Study On The Characteristics Of Chang 6 Reservoir In The Eastern Qujiagou Area Of Wayaobu Oilfield

The Chang 6 reservoir,located in the middle of the Wayaobu oilfield on the northern slope of the Ordos Basin and in the eastern portion of the Qujiagou extensional formation,is used as the research object in this paper.Issues like the lack of adequate research on the reservoir characteristics and the ambiguous distribution pattern of effective thickness are addressed.The study was carried out to investigate the rock characteristics,pore structure characteristics,physical characteristics,non-homogeneity characteristics,and the lower limit of effective thickness of the reservoir in small layers.It was based on sedimentary petrology,fundamental logging principles,reservoir geology,and other disciplines.It used logging data,core data,analysis,and assay data.Through this research,it was possible to learn the following:1.The principal material source for the Chang 6 oil formation is located in the northeast,and the delta front subphase and delta plain subphase were both produced in the Chang 6₁,Chang6₂,Chang 6₃,and Chang 6₄ formations.Traction flow deposition occupies most of the time.The majority of the reservoir clastic rocks in Chang 6 are gray-light gray feldspathic sandstone,and quartz predominates in the clastic particle percentage,followed by feldspar.The majority of the rock fragments are made up primarily of mica.2.The porosity of the Yanchang Formation Chang 6₁² in the study area is mainly distributed in the range of 8.5%～9.4%,and the permeability is mainly distributed in the range of 0.4×10^-3μm²～1.4×10^-3μm²;the porosity of the Yanchang Formation Chang 6₂¹ in the study area is mainly distributed in the range of 8.8%～9.6%,and the permeability is mainly distributed in the range of 1.1×10^-3μm²～1.9×10^-3μm².In turn,the pore-permeability rendezvous map was made and the correlation between pore permeability was found.Through the processing and analysis of the data,the porosity permeability models of Chang 6₁² and Chang 6₂¹ were established with good correlation,respectively.3.Among them,the intralayer non-homogeneity of the Chang 6 formation is generally strong,but the intralayer non-homogeneity of the Chang 6₁² and Chang 6₂¹ formations is weaker compared to other minor formations.Among them,the Chang 6₁² reservoir has strong to moderate intra-layer inhomogeneity and the Chang 6₂¹ reservoir has moderate to strong intra-layer inhomogeneity.Chang 6₁³ has the strongest interlayer non-homogeneity compared to other minor layers,Chang 6₂² has strong interlayer non-homogeneity,and the other minor layers have weak interlayer non-homogeneity.The Chang 6 planar non-homogeneity is generally weaker.4.By statistically processing the data and drawing the effective thickness distribution of different sub-layers of Chang 6,it is found that the effective thickness of Chang 6₂¹ is thicker than the other layers,and the effective thickness of Chang 6₁¹ and Chang 6₁³ is slightly thinner overall.The distribution of effective thickness can be seen more visually by observing the distribution map.