Quantifying feed zone contribution from pressure-temperature-spinner data and pressure transient analysis using WellTester

Abstract

Understanding the reservoir in a geothermal system is a key issue in sustainable production in a geothermal power plant. Modelling the pressure change during changes in injection or production gives a good view on how the reservoir responds. Quantifying the feed zone contribution in a flowing geothermal well is additional information useful in planning production in a power plant. The WellTester software is under development at Iceland GeoSurvey (ÍSOR) and is used to do the modelling of pressure transient analysis. The software was used to analyse the pressure response caused by changes in injection in well TW-4D, a production well in Bacman Geothermal Production Field in the Philippines, which is a part of a well completion test. The results are compared to the results from software called Sapphire. The results from both softwares are similar for the skin, injectivity index and permeability thickness. In addition, 3 production wells in the Philippines were studied with respect to flow capacity, namely well MY-1D in Northern Negros Production Field, well Pal-30D and well TW-4D in Bacman Geothermal Production Field, where spinner logs were used for estimating feed point contributions in a geothermal well. The results of the calculation of the flow capacity are estimated values for each feed zone for each well.