An Introduction of MAINE Petrophysical Method; a Robust Solution to address Water Saturation Calculation in Low Resistivity Pay (LRP) Case, Offshore North West Java (ONWJ), Indonesia

Abstract

Low Resistivity Pay (LRP) reservoir is proven as an oil and gas reservoir in Offshore North West Java (ONWJ), Indonesia. This reservoir is characterized by high shale contain. Generally, the reservoir is deposited in shallow marine environment. The reservoir is fine grained with accompanied by either laminated, structural or dispersed shale matrix or its combination. This situation leads to the challenging in the petrophysical analysis in term of water saturation (Sw) calculation. These two elements is key parameter to calculate hydrocarbon in place. The objective of this paper is to propose a petrophysical method, called MAINE, to address the issue in this LRP reservoir. The analysis had been carried out from drill cutting and sidewall core data from the three wells in the interest area in the field. Core data had been investigated further to reveal the reservoir characteristic due to its resolution which much higher than the conventional log data and hence, it does calibration point. The MAINE method includes observation of high resolution of core sedimentology, clay distribution analysis, analysis of Porosity-Permeability-Irreducible Water Saturation Transformation (2PST) and Type Curve Analysis (TCA). This methodology will provide us the vertical geometry of LRP reservoir, clay distribution type, rock type, modified cementation exponent (m) and saturation exponent (n) related to its rock type and also more reliable water saturation. As the final steps and to gives the best results, this method has been validated by porosity-permeability relationship from core data. The MAINE Petrophysical Method yields more optimistic Sw calculation. Generally, there is an average of 23% decreasing in Sw calculation from 86% to 66% compared to the previous conventional log calculation, which is increase around 142% of oil saturation and it had been proven by well testing and dynamic analysis in the field.

AAPG Datapages/Search and Discovery Article #90354 © 2019 AAPG Asia Pacific Technical Symposium, The Art of Hydrocarbon Prediction: Managing Uncertainties, Bogor, (Greater Jakarta), Indonesia, August 7-8, 2019