1 and Member 2 of Quantou Formation.By simulating reservoir-forming history,four filling periods of the Xushen gas field are determined,and the most favorable exploration targets are crater areas with structural highs,large thickness and good physical properties.On the basis of diagenetic mechanism study,the criteria of sequence series,lithology identification and reservoir types of gas reservoirs have been established;the volcanic rock bodies have been carefully depicted and the distribution laws of effective reservoirs of gas pools have been figured out.Based on evaluating reservoir-permeability characteristics of reservoirs,the gas well productivity characteristics(mainly type II,III and IV wells)have been identified,and the optimum design technology for volcanic gas reservoir development has been developed.The gas reservoirs in all blocks of Xushen gas field are classified into three types:singlebody gas reservoir model,disconnected multi-body gas reservoir model and interconnected multi-body gas reservoir model.Stimulation technologies,including multi-layer fracturing of vertical well,staged fracturing of open-hole horizontal well and volume fracturing,have been developed.According to gas well production performance,pressure change,well-controlled reserves and spatial distribution of volcanic bodies,combined with numerical simulation and prediction of gas reservoirs,the evaluation method of residual potential of volcanic gas reservoirs has been formed.Key technologies for effective exploration and development of complex volcanic gas reservoirs have been established and perfected,and bring good development effect.The research results can provide guidance and reference for exploration and development of similar gas reservoirs.展开更多
基金Project supported by CNPC Scientific Research and Technical Development Project“Research and Application of Supporting Drilling/Completion Techniques for Wells Treated with Special Technologies”(Grant No.2013T-0308-001).
文摘Micro-fractures are developed in volcanic layers of Cretaceous Yingcheng Fm in the deep part of Xujiaweizi fault depression,Songliao Basin.In the process of well drilling,various complex problems happen,such as borehole wall slabbing and collapse and serious fluid leakage.Based on conventional drilling fluid plugging evaluation methods,the real situations cannot be presented accurately,especially in fracture feature simulation and plugging effect evaluation.Therefore,a specific micro-fracture plugging evaluation method was put forward especially for high-temperature deep wells in the paper.It is a new type of micro-fracture core model with the fracture apertures in the range of 1-50 mm.It is made of aluminosilicate that is compositionally close to natural rocks.It is good in repeatability with fracture-surface roughness,pore development and fracture-surface morphology close to natural fractures.Obviously,this new model makes up for the deficiencies of the conventional methods.A new micro-fracture plugging evaluation instrument was independently designed with operating temperature of 200℃ and operating pressure of 3.5-5.0 MPa.It can be used to simulate the flow regime of downhole operating fluids,with the advantages of low drilling fluid consumption,convenient operation and low cost.The plugging capacity of the organo-silicone drilling fluid system was evaluated by using this instrument.It is shown that the grain size distribution of the drilling fluid is improved and its anti-collapse capacity is enhanced.Based on the field test in Well XSP-3,the safe drilling problems in volcanic layers with developed micro-fractures are effectively solved by using the drilling fluid formula which is optimized by means of this evaluation method.And the safe drilling is guaranteed in the deep fractured formations in this area.
基金The work was supported by the Major Project of PetroChina Company Limited(No.110017333011).
文摘Exploration and development of volcanic gas reservoirs is a world-class problem,and less experience can be learned at home and abroad.Through study of reservoir-forming conditions of Xushen gas field,four sets of hydrocarbon source rocks,mainly mudstone and coal seam of Shahezi Formation,are identified in this gas field;its cap rocks are mudstone in Member 2 of Denglouku Formation,and Member 1 and Member 2 of Quantou Formation.By simulating reservoir-forming history,four filling periods of the Xushen gas field are determined,and the most favorable exploration targets are crater areas with structural highs,large thickness and good physical properties.On the basis of diagenetic mechanism study,the criteria of sequence series,lithology identification and reservoir types of gas reservoirs have been established;the volcanic rock bodies have been carefully depicted and the distribution laws of effective reservoirs of gas pools have been figured out.Based on evaluating reservoir-permeability characteristics of reservoirs,the gas well productivity characteristics(mainly type II,III and IV wells)have been identified,and the optimum design technology for volcanic gas reservoir development has been developed.The gas reservoirs in all blocks of Xushen gas field are classified into three types:singlebody gas reservoir model,disconnected multi-body gas reservoir model and interconnected multi-body gas reservoir model.Stimulation technologies,including multi-layer fracturing of vertical well,staged fracturing of open-hole horizontal well and volume fracturing,have been developed.According to gas well production performance,pressure change,well-controlled reserves and spatial distribution of volcanic bodies,combined with numerical simulation and prediction of gas reservoirs,the evaluation method of residual potential of volcanic gas reservoirs has been formed.Key technologies for effective exploration and development of complex volcanic gas reservoirs have been established and perfected,and bring good development effect.The research results can provide guidance and reference for exploration and development of similar gas reservoirs.
