SINGLE WELL PRODUCTIVITY EVALUATION AND PREDICTION IN TIGHT CLASTIC RESERVOIR ROCK OF SHAXIMIAO FORMATION IN THE XINCHANG GAS FIELD,WEST SICHUAN

The gas reservoirs of Jurassic Shaximiao Formation in the Xinchang Gas Field of West Sichuan are typical low-permeability tight clastic ones.Due to complex geological conditions and strongly heterogeneous characteristics in this area,it is difficult to predict single well productivity.By analyzing logging information and reservoir physical property,we first extract 11 parameters related to productivity,such as interval transit time,fracture aperture,fracture permeability,etc.Second,with correlation coefficient method,6 productivity controlling characteristic parameters are determined,including fracture aperture,fracture permeability,productivity coefficient,fracture porosity,fracture developing index and composite evaluation index.Third,we select 33 tested wells as known samples,construct productivity forecast equation with the theory of support vector machine,and then get the standard error of 0.066 1 and the mean absolute error of 0.018 2.In the end,with the equation,we predict 24 untested wells to complete single well productivity evaluation of Shaximiao Formation.