The Research On Sedimentary Microfacies And Forcasting Perspective Of Chang 3 Reservoir In X259 Areas, LG Oilfield

In order to improve the effects of development in X259 well area of LG oilfield, the study of reservoir characteristics of Chang 3 oil group is needed. This paper focus on Chang 3 reservoir of Yanchang formation in X259 well of LG oilfield, we conducted a comparative study of stratigraphic division, a study of Chang 3 oil group of sand distribution characteristics and the micro structural features of Sand top, a study of the reservoir sedimentary characteristics, a study of logging secondary interpretation, the distribution the reservoir parameters, and the study of reservoir heterogeneity.The research shows according to sedimentary rhythm and sand distribution in the lateral, the Chang 32 oil group of the X259 well area is divided into three small layers, that is Chang 321, Chang 322, Chang 323. The sand thickness distribution characteristics shows that the sand distribution direction of three small layer of Chang 32 was southwest to northeast. Southwest and southeast of the study area are undeveloped the sand. The sand effective thickness of Chang 322 is most developed, and the distribution of sand is more stable. The study of micro structure features of the sand top shows that the structural features of the top of sand body as a whole was WSS-NE to monoclinic structure of the small layer of Chang 32, high in the east and low in the west, local exists the nasal swelling, Nose slot configuration features is significant. The sand top structure has a certain inherited characteristics and differences of Chang 321, Chang 322, Chang 323. The study of sedimentary characteristics shows that the sedimentary microfacies of small layers of Chang 32 include distributary channel between underwater, underwater natural levee and diversion bay. The Chang 32’develops underwater distributary channel microfacies, The Chang 322 develops underwater distributary channel deposit and diversion bay microfacies, The Chang 323 develops shunt between the Gulf and underwater distributary channel deposit. Three small layer thickness of sedimentary microfacies and sand comparison shows distributary channel microfacies of Chang 322 is larger, the ratio is highest. The average porosity of Chang 32 is 16.45%, the average permeability is 3.23×10-3μm2. Reservoir granule of Chang 3 is small, mainly fine sandstone. From the 4-Property Relationship study, we established a criteria of oil and water layer on X259 well area, from the perspective of the core scale logging, established log interpretation model of Chang 32 and completed logging data secondary interpretation. The established oil layer effective thickness the floor level of research area for:the porosity greater than 8% of Chang 32 oil layer, permeability greater than 0.3×10-3μm2, acoustic time greater than 217μs/m, resistivity greater than 23Ω·m. The study of reservoir heterogeneity shows that the development of reservoir is controlled by sedimentary microfacies and base level cycles.The reservoir heterogeneity of Chang 32 is medium, is the main oil formation. The distribution of porosity and permeability in this area is closely related to the distribution of sedimentary microfacies and sand body development. The sedimentary facies belts controls the permeability of reservoir.