Study On Characteristics Of Middle-shallow Reservoir In Yinggehai Basin

Yinggehai Basin is a typical high-temperature and overpressured basin of China’soffshore sea area. Years of exploration has been confirmed that Yinggehai basin hasabundant natural gas resources. At present, normal temperature and pressureenvironment of shallow oil and gas exploration technology is relatively mature, andthe exploration potential is relatively clear. But the middle-deep reservoir ofhigh-temperature and high-pressure, has low degree of exploration. Explorationpotential should be further studied.This paper summarizes the geological background of the region, the evolutioncharacteristics of the distribution in the shallow sedimentary facies (Littoral, Neriticand Bathyal).Studied the formation mechanism of the modern high-temperature andoverpressurization, discusses several distribution patterns of the overpressurization.And comfirm that the main reason for the present overpressured formation was theuncompaction which caused by the rapid deposition, followed by supercharging fromhydrocarbon of the deep source rocks; pressure transmission take the role of the diapirzone significantly alter the distribution pattern of the overpressurization, to cause thepressure from deep formation relief to the shallow formation.First of all, Study the petrological characteristics,diagenesis, pore structure andreservoir properties of the shallow reservoir rocks in Yinggehai Basin on the basis ofhaving observed the core observation and experimental analysis. The conclusion isthat the best reservoir properties is the diapir zone.In the diapir reservoir properties inLedong zone is better than Dongfang zone.Secondly, study the controlling factors of reservoir properties. The reservoirproperties in Yinggehai basin has the three control factors: sedimentary facies,diagenesis and overpressurization. Found the favorable sedimentary facies to affectthe physical properties; compared compaction, cementation and dissolution on reservoir properties; analysis of the mutual influence of the overpressurization on thediagenesis.That the small difference between the core porosity and permeability and thewell logging porosity and permeability, so well logging porosity and permeability canbe used as valid data to evaluate the reservoir; determine the porosity andpermeability of the lower limit in this studied area.At last, on the basis of factors in the study of All aspects of influencing factors inreservoir properties,reference to the geological background and sedimentary facies,pore types, physical properties conditions, classification and evaluation of themiddle-shallow reservoir in The Yinggehai Basin.