Determination of pore size distribution profile along wellbore: using repeat formation tester

摘要

Permeability and porosity are essential properties of hydrocarbon reservoirs that are series to compute the production rates and the original hydrocarbon in-place. Permeability and porosity are often specified by the pore size distribution. Knowing pore size distribution along wellbore can greatly help us in determining perforating depth, mud, and cement type, etc. There are several experimental methods for determining pore size distribution such as capillary pressure measurements, but these methods are time and cost consuming. The goal of this study is to analyze repeat formation tester (RFT) data to determine pore size distribution profile along wellbore. By analyzing RFT data, reservoir pressure, fluids density, fluids contact, and capillary pressure were determined. Pore radiuses were calculated from capillary pressure, and pore size distribution was determined from frequency analysis of pore radius. On the other hand, mercury injection experiments were carried out on several core samples, and the results were used to determine pore size distribution from core analysis. At the last step, the pore size distribution obtained from RFT and core analyses was compared. Result of comparison shows acceptable accuracy of RFT pore size distribution.