Advanced Formation Testing in OBM Using Focused Fluid Sampling for Producibility Evaluation in Mature Fields

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractWireline formation testing provides formation pressures, high quality samples and fluid identification/characterization. In addition, it can provide information for reserve assessment and producibility estimation.In this paper, we present comprehensive formation evaluation case histories with formation testing utilizing a focused sampling probe in wells drilled with Oil Base Muds (OBM) in mature fields. Due to OBM and low mobility sections, a new focused sampling device was utilized for effective formation testing and sampling purity. One case history demonstrates confirming remaining oil saturation. Conventional open hole and Nuclear Magnetic Resonance (NMR) logs were run for formation evaluation, and fluid saturations. Gas and remaining oil saturation were obtained from 3D NMR analysis. Sampling lab results and real time analysis of gas compositions are also compared for verification and confidence.Two field examples in low porosity/low mobility zones are presented showing the identification of mobile fluids. It is shown that the existence of mobile oil could have been missed without effective formation testing practices.The third field example of formation testing with low porosity as well as low resistivity is provided for the identification of mobile oil. Flow was enabled from low mobility zones along with low rate pumpout that would not be possible with traditional probe and pumpout devices.The final field example of water sweep evaluation in high permeabilitiy/mobility zones demonstrates using formation testing as a means of reservoir monitoring.