In mature reservoirs,the success of preformed particle gel（PPG） treatment rests primarily on the ability of the PPG to reduce and/or plug the high permeable formations,but not damage the low permeable formations.Sta...In mature reservoirs,the success of preformed particle gel（PPG） treatment rests primarily on the ability of the PPG to reduce and/or plug the high permeable formations,but not damage the low permeable formations.Static test models（filtration test model and pressure test model）were used to determine the effect of PPG on low permeable formations.This work used a strong preformed particle gel,Daqing（DQ） gel made by a Chinese company.The particle gel sizes were ranged from 30 to 120 mesh for this work.PPGs are sized in a millimeter or micrometer,which can absorb over a hundred times their weight in liquids.The gel strength was approximately 6500 Pa for a completely swollen PPG with 1 %（weight percentage） NaCl solution（brine）.0.05 %,1 %,and 10 % NaCl solutions were used in experiments.Sandstone core permeability was measured before and after PPG treatments.The relationship between cumulative filtration volumes versus filtration times was determined.The results indicate that DQ gels of a particle size of 30–80 mesh did not damage the cores of a low permeability of 3–25 m D.The DQ gels of a smaller particle size ranging from 100 to 120 mesh damaged the core and a cake was formed on the core surface.The results also indicate that more damage occurred when a high load pressure（400 psi） was applied on the high permeability cores（290–310 m D）.The penetration of the particle gelsinto the low permeable formations can be decreased by the best selection of gel types,particle sizes,and brine concentrations.展开更多
By using the integrated methods includingsandbodies modelling of the outcrops, sedimentary facies ofthe cores and well logs of the drilled wells, and the reservoircorrelation of interwells, it is thought that the sand...By using the integrated methods includingsandbodies modelling of the outcrops, sedimentary facies ofthe cores and well logs of the drilled wells, and the reservoircorrelation of interwells, it is thought that the sandstone res-ervoirs of Kela-2 gas field are a suit of high-quality naturalgas reservoirs with great thickness, extensive and continuousdistribution, high porosity and permeability, and a few bar-rier beds. Sedimentary facies and microfacies are the mainfactors controlling the reservoir distribution and interiorheterogeneity. Based on a great deal of data of rock’s thinsections, porosity, permeability, and the parameters of capil-lary pressure, the reservoir diagenesis, controls, mechanismand evolution of pores have been studied. It is consideredthat compaction in the early stage and diagenetic dolomiteand calcite cements have effect on the decline of reservoirsproperty. Now compaction is chiefly middle to weak. Thebetter reservoirs have no or a few calcite cements. In theearly of deep buried stage, there are still mainly remainderprimary intergranular pores. The authigenic kaolinite ofreservoirs is the production of the dissolution of feldsparsand lithic fragments. The dissolution results in the partlymodified and broadened secondary intergranular pores. Inthe late of deep buried stage, structure fissures and over-pressure were in favor of improving and preservation ofthese pores.展开更多
The present work has been accomplished to carry out a detailed study of the characteristics of the Early Jurassic Datta Formation of Trans-Indus Ranges, Pakistan. The discovery of Saib well-1 (Gas and condensate disco...The present work has been accomplished to carry out a detailed study of the characteristics of the Early Jurassic Datta Formation of Trans-Indus Ranges, Pakistan. The discovery of Saib well-1 (Gas and condensate discovery from Jurassic limestone) in the study basin takes an active interest in carrying out extensive exploration activities in the same basin. Jurassic rocks especially Datta Sandstone and Samana Suk Limestone are acting as good reservoirs. The study unit consists of variegated sandstone interbedded with siltstone, carbonaceous clay, and shale and coal stringer. For the current work, two stratigraphic sections (Pezu and Abbo Wanda) have been measured. To examine its sedimentology, depositional environment, diagenetic settings, and reservoir characteristics, a detailed study was conducted and various laboratory techniques have been utilized. About 95 rock samples from the bottom to the top of both sections were collected, and 50 rock samples have been selected for thin section analysis and were examined under a polarizing microscope to show their mineralogical composition, diagenesis, and their reservoir characteristics. XRD (X-ray diffraction), Cathodoluminescence (CL), SEM (Scanning electron microscope) with EDS (Energy-dispersive spectroscope), and Core plug porosity and permeability analysis have been used to interpret its chemical and mineralogical composition and its reservoir characteristics, respectively. Based on field observations and thin section analysis, four depositional facies and six lithofacies have been established. The sedimentary structures, depositional facies, and lithofacies indicate that Datta Formation was deposited in a deltaic environment. Compactions, cementation, fracturing and dissolution can greatly affect the quality of reservoir rock. Based on thin section and SEM analysis, large numbers of primary pores, fracture and secondary pores were observed and connectivity between the pores is good, and at some places, these pores were filled through the authigenic clay minerals like kaolinite, mixed layers illite/smectite and chlorite that influences the reservoir characteristics. Primary pores (thin section) and secondary pores (dissolution pores) and core plug porosity and permeability data (porosity 13.23%-26.89% and permeability 0.12 to 149 mD) shows that Datta Formation has a good reservoir quality.展开更多
