Research Of Sedimentary Characteristics Of 4th Member Of Shahe-jie Formation In DongFengGang Oil Field

There are many geology problems present such as stratigraphic division, division of sub-bed and monosandbody and reconfirm of sedimentary microfacies, although DongFenggang is in middle period of development of the oil field. The reconstruction of stratigraphic framework, depositional system, depositional model and the regularity of sand body were researched in the paper, through the research on sedimentary characteristics, from several aspects, providing a scientific reference for the further water-flooding justification and development. The main outcomes are as follows:①Geologic models were built, which could make down the objective situation underground, providing significant basis for comprehensive evaluation. Series of strata and sub-beds were division. Srtratigraphic framework was rebuilt too at the same time.②The lithologic characteristics, sedimentary structure, size characteristics and electric properties were analyzed. The sedimentary facies indicators were defined and the deposition phase diagrams of single well were drawn.③The results indicate that during the deposition of upper 4th member of Shahe-jie formation, there are three types of intrafacies: delta plain, delta front, littoral and shallow lake. The favourable sedimentary microfacies are distributary channel, distributary mouth bar and distal bar.④The distribution characteristics and vertical evolutions of sedimentary facies in two-dimensional space were defined. From the 3rd sand set of upper 4th member of Shahe-jie formation to the 1st the overall performance of the area was lake transgression. The sandbody connectivities were better in north-south than in east-west. ⑤The development of ancient watercourses, paleocurrent directions and the evolution of the sedimentary facies were defined. The paleocurrent directions were changing during upper 4th member of Shahe-jie formation, from one-direction to multi-direction to double, the direction of Wudi uplift was always the main. The types of the intrafacies and the microfacies on horizontal were more than on vertical, the changes of the facies were faster too. Based on the appearance of the delta plain of the 3rd sand set of upper 4th member of Shahe-jie formation and the appearance of the littoral and shallow lake of the 1st, it is show that during the formation the water level rose, lake intrusion⑥The distribution of provenance and the sand body and the depositional model had made. In the area the direction of provenance was from southwest to northeast. Among the many provenances, the Wudi and Yihezhuang uplift in the south were the main provenances. The direction of sand body distribution of the different sand sets was the same with the paleocurrent. The favorable exploration areas of the sand body were the distributary mouth bar and the distal bar whose sand body were thicker and lobate.