Gas And Water Distribution Characteristics And Accumulation Process Of Dongpo Shaximiao Formation In The Western Sichuan Depression

Foreland basin,also known as the Longmen Shan foreland basin?now call it the Western Sichuan Depression?,which belongs to the Sichuan Basin Midwest.The Eastern Slope of West Sichuan Depression belong to a secondary structure in western Sichuan Depression,including Hexingchang-gaomiaozi,fenggu,yongtai,zhongjiang-Huilong and that the new field-Shiquan field a total of five three-dimensional seismic exploration area block,involves three tectonic zone,as a whole showed " aron clip a recess" feature.Oil and gas exploration of eastern slope area in western Sichuan Depression began in the 1990 s,1995 Sichuan Petroleum Administration?CNPC?in ZJ area of the first exploration well drilled CQ181 wells in Sichuan spring shaximiao drilling encountered oil and gas shows good layer 2013 as well GM 32 natural gas production in the sand JS₃?3-2? group test 6.8523 × 104m³ / d,unimpeded flow of 7.5287 × 104m³ / d industrial gas flow,and discovered gaomiaozi gas reservoir.However,due to western Sichuan depression after more than tectonic movements,resulting in complex geological conditions the region,widespread overpressure gas reservoirs,gas and water complex relationships accumulation process not yet have a unified law clear understanding,in order to further clarify the next exploration and development goals,sand off the study area matching conditions,research gas and water distribution and accumulation process also essential.This study systematically collect the various seismic horizons of eastern slope in western Sichuan Depression,including logging,logging and gas test data,analysis of tests on the sedimentology,structural geology,reservoir geology,hydrocarbon system and method for forming dynamics principle and petroleum geology to carry out typical gas reservoir anatomy and to explore gas and water distribution,combined with fluid inclusions determine accumulation time,analyzed accumulation area process,provide the basis for hydrocarbon accumulation rule.Studies have shown that gas reservoirs are mainly distributed in gaomiaozi and zhongjiang region.Oil and gas shows the best in gaomiaozi shasan layer and in zhongjiang area shayi and shaer are the best.Shaximiao gas and water distribution is mainly affected by the fault,the impact of local structures and sand body.Natural gas,mainly in the plane and in zhongjiang and gaomiaozi local high enrichment and lower Shaximiao controlled by lithology strong sand group inzhongjiang area,The phenomenon that gas exist high part and water exist low part.Close to the fault at fault because the relief effect of gas containing low abundance,easy to produce water,north-south tectonic fault zone is located to the gas holder is not good,a few mouthfuls of exploration wells currently mainly produced water,well away from the hydrocarbon abundance Valley source fault and cause gas tight storage is bad.Longitudinal JS₁¹ JS₁⁴ JS₂³ JS₃^3-2 JS₃?3-3? etc.horizon display is better,the current situation of the development of the study area did not show a uniform air-water interface,only the presence of gas gaomiaozi area JS₃^3-2 water more thoroughly different dessert area,air-water interface is about-2420 m,no obvious other layers of air-water interface.Combined fluid inclusion data,through the typical gas reservoirs were dissected,analyzed accumulation process I think eastern slope region experienced three episodic 135-125 Ma,100-88 Ma,85-68 Ma etc.Yanshan period expulsion process.In the oil and gas accumulation period migrated into the reservoir through shaximiao hydrocarbon source fault speed channel after the gas into the sand,according to the direction of fluid potential to reduce migration and accumulation in the local structural high,but the long-distance migration process due to lack of motivation,leading to distant source of sand filled with low gas.Himalayan tectonic uplift and erosion caused by the formation of natural gas under high pressure anomaly readjusted while squeezing and lifting so that the fault re-open,the pressure relief channel is formed,gas migration to the roots of relief,and the water is staying at fault nearby,natural gas migrated upward along the fault continues,it is easily understood with low gas abundance produced water nearby faults.Through the typical gas reservoirs were dissected,analyzed and integrated into the accumulation process,infer West Sichuan Depression Dongpo area Shaximiao gas reservoir sand off factors affected match,tectonic evolution and sedimentary evolution,etc.,with "the controlling structure,Fault and sand body control movement,Reservoirs control accumulation,evolution control tune " accumulation evolution model.