Second Member Of The Shahejie Formation Sand Lixian Slope To The Sand At The Period Of Provenance Analysis And Characteristics Of Sedimentary Facies

Lixian slope lies in the west of Raoyang sag and is close to the source rock which is the direction of oil and gas migration, the conditions of oil source is advantageous there. In recent years, Lixian slope is the key area of exploration, and Shahejie formation is the target layer, but the material source is still controversial. In this paper, by using ancient river system comparison, heavy mineral analysis, and detrital minerals analysis initially, combining the logging data, the material source direction of Sha-2section and lower Sha-1subsection have been clear in sedimentary period. This region have been affected by two material sources, one of which comes from west and southwest of Taihang uplift while the other comes from north of the low uplift in Niutuo village. In addition, the influence from buried hill in the east of the field is proposed firstly.Based on the summary and analysis of previous information, Sha-2section and lower Sha-1subsection of Shehejie formation are divided into sequences systematically in this paper. By using sedimental theory and observed well cores, combining logging facies, three types of sedimentary facies in this area which inclduding fluvial facies, braided delta facies and lacustrine facies develops in this area. All of them are further subdivided into5kinds of sub-facies and12kinds of micro facies.Based on single well analysis, comparison of collecting wells, thickness isopleth map of sandbodies, and on the guide of sedimental model, a sedimentary facies map is made by using ascending half cycle units and descending half cycle units of fourth-order sequence, consequently, the evolution law of sedimentary facies was studied. At the period of Sha-2member in the region, braided fluvial river and braided river delta are developed extensively, sedimentary facies zone spread from west to east, sediments become tiny, and the types of sedimentary change from braided fluvial river to braided river delta regularly. At the period of lower Sha-li member, shore-shallow lake facies and Semi-deep lake facies are major in the area, and shore-shallow lacustrine beach bars develops, braided river delta retreat back to the north of Gaoyang and the southwest of Boye. At the same time, sedimentary facies zone spread from west to east, the types of sedimentary change from braided river delta to lacustrine facies regularly.