A New Approach for Interpreting Pressure Data To Estimate Key Reservoir Parameters From Closed-Chamber Tests

摘要

A new technique for analyzing and modeling the pressure data from both flow and buildup periods in closed chamber tests (CCT) has been developed. It can be used for estimating the key reservoir parameters such as reservoir pressure, permeability and skin. There are two aspects of the proposed approach - straight-line analysis and modeling. A novel approach is taken to develop the analytical solutions and procedures for both liquid and gas wells. Approximate solutions for the early-time and late-time pressure behavior are derived from the rigorous solution and are used for developing the basis for the straight-line analysis. A derivative function is utilized to ascertain if the data contains any portion of reservoir-dominated flow. Two synthetic data examples are presented to illustrate the process. Important contributions made in this study are as follows: 1. The analysis procedure is simple enough to implement in a spreadsheet, but is more accurate than the currently available methods. 2. Calculating influx rates during the drawdown period is not an essential part of the analysis or modeling. Thus, any noise in the data would not aggravate the accuracy of calculations. 3. The complete analytical solution for modeling the entire CCT data will allow one to investigate possible test durations for CCTs, and also to refine the parameters determined from approximate analyses. The presented technique is also applicable for analyzing drillstem test (DST) data, as long as the flowing fluid does not reach the surface.