Interpretation of Drill Stem Test

Abstract

The behavior of pressure derivative analysis and pressure build-up analysis
expressed and discussed in this paper. Data from the drill-stem test report for field
example through closing the vertical well (Build-up period) analyzed using the
ECRIN KAPPA software. Build-up analysis used to estimate characterizations of
reservoir: permeability, initial pressure and skin factor. Pressure derivative analysis
used to know the type of flow regime, reservoir boundaries, wellbore storage and
other parameters. IPR compared with the Vogel method by calculating the
constants (0.084755, 1.4428*10-3, and -8.5207*10-7) to replace Vogel's equation
constants (1.8, 0.2 and 0.8). Abnormal point is located in a single phase region. Its
pressure is greater than that of the next point but its production rate is lower than
that of the next point. Productivity index calculated depending on the last
production rate. Good results are obtained of determination formation properties by
using drill-stem test data instead of production test data. Formation damage is
recognized from buildup analysis and constant wellbore storage, unit slope and
radial flow regime are recognized from pressure derivative analysis.