Research On Logging Evaluation Method For Tight Sandstone Reservoir Of Qianfoya Formation In Yuanba Area, Northeast Sichuan

Tight sandstone gas reservoirs have abundant reserves and great development value.With complicated geologicalconditions,such as low porosity and permeability,poor connectivity and so on,tight sandstone gas reservoirs are difficult for exploration and development.Logging reservoir evaluation,as an important part of the reservoir evaluation,is a key factor in the development of tight sandstone gas reservoirs.Therefore,this thesis takes the tight sandstone reservoir of Qianfoya Formation of Yuanba Area in Northeast Sichuan Province as research object.Aimed at the features of Qianfoya formation tight sandstone reservoir which have strong heterogeneity,thin reservoir thickness,produced both moisture and condensate and so on,this thesis performed the following studies:lithology identification,reservoir identification,reservoir parameter modeling and liquid properties discrimination.Based on the study of the reservoir characteristics and 4-property relationship,this thesis made an intensive study of lithology and reservoir identification of Qianfoya formation tight sandstone reservoir by using core data combining with conventional logging,the FMI logging and gas logging data.This research summed up a set of well logging and gas logging comprehensive mode for lithology and reservoir identification of tight sandstone reservoir.Using multiple linear regression method,this thesis carried on the modeling of porosity and permeability by each layers,and this model can give a rather accurate prediction.The water saturation of the fine sandstone reservoir with a low clay content was calculated by Archie Equation;and the water saturation of the siltstone,argillaceous siltstone reservoir with a higher clay content was calculated by the Simandoux Equation;furthermore the sand content estimation model was established by multiple linear regression equation in different layers.The moisture and condensate both exist in the studied reservoir.Diverse methods for recognizing the fluid properties with well logging mwell ethod and gas logging method were compared and evaluated.The study shows that the logging method does not give a good identification for oil and gas layer that only acoustic-neutron porosity overlap method and discriminant analysis method have a certain effect,while the parameter/plot identification method of gas logging can be well applied in different situations.The 3-H value,3-R value and C3/C2 specific value method performed the best identification results in the application.This research established a systematic and applicable evaluating model including lithology identification,reservoir identification,reservoir parameters calculating and liquid properties discrimination for the tight sandstone reservoir of Qianfoya Formation of Yuanba Area in Northeast Sichuan Province.And this thesis made a stable foundation for the further prospecting and exploration of the studying area.