The Characteristics And Distribution Of The Granular Shoal Facies Reservoirs Of The Leikoupo Formation In Southwestern Sichuan

Aiming at the current situation that the research about carbonate grain bank reservoirs in the Middle Triassic Leikoupo Formation of southwest Sichuan Basin is still relatively weak.This thesis is guided by the theories and methods of carbonate sedimentary geology,reservoir geology and mathematical geology.And it focuses on the study of reservoir characteristics and distribution laws of carbonate grain bank reservoirs,in order to provide a reliable geological basis for the next exploration and development of Leikoupo formation in this zone.Based on the predecessors' studies of strata and sedimentary facies,this thesis multi-perspective analyses the conditions of grain bank formation and their main controlling factors.It is considered that the background of rapid transgression-slowly regression of sea contributes to the deposition of grain bank.The depth of 5 m of ancient water limits the development strati graphically of carbonate grain bank.The micro geomorphologic plateau of the inner platform provides favorable geomorphologic conditions for the development of grain bank.It points out that the vertical development of the grain bank in the inner platform has three parts,which can be divided into three sedimentary units.According to the study of basic characteristics of carbonate grain bank reservoir,we consider that the calciruditic dolomite and residual grain dolomite are the best reservoir rocks.Its pore types mainly include intragranular dissolved pore,intergranular dissolved pore and intercrystalline dissolved pore.The fractures of T213 is more than T2111.The reservoir has characteristics of "medium-low porosity and low permeability".The calciruditic dolomite and residual grain dolomite have better porosity and permeability correlation.The throat type includes the tracheal tube,the neck throat,and the lamellar throat of the residual granule.The reservoir of T2111 is the pore type reservoir with local development fractures.The reservoir of T2l3 is the fracture-pore type reservoir.And according to the main formation mechanism of reservoir space,the reservoirs of carbonate grain bank in the Middle Triassic Leikoupo formation can be divided into five genetic types.They are residual intergranular pore type,dolomite type,early karst type,buried karst type and compound type.Using the grey fuzzy comprehensive evaluation method,we can establish the quantitative evaluation model of carbonate grain bank reservoirs in the Middle Triassic Leikoupo Formation of the study area,which can implement the quantitative evaluation for the reservoir.And by the validating of production test,it indicates that the reservoir quantitative evaluation model has good practicability and maneuverability.For the fturther study of the distribution prediction of carbonate grain bank reservoirs in the study area,the result is carried out that ?+? types of reservoir maily distribute in Kongtan-Datachang well block and ?+? types of reservoir mainly distribute in the Maliuchang well block.