Study On The Features Of Petroleum Geology Of West Canada Sedimentary Basin

With the increasing demand for hydrocarbon,our country has been attaching more importance to the survey and study for Paleozoic carbonate reservoirs.The Western Canada Sedimentary Basin,which includes the Alberta Basin and the Williston Basin,stretches across the United States and Canada and contains ample petroleum resources of carbonates.The Alberta Basin belonged to passive margin basins before Middle Jurassic and Williston Basin belongs to intracratonic basins.Thus it is of certain referential values for our exploration of carbonate fields to study carbonate reservoirs in these two basins.Based on collection,arrangements and translation of massive foreign documentaries and data,this article analyses and summarizes carbonate facies patterns,features of diagenetic evolution,characteristics and conditions of hydrogen accumulation in two basins,obtaining conclusions as follows.(1)In the stage of passive margin basin,all kinds of carbonates from coastal environment to relatively deep environment had developed in the Alberta Basin,among which reefal carbonates is richest.However in the Williston Basin,its water depth remained relatively shallow with relatively weak hydrodynamic force,mainly carbonates of ramp facies had developed.(2)The influence of diagenetic evolution and fracturing is of great importance to the quality of carbonate reservoirs.In many cases,they may reverse the porosity and permeability.(3)Many resource rocks have formed during the period of passive margin and mature resource rocks are largely distributed in the Foredeep Belt.Thus carbonates of reefal and bank facies is the most favorable reservoirs in the Alberta Basin.In contrast,resource rocks in the Williston Basin are not only fewer in number but poorer in quality with mature resource rocks distributed in the central basin.Thus,anticlines in the central region of the basin are favorable areas for hydrocarbon to migrate to.However,their reserves are much fewer than that of the Alberta Basin.(4)Under the influence of foreland tectonic movement,there are structural trap being formed in the Alberta Basin,while in the Williston Basin,complex combined traps developed most and for most of traps,depositional change is a key element.