Quantitative Evaluation Of Oil-gas Transporting Ability By Major Pathways Of Oil-source Faults Of Daliuquan Area In Jizhong Depression

In order to study the distribution law of oil-gas in Daliuquan area of Jizhong Depression and guide the exploration of oil-gas reservoirs in lower-source-upper-reservoir petroleum bearing basin,based on the study of regional geological characteristics in Daliuquan area of Jizhong Depression,the faults in the study area were analyzed by combining the three-dimensional high resolution seismic fine interpretation data,logging data and other data.According to the characteristics of fault development and distribution and fault activity,the fault system in the study area was divided.The oil-source faults were determined by combining the source-reservoir-caprock assemblages and the main hydrocarbon accumulation periods in the study area.According to the relative strength of fault activity,the active period and the after active period were divided.Through studying the oil-gas transporting mechanism and pathway characteristics of oil-source faults in different periods,the oil-gas transporting major pathways of oil-source faults in different periods and their ability influencing factors were determined.The oil-gas transporting major pathways of oil-source faults in different periods in Daliuquan area of Jizhong Depression were identified separately,and then the ability influencing factors were summarized,quantitative evaluation of oil-gas transporting ability of major pathways of oil-source faults in different periods was carried out respectively.Combining with the oil-gas distribution law in Daliuquan area of Jizhong Depression,the control effect of oil-gas transporting major pathways distribution and their ability of oil-source faults on oil-gas accumulation was analyzed and summarized.The results show that:?1?during the active period,the oil-gas transporting pathway of oil-source faults is associated fracture,and the oil-gas transporting major pathway is the section where the fault activity rate is greater than the minimum activity rate required for the successive distribution of associated fracture.The main factors affecting the oil-gas transporting ability are the fault activity rate,the width of major pathway,the fault distance,dip angle and the shale content of the formations on both sides of the fault;after the active period,the oil-gas transporting pathway of oil-source faults is the pore of fault filler,and the oil-gas transporting major pathway is the converging ridge of fluid potential on fault plane.The main factors affecting the oil-gas transporting ability are the width and amplitude of major pathway,dip angle and shale content of fault filler.?2?There are altogether 12oil-source faults in Daliuquan area of Jizhong Depression,including 17 oil-gas transporting major pathways of oil-source faults in active period and 39 oil-gas transporting major pathways of oil-source faults after active period.?3?Based on the analysis of development characteristics,dynamic characteristics and associated fracture developmental degree,the quantitative evaluation formulas of oil-gas transporting ability of major pathway in oil-source faults in active period are established by selecting five main influencing factors.Based on the analysis of development characteristics,dynamic characteristics and resistance characteristics,the quantitative evaluation formulas of oil-gas transporting ability of major pathway in oil-source faults after active period are established by selecting four main influencing factors.?4?There are three variation laws of oil-gas transporting ability of major pathways in oil-source faults in active period in Daliuquan area of Jizhong Depression,while there are eight variation laws of oil-gas transporting ability of major pathways in oil-source faults after active period.In active period,F₈?2?major pathway has the strongest oil-gas transporting ability,and F₁₁?3?major pathway has the strongest oil-gas transporting ability after active period.In active period,the oil-gas transporting ability of major pathways is generally stronger in the Es₃^?and Es₃^?,and relatively stronger in the Es₃^?,Es₂ and Ng after active period.In the Es₃^?,the oil-gas transporting ability of the major pathways in the central part of the study area is stronger in different periods,while the oil-gas transporting ability of the major pathways on both sides of the study area is weaker in different periods.?5?Distribution and ability of oil-gas transporting major pathways of oil-source faults in different periods in Daliuquan area of Jizhong Depression not only control oil-gas accumulation location,but also control oil-gas accumulation layers.Distribution and ability of oil-gas transporting major pathways of oil-source faults in active period contribute more to oil-gas accumulation than that after active period.