Selection of Suitable Viscosity Reducer to Facilitate Test Production of Heavy Oil and Deep Reservoir

Abstract

AbstractExploitation of heavy oil from deep reservoir is often dictated by appropriate selection of viscosity reducer and artificial lift. For the proposed pilot in this study, it is necessary to identify suitable viscosity reducer to produce heavy oil from deep reservoirs, with down-hole electrical submersible pump (ESP). Broad field data of this reservoir are depth of 9300 feet, crude API gravity of 10 and crude viscosity of 10000 centipoise, at 4500 psi of SBHP and at 190 °F of BHT.The main objective of this study is to evaluate different viscosity reducer chemicals (VRC) for their efficiency in reducing the viscosity under severe reservoir conditionsSARA analysis was carried out on flashed crude oil sample to check the asphaltene stability of samples. Series of viscosity tests were conducted using an electro-magnetic viscometer in order to test performance of different viscosity reducers at diverse temperatures and pressures conditions.Experimental studies showed that as pressure decreases, viscosity of oil sample decreases with reduction in temperature. However, when the effect of different viscosity reducers on representative oil sample was studied, at 5000 psi and at reservoir temperature of 190 °F, it was noticed that reduction in viscosity of oil sample from 16,230 centipoise to less than 850 centipoise could be achieved.It is concluded from lab studies that reduction of viscosity of given heavy oil sample can be achieved with the help of suitable viscosity reducer to an extent, wherein, it is possible to operate downhole ESP and produce heavy oil from deep reservoir. Studies can also have practical application as an alternative planned production strategy to exploit such reservoirs. Study results definitely have far reaching influence to decide optimum dosage of viscosity reducer during execution. These studies can be seen as a representative model for performance comparison to test different viscosity reducers under diverse conditions. Studies also emphasized the need for carrying out meaningful lab studies for appropriate selection of viscosity reducers; while planning exploitation of heavy oil and deep reservoirs.