Study On The Formation And Exploration Of Subtle Reservoir In Fault Basin Of Continental Facies

By the guide of the theories such as petroleum geology, sequencestratigraphy, sedimentology, pool-forming dynamics; with the tackles and technologiessoftwares of the power function computer workstation, GeoFram,LandMarkgeoscience,Jason reservoir inversion,Stratmagic waveform sort,Geoprobe3D visual, based on the geology, seism, logging well, analyzed and tested data in the Raoyang oilenrichment sag in Bohai Gulf, sum up the forming condition and main type of subtlereservoir in the continental rift-subsidence basin. The forming mechanism anddevelopment mode of subtle reservoir, as well as the paragenesis and complementarityfeatures of forming and distribution between subtle and structural reservoirs arediscussed in respect of structure, sediment, reservoir, diagenesis, and hydrocarbonresources etc.For the first time, researched forming conditions and types of favored subtle poolsin system in the Raorang sag. As the hydrocarbon reservoirs about the sandstone updippinch out,sandstone side dip pinch out,sandstone lens lithology, sandstone stratumoverlap, sandstone stratum denudation, along trend sidehill, inverse trend hillsideburied hill dope, biology limestone(carbonate rock), oil shale split types, blocked out bythe lithology compact band, are the main types of the subtle reservoirs. Put forward thatthe buried hill palaeotopography, bluff negative landform, lake coastline whirligig belts, depositional slope-break zone, lobate sandstone areas in the deltaic front are the maincontrolling and developing areas forming the subtle pools. And thought the oil and gassource condition was more important controlling factor for forming subtle pool than tectonic pool. The conditions matching is the furthest the forming of the subtle poolssuch as the distributing area of efficiency source rock, richness oil depression, themajor source rocks, self-generating and self-preserving. Put forward inaugurated thatthe distribution and formation took out paragenesis and complementarity betweentectonic pool and subtle one. Paragenesis represents the both things lays in the samesection and area; complementarity behave opposition. Subtle reservoir in thecontinental rift-subsidence basin, have very complicated forming mechanism, and isdifficult to discover, prove and evaluate, and also has high exploration drilling risk.This paper summarizes the train of thoughts, exploration procedure, technical method, experiences and enlightenment during the exploration of subtle reservoir in fault basinof continental facies, based on the analysis of exploration case of typical subtlereservoir with various types.