Dynamic Analysis Method For Evaluation Of Low Permeability And Sand Gas Reservoir

Well testing analysis technologic is a very significant method to realize and evaluate the reservoir as well as production control. By means of well testing for a gas well, we can analyze its production dynamic, predict its productivity and realize its formation characteristics. So the main work of this paper is to study the evaluation method for a low permeability reservoir by using the well testing analysis technologic for a gas well. Main contents of this paper includes:1. Dynamic analysis method for capacity evaluation of low permeability gas reservoir is studied in this paper. Present the basic principle and the applying condition for pressure drop-dawn method, pressure build up method as well as pressure differential method, and point out that pressure build up method is suitable for unstable flow stage, pressure differential method is suitable for transition stage, and pressure drop-dawn method is suitable for pseudo-stable flow stage.2. Dynamic analysis method for productivity evaluation of low permeability gas reservoir is studied in this paper. Present the choice method for different well testing means such as step-rate testing, isochronol testing as well as modified isochronol testing, and point out that modified isochronol testing is more suitable for the analysis of low permeability gas resenvoir with low productivity. This paper also gives the detailed step when we use the modified isochronol testing method to evaluate the low permeability gas reservoir.3. The well testing analysis method for determining the gas formation factor and single well controllable range is presented in this paper. Homogeneous and composite reservoir model for well testing was established, we also present type curve and take analysis of it. We gamed solutions to theoretical formulas under different boundary conditions, presented the method to determine the gas reservoir factor and single well controllable range by means of type curve.4. At last, we proved its applicable quality by means of analyzing the practical dada vwhich come from Sanzhan and Bachang gas reservoir.