| Jiyuan oilfield is located in the northwest of ordos basin, it stretches across the Tianhuan depression and shanbei slope on the regional tectonic. The study area is located in the Wangpanshan area of Jiyuan oil field, which is still in the development stage of the evaluation at present. It is confirmed that the exploration and development of Chang 4+5 and Chang 6 reservoirs are full of potential. The chang 4+5 and Chang 6 reservoirs groups in the surrounding areas have a grand development scale, and the research is relatively deeper Otherwise, the exploration and development of chang 4+5 and Chang 6 oil reservoirs in the study area are in a relatively initial stage, the reservoir characteristics and accumulation law need to be further studied.This paper synthesized the latest research results in many fields, such as the tectonic evolution of the Ordos Basin, the basin burial history, the history of hydrocarbon expulsion of hydrocarbon source rock in Yanchang formation and petroleum migration of oil and gas, etc. On this basis, we investigate the Chang 4+5 and Chang 6 groups in Wanpanshan area of Jiyuan oil field by the latest multiple hydrocarbon accumulation technology. The study started from the research of sedimentary facies and focused on the analysis of reservoirs characteristics, thus predict favorable reservoir distribution area in the study area and provide the technical support for the following exploration and development,By making use of environmental knowledge, core and logging data of the sadhu, Chang 4+5 and Chang 6 oil reservoirs belong to the delta sedimentary system. In the study area, delta front subfacies deposits are mainly developed. Underwater distributary channel, mouth bar and distributary bay in the study area are the most evolutionary. Chang 4+5 and chang 6 reservoirs are further divided into chang 4+5], chang4+52,61,62,63 small layers, etc. On this basis, via ordinary chip, the casting thin sections, scanning electron microscope, physical property test data and macro distribution rule, the characteristics of chang 4+5 and chang 6 reservoirs are analyzed:the object of study overall belongs to low porosity and low permeability reservoir; the mainly reservoir rock type is Feldspar sandstone and lithic feldspar sandstone. The feldspar lithic sandstone is in a small amount. As a whole, petrological characteristics showed diagenetic minerals feldspar. The main filler content ingredients are chlorite membrane, illite and kaolinite; The main diagenesis in study area includes compaction, cementation (metasomatism) role and dissolution; Native hole in the study area is given priority to residual original intergranular pore, the corrosion hole is secondary preference, followed by relatively few micro-crack. According to the reservoir pore and throat grading standards in this area, in combination with the reservoir pore structure data of Yanchang group, the study area give priority to fine holes micro-fine throat. Finally, analyzed and summarized the accumulation rule and used the well test, production performance data, the structure characteristics of the top surface and reservoir characteristics of sand body, the oil and gas distribution of the study area is mainly controlled by sedimentary facies; bay between distributary mudstone is the main condition of oil and gas reservoir lateral occlusions, which is a necessary condition of oil and gas enrichment and main space of dissolution pores oil and gas reservoir; in addition, oil and gas distribution is controlled by fracture. It is indicated that chang 4+522、chang 611 and chang 612 are relatively developed as a whole, and are the most favorable objective horizon in the study area. The rolling extension can continue to be developed.In conclusion, studying chang 4+5 and Chang 6 oil reservoir characteristics of this area, looking for favorable zones and carrying out effective exploration and development technology is with guidance on the next block exploration and development. |
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