Perpustakaan Digital ITB

Pressure transient analysis of vertical well with finite conductivity fractures is presented that uses Tiab’s Direct Synthesis (TDS) technique as its basis for calculations. In this technique, log-log plots of pressure change and pressure derivative data of a pressure drawdown or pressure buildup test are analyzed with direct analytical solutions. The results are compared to the previous method which uses the type-curve matching method in Saphir 3.20 program and specialized lines feature also in Saphir 3.20 program. The approach is based on the presence of several straight lines corresponding to different flow regimes when the pressure change and pressure derivative data are plotted on a log-log plot. The slopes and points of intersection of these straight lines are unique and therefore can be used to calculate several reservoir, well, and fracture parameters. These characteristics features can be used both for calculation and verification of the value of parameters using a direct analytical solution that shows a satisfying result. Four details examples and solution procedures are presented with one example is from synthetic data generated by Saphir 3.20 program which aim to verify and compare the result of the proposed method to the previous method uses in Saphir 3.20 which are type-curve matching and specialized lines feature, the other three examples use the real field data in Jambi, Indonesia. After the TDS technique results are compared to the type-curve matching model and specialized lines result, it shows quite similar value obtained from both the TDS technique and Saphir 3.20 program. The big difference appears on skin factor value that causes by the inability of Saphir 3.20 to produce the negative skin factor value for every data analysis which leads to the different value resulted from half-fracture length or fracture conductivity. However, the permeability and wellbore coefficient values show a good comparison to Saphir 3.20 program. At this point, the power of the TDS technique on calculating and validate the parameters has already proven. The proposed TDS technique to interpret pressure behavior is practicable and accurate since it can solve the problem from the previous method approach.