Gel Flooding Pilot Test and Evaluation Method Studies to Control Water Channeling in Conventional Heavy Oil Reservoir of Bohai Bay

Abstract

Abstract LD oilfield was put online in Bohai Bay of China in 2005, characterized by huge thickness, high permeability, severe heterogeneity and high crude oil viscosity(210~460cp).Water injection in this oilfield was initiated in 2007. There are many challenges during water injection because high oil-water viscosity ratio leads quick breakthrough of injecting water, and high increasing rate of water cut, and so on. In order to solve these problems, the gel flooding pilot test was conducted in LD oil field during the year 2009 to 2010. Before pilot test, laboratory study under field conditions was conducted to determine the chemical parameters of the gel injection. We also did numerical simulation study with CMG STARS. A range of variation of critical parameters was evaluated in the simulation for understanding the gelation process in the reservoir. The model was used to predict the reservoir response under different gel chemical parameters. Results from simulation showed that water cut reduced from 15.9 to 36.6% which matched the trends observed in wells. On other hand, dynamic method is also used to evaluate the gel pilot test. The Hall curve analysis was used to evaluate the effectiveness of the injection well and to calculate the resistance factor(RF) & residual resistance factor (RRF) (RF from 4.11 to 6.88, and RRF from 3.18 to 7.97 in LD oilfield). The decline curve analysis was used to obtain net incremental oil by gel injection treatment. Results from two well patterns conducted gel pilot test in 2009 indicate that water cut reduction ranged from 3.2 to 36.8% and average oil production increases 14.7 m3/d. Based on results, another pilot test with two new well patterns were conducted in 2010 and we are now evaluating the new pilot test. The pilot test & evaluation technology provides the foundation for promoting application of techniques to stabilize oil rate and control water production in reservoirs with conventional heavy oil in Bohai Bay of China.