Multidisciplinary Data Integration for Predicting Tarmat and Heavy Oil in Minagish Field, Kuwait

Abstract

This paper presents a multidisciplinary data integration in order to predict tarmat and heavy oil in Minagish Field. Techniques to detect tarmat are divided into those using logs and those which analyse the composition of oils such as Iatroscan geochemical technique; the later is very useful in detecting tarmat because of the remarkable difference in composition of oils in tarmat compared with the overlying reservoir. The second technique used is the pyrolysis method which detects mobile (Sr+S2a+S2b) and immobile (residual carbon RC) hydrocarbons along with TOC. It aids in identifying the nature of hydrocarbons within the pore structure defined by petrographic studies using polarized microscope and SEM. The samples were screened and analyzed using Rock Eval-reservoir methods in order to identify heavy and light hydrocarbon zones. The pyrolysis results show that there are many intervals of heavier oil intercalated with lighter oil ones. The previous studies of Minagish oil showed that this reservoir is richest in heavy polar compounds (26%) compared to other cretaceous reservoirs in Kuwait. Using the above methods, a new model is conceived with a clear variation in oil homogeneity vertically as well as laterally within the reservoir. In addition to that, faults and biodegradation near the water zone played their role in increasing density of oil and forming heavy oil in the reservoir. Application of magnetic resonance image and chemostratigraphic data are found effective in identifying heavier oil, light hydrocarbons and tarmat in real time mode. The chemostratigraphic interpretation draws certain depositional and/or diagenetic facies with definite elemental signatures. High P and P/Mn ratios are associated with oolite grainstones lithology that have high initial porosities and higher tar content. Also, tarmat is recognized by highly elevated values of Ni, V and S. This study led successfully to explain the production of an incremental volume of heavy oil trapped behind the injector in northeast area of the field.