Feasibility of the Gas and Downhole Water Sink-Assisted Gravity Drainage (GDWS-AGD) Process to Enhance the Recovery of Oil in Reservoirs with Strong Aquifer

Document Type

Article

Publication Date

1-1-2021

Abstract

The hybrid process of gas and downhole water sink-assisted gravity drainage (GDWS-AGD) was efficiently adopted to improve oil recovery at a saturated oil field, namely the PUNQ field. The PUNQ field has an infinite active aquifer with very strong edge and bottom water drives. A black oil reservoir flow model was implemented for carbon dioxide (CO2) flooding simulation of the GDWS-AGD process for comparing its performance with the gas-assisted gravity drainage (GAGD) process. The comparison was performed to obtain the most straightforward information on the performance of the combined GDWS-AGD process. Next, both the design of experiments (DoE) and proxy modelling were incorporated to find the most sensitive parameters that affect the GDWS-AGD process performance. The candidate parameters were porosity, horizontal and vertical permeability for each layer, the aquifer’s radius and rock compressibility. In the GDWS-AGD process, the produced water reduced water cut and coning and significantly reduced the reservoir pressure, resulting in improving gas injectivity. Besides, the GDWS-AGD process improved cumulative oil production. More specifically, the results showed that cumulative oil production increased from 3.8 × 105 m3 to 4.7 × 105 m3, and water cut decreased from 97 to 92% in all the horizontal oil producers. The proxy model was cleared from Sobol analysis that the porosity for layer 5 was a more influential parameter than others on cumulative oil through the GDWS-AGD process, with 31% main effects and 0.025% interaction effects. In comparison, the horizontal permeability for layer 4 was the most influential parameter with 24% main effects and 1.5% interaction effects. The novelty of the GDWS-AGD process comes from its effectiveness in improving oil recovery by reducing the water coning, water cut and improving gas injectivity, which ultimately leads to more economical implementation, especially with respect to the operational surface facilities. The use of GDWS-AGD process can help the operators in extracting hydrocarbons in a more efficient and greener manner.

Publication Source (Journal or Book title)

Green Energy and Technology

First Page

91

Last Page

106

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