Fine Stratigraphical Division And The Study Of Sedimentary Characteristics Of Es₂^下 Strata Of Shanghe Third Area

Shang Third Area lies in the south of Shanghe Field,and is part of Lin-Shang broom fault structure system of Huimin sag central uplist of Jiyang depression in Bohai Bay basin. With the improving of mining level and the contradictions continuously emerging, the oil developing becomes more and more difficult, and the field area has been into an extra-high watery stage. For such problems, basic geological studies of the field is necessary. This paper maked the southern block of Shang Third area as the object of the study, and the main contents contains fine stratigraphical division and the sedimentary characteristics research.(1) Based on the rules of tisochronism, sedimentary facies control laws consistency and depositional cycles consistency, divided Es2下strata of Shang Third Area southern block into five sand formations and thirty-nine layers. And according to equal elevation patterns, contrast model of overriding sand bodies and contrast model of facies change, carried out the work of stratigraphic division and correlation against Es2下strata of the studying area, this paper established stratigraphic framework model of the whole area.(2) Making analysis for lithologic features, sedimentary tectonics, particle size characteristics and electrical properties, determined the related facies marks, and drew up some single-well sedimentary facies figure. And summarized that three kinds of subfacies exist in the studying area, i.e., the delta front subfacies, the prodelta subfacies and the sallow lake subfacies. The sedimentary microfacies includes river mouth bar, distal bar, tributary bay, prodelta mud and sallow lake mud.(3) On the basis of analysis for single-well facies and wells correlation, the paper identified the plane features of various facies for every layer. Concluded that during the sediment period of 5 sand-bed and layer 2of 4 sand-bed, the studying area is in a lake-regressive condition, i.e., delta facies continuously developing while lake facies unceasing regressing, and it is another lake-regressive condition during the sediment period of layer 1 of 4 sand-bed and 1 layer of 1+2 sand-bed. (4) Making clear of the sediment provenance and the sand-body exhibition rule, setting up the depositional model. Considered that the Es2下sediment provenance of the studying area, on the whole, is west or northwest direction, and part is south direction.