Method of Predicting Tight Gas Deliverability from Conventional Well Logging Data Based on Experimental Simulation

Abstract

Gas deliverability estimation is very important in predicting effective gas-bearing regions and formulating reasonable development program. Conventional deliverability prediction method based on absolute open flow cannot be used in exploration wells due to the important input data of drill stem test (DST) data that cannot be first acquired. In this study, to establish reasonable model to predict exploration well deliverability, four core samples, drilled from the same tight sandstone reservoirs of northeast China, are applied for deliverability simulation experiment under formation condition. Gas flow rate and production data under different simulated drawdown pressures are acquired. A parameter of gas deliverability index, which is used to characterize gas production capability per well, is introduced. The relationships among gas deliverability index, reservoir physical properties (such as porosity, permeability and gas saturation) and drawdown pressure are analyzed. The results illustrate that for our target tight gas sandstone reservoirs, the optimal drawdown pressure is 5.0 MPa, and good relationship exists between gas deliverability index with the combined parameter of permeability and gas saturation. Based on this relationship, a model of predicting gas deliverability index from reservoir physical properties is established, and it is extended to field application to predict gas production. Comparison of predicted gas deliverability by using this model and acquired result from DST data illustrates the reliability of the established model.