Study On The Main Controlling Factors Of Sandbody Deposits In Huanian-Heshui Area

The petroleum exploration in Ordos Basin has got remarkable achievements in the past 20 years,and the key points of petroleum exploration targets have also expanded from structural reservoirs to lithologic reservoirs.Different from structural reservoirs "finding high points",the key to lithologic reservoir exploration is prospecting sandbody's position and extent.In recent years,the discovery of Xifeng field,a 100 million tons petroleum field,has established the southwestern petroleum enrichment area of the Ordos Basin,and has proved that the Chang 8 oil-bearing formation has great petroleum exploration potential in the vertical direction.The Lake Basin was expanding in chang 8 period.It not only rich in provenance,develop braided river delta depositional system,but also had been gentle and wide,therefore,being suitable for the development of beach-bar deposits.In recent years,the study of Chang 8 reservoir sandbody mainly takes the braided river delta sedimentary model as the guidance,and focuses on the prediction of delta-front sandbody.There are few studies on the beach-bar deposits.It is of great academic significance to study the deposition of the 8 beach-bar deposits and explore the main controlling factors for the development of the beach-bar sand bodies.It also has important reference value for regional petroleum exploration.Through the combination of light and heavy mineral analysis,Chang 8 oil-bearing formation in Huanxian-Heshui Area had been mainly controlled by the Western sedimentary system and southwest sedimentary sedimentary system.Outcrop,core,logging data have confirmed that the beach-bar sand widely developed and their thickness is sizeable(2~4m,the thickness of up to 10m),common parallel bedding,wave ripple cross bedding,trough cross-beddin,tabular cross bedding;logging response performance in high amplitude infundibuliform,this distinct features is easy to identify.Through the establishment of high precision model,restorate the fluctuation features of the ancient lake basin,which found that the position of beach-bar sand in Yanwu area is mainly controlled by the western fan delta sedimentary system,developed on both sides of fan delta;because of two micro channel on Chongxin--Zhenyuan?Jingchuan-Qingyang,southwest provenance can pour in basin,the beach-bar deposits in MaLing area had been influenced by West and southwest of sedimentary system at the same time,continuous development in MaLingQingcheng-Heshui line;the beach-bar deposits in Huachi area,due to ups and downs of the lake basin,distributed along the micro ridge,the authors point out that the provenance and lake basin bottom shape jointly control the distribution of beach-bar sand bodies of Chang 8 oil-bearing formation.