Research And Application Of Logging Interpretation And Evaluation Model Of Fengcheng Formation In Mahu Sag

Accurate interpretation and evaluation of logging data is the key basis for the efficient development of unconventional reservoirs.Mahu sag in Xin Jiang oilfield,The paper research the sag of Permian Fengcheng group and complex causes: low porosity and low permeability reservoir,strong heterogeneity,fluid property discrimination often have deviation,log interpretation coincidence rate.The research improves the conventional logging interpretation,and has carried on the multi-parameter coupling logging evaluation model of exploration and practice,improving the precision of log interpretation evaluation in the region.The main work and achievements of this paper are as follows:Based on fully analyzing the geological background in the study area,this research gather a total of 88 for the collection of 50 well logging test analysis assay data,applying rock pyrolysis nuclear magnetic resonance(NMR)logging gas test,individual interpretation evaluation technologies,such as the curve of hydrocarbon pyrolysis chromatogram and the response characteristics of the nuclear magnetic resonance T2 spectrum,realized the qualitative criterion.On this basis,The research builds models that can distinguish the fluid properties are mined—the gas interpretation model of TC-Y,the geochemical pyrolysis model of ST*QZHB-S22/S11,and the nuclear magnetic resonance interpretation model.Among them,the gas measurement model and geochemical pyrolysis model can identify valuable and non-valuable layers with the discrimination rate of 79.5% and 78.52%,and the nuclear magnetic model can judge whether the reservoir is water-bearing,realizing the quantitative discrimination of reservoirs in this area.Although the single-item interpretation model can accurately judge the value layer or not,it can not be able to accurately distinguish the specific types of fluid properties.Based on this,the comprehensive interpretation model of the Fengcheng group is explored from the perspective of multi-parameter coupling.Based on Fisher’s criterion,the oil content index F1 and water content index F2 were obtained,and the index contained seven sensitive parameters of gas measurement and geochemical pyrolysis(B,Fj,R,ST*QZHB,Qh,Tc,S22/S11).The coincidence rate of the comprehensive interpretation model for the oil-water layer is 96.67%,the coincidence rate for the water layer and oil-water layer is 84.00%,and for the oil-water layer is 87.5%,realizing the fine interpretation and evaluation of the oil-water layer.The comparison and analysis of the interpretation coincidence rate of Mahu Fengcheng Group from 2019 to 2021 show that the coincidence rate of the comprehensive interpretation model is 42.9% without the use of the model,and 87.9%after the use of the model,indicating a significant increase in logging coincidence rate.At the same time,the application effect of the model analyzes two testing sections of two Wells in Fengcheng Formation in 2021.The feedback results show that the gas measurement model,geochemical pyrolysis model,and nuclear magnetic resonance model correspond well to the oil test conclusion.The comprehensive interpretation model is accurate to distinguish oil and water layers,which is consistent with the oil test conclusion.