基金the Research Partnership to Secure Energy for America (RPSEA) for its financial support for this work
文摘In mature reservoirs,the success of preformed particle gel（PPG） treatment rests primarily on the ability of the PPG to reduce and/or plug the high permeable formations,but not damage the low permeable formations.Static test models（filtration test model and pressure test model）were used to determine the effect of PPG on low permeable formations.This work used a strong preformed particle gel,Daqing（DQ） gel made by a Chinese company.The particle gel sizes were ranged from 30 to 120 mesh for this work.PPGs are sized in a millimeter or micrometer,which can absorb over a hundred times their weight in liquids.The gel strength was approximately 6500 Pa for a completely swollen PPG with 1 %（weight percentage） NaCl solution（brine）.0.05 %,1 %,and 10 % NaCl solutions were used in experiments.Sandstone core permeability was measured before and after PPG treatments.The relationship between cumulative filtration volumes versus filtration times was determined.The results indicate that DQ gels of a particle size of 30–80 mesh did not damage the cores of a low permeability of 3–25 m D.The DQ gels of a smaller particle size ranging from 100 to 120 mesh damaged the core and a cake was formed on the core surface.The results also indicate that more damage occurred when a high load pressure（400 psi） was applied on the high permeability cores（290–310 m D）.The penetration of the particle gelsinto the low permeable formations can be decreased by the best selection of gel types,particle sizes,and brine concentrations.
文摘By using the integrated methods includingsandbodies modelling of the outcrops, sedimentary facies ofthe cores and well logs of the drilled wells, and the reservoircorrelation of interwells, it is thought that the sandstone res-ervoirs of Kela-2 gas field are a suit of high-quality naturalgas reservoirs with great thickness, extensive and continuousdistribution, high porosity and permeability, and a few bar-rier beds. Sedimentary facies and microfacies are the mainfactors controlling the reservoir distribution and interiorheterogeneity. Based on a great deal of data of rock’s thinsections, porosity, permeability, and the parameters of capil-lary pressure, the reservoir diagenesis, controls, mechanismand evolution of pores have been studied. It is consideredthat compaction in the early stage and diagenetic dolomiteand calcite cements have effect on the decline of reservoirsproperty. Now compaction is chiefly middle to weak. Thebetter reservoirs have no or a few calcite cements. In theearly of deep buried stage, there are still mainly remainderprimary intergranular pores. The authigenic kaolinite ofreservoirs is the production of the dissolution of feldsparsand lithic fragments. The dissolution results in the partlymodified and broadened secondary intergranular pores. Inthe late of deep buried stage, structure fissures and over-pressure were in favor of improving and preservation ofthese pores.
文摘The present work has been accomplished to carry out a detailed study of the characteristics of the Early Jurassic Datta Formation of Trans-Indus Ranges, Pakistan. The discovery of Saib well-1 (Gas and condensate discovery from Jurassic limestone) in the study basin takes an active interest in carrying out extensive exploration activities in the same basin. Jurassic rocks especially Datta Sandstone and Samana Suk Limestone are acting as good reservoirs. The study unit consists of variegated sandstone interbedded with siltstone, carbonaceous clay, and shale and coal stringer. For the current work, two stratigraphic sections (Pezu and Abbo Wanda) have been measured. To examine its sedimentology, depositional environment, diagenetic settings, and reservoir characteristics, a detailed study was conducted and various laboratory techniques have been utilized. About 95 rock samples from the bottom to the top of both sections were collected, and 50 rock samples have been selected for thin section analysis and were examined under a polarizing microscope to show their mineralogical composition, diagenesis, and their reservoir characteristics. XRD (X-ray diffraction), Cathodoluminescence (CL), SEM (Scanning electron microscope) with EDS (Energy-dispersive spectroscope), and Core plug porosity and permeability analysis have been used to interpret its chemical and mineralogical composition and its reservoir characteristics, respectively. Based on field observations and thin section analysis, four depositional facies and six lithofacies have been established. The sedimentary structures, depositional facies, and lithofacies indicate that Datta Formation was deposited in a deltaic environment. Compactions, cementation, fracturing and dissolution can greatly affect the quality of reservoir rock. Based on thin section and SEM analysis, large numbers of primary pores, fracture and secondary pores were observed and connectivity between the pores is good, and at some places, these pores were filled through the authigenic clay minerals like kaolinite, mixed layers illite/smectite and chlorite that influences the reservoir characteristics. Primary pores (thin section) and secondary pores (dissolution pores) and core plug porosity and permeability data (porosity 13.23%-26.89% and permeability 0.12 to 149 mD) shows that Datta Formation has a good reservoir quality.
