Characteristics of Reservoir Sedimentology in the Sha-3(1) Member of Chengdao Oilfield

Key words: 
• braided river delta /
• reservoir sedimentology /
• evalu ation of prospecting area /
• Chengdao oilfield

Abstract: Based on the study of characterislies of reservoir petrology and sedimentology in target strata,the authors have put forward that the depositional environment of the Sha-3 member is river-shore shallow lake environment,the sedimentary sy stem belongs to lakeshore depositional system,and the sedimentary facies of the reservoir are braided river delta facies. The Sha-3(1) member is one of the most important reservoirs in Chengdao oilfiel d,sedimentary characteristics of which are very important for the rolling deve lopment and the evaluation of prospecting areas.The study concludes:(1) The rese rvoir of Sha-3(1) member is a set of coarse grain detrital sediment,belonging to river-shallow lake side depositional system with hraided river delta facies.(2) Massive gritstone,trough cross-stratification fine-middle sandstone,wave cross-s tratification fine sandstone and parallel-stratification fine sandstone are the most favourable petrofacies for petroleum accumilation;The combinations of Sf→M m,Sm→Mm,St→Mm and Sr→Sh are the most developed petrofacies combination type,and also the most favourable for petroleum accumulation.(3)The sedimentary der ivation is mainly northeast and southwest. The strelch of sedimentary facies,whi ch is under control of leetonics,goes north-northwest and south-southeast. The s edimentary province is geographically high in the west and low in the east,and high in the south and low in the north.