Research On Effects Of Hydrocarbon Emplacement To Diagenesis Of Reservoirs In Gutun Area, Ganguyi Oilfield

Guided by the advanced theory of sedimentlogy, in accordance with the macroscopic andmicroscopic methods, through the core observation, particle size and well log analysis, andcombined with background information on the regional deposition, to investigate thesedimentary characteristics of the Chang4+5，Chang6. Research has shown that reservoirs aremostly delta plain and delta front subfacies; the sand body is mainly water distributary channeland underwater distributary channel deposits. The oil and gas distribution of the study area aermainly controlled by sedimentary facies, delta sand body as the main development area, withthe thickness of the sand body, large-scale, uniform lithology, good physical properties, betteroiliness. Generally speaking，good quality sandstone distribution is favorable oil and gasaccumulation zone.The major reservoir lithology characters and diagenetic properties have been studied bymeans of the casting thin sections, scanning electron microscope. Studies have indicated thatChang4+5> Chang6member sandstone oil reservoir type is feldspar lithic sandstone. It hasexperienced strong diagenesis, strong compaction, strong cementation and strong dissolutionand metasomatism, and has reached a late diagenetic stage A. Compaction carbonatecementation of the pores have made the more serious damage. Dissolution properties of thereservoir have made some improvement，and metasomatism of the reservoir have not madeany change.An instance was analyzed, which of the relative content of minerals in the reservoir andthe variation in the stratigraphic section, to reveal lfuid-rock interaction characteristics ofYanchang formation of Ganguyi Oil Field Gutun area. Then, the control of hydrocarbon fillingto diagenetic evolution of the reservoir was discussed: the enlargement process of quartz inoil-saturated zone has been continuous after the charging of oil, but the process has beenrestrained in contrast to that in water-saturated zone; the late calcite cement filling werecontrolled; in oil-saturated or oil-rich zone, i I lite is relatively low, while in sands with smallamount of oil, such as the oil patch sands, or with only trace of oil and water layer, illitecontent is relatively high; feldspars and laumontite was relatively strong dissolved by organicacid in hydrocarbon, the secondary porosity was developed; and the buffering to compaction yielded under super pressure during formation of hydrocarbon.