Sequence Stratigraphy And Favorable Reservoir Zones Prediction Of Shahejie Formation In Minfeng Area Of Dongying Depression

Minfeng area is located in the northeast part of Dongying Depression. Shahejie Formation is the major exploration target of Minfeng area. With the gradual deepening of hydrocarbon reservoir exploration, the exploratory objects gradually transfer to subtle reservoirs. So, more accurate research results of sedimentary facies and sand body distribution are needed to achieve reservoir prediction more efficiently.Based on the theories of sequence stratigraphy, sedimentology and hydrocarbon accumulation, sequence boundaries at all levels are identified with the combined analysis of drilling cores, seismic data and well-logging data. According to the contrast between drilling sequence and seismic sequence, the isochronous sequence stratigraphic framework of Shahejie Formation in Minfeng area is established. In the isochronous stratigraphic framework, the features and plane distribution of sedimentary system are studied. Combined with the analysis of reservoir forming conditions and source rock, reservoir-cap rock assemblage, favorable districts for the subtle reservoir are predicted.On the basis of the recognition of sequence boundaries, Shahejie Formation is divided into three second-order sequences and ten third-order sequences. The supersequenceâ… is composed of Sha-4 member; the supersequenceâ…¡is composed of Sha-3 member and lower Sha-2 member; the supersequenceâ…¢is composed of upper Sha-2 member and Sha-1 member. Through the analysis on a variety of facies mark, single well facies and profile facies, this paper comprehensively studies the sedimentary system types and the space distribution rules. It is known that sedimentary environments include lacustrine, alluvial fan, fan delta , nearshore subaqueous fan, braided delta, sublacustrine fan. And subsea distributary channel deposit of fan delta, braided channel and middle fan leading edge of nearshore subaqueous fan, subsea distributary channel deposit and channel mouth bar of braided delta, sublacustrine fan sand, beach-bar sand of shore-shallow lacustrine have good reservoir property. On the basis of overall evaluation of reservoir forming conditions and source rock, reservoir-cap rock assemblage, we can get the conclusion that Minfeng area has favorable formation conditions of reservoir such as plenty of oil sources, a variety of reservoirs, multiple sets of cap rock. Finally, the author pointed out that the steep slope of northen Minfeng area is the most favorable exploration zone.