Session: 11-10-02 Development of Unconventional Reservoirs-2

Paper Number: 81340

81340 - Optimization of Oil Recovery and CO2 Sequestration in Tight Reservoirs During CO2 WAG Flooding With Hydraulic Fracture 

Objectives/Scope:  Tight oil reserves are an important oil exploration and development field in china. However, their primary oil recovery factor is less than 15% mostly due to the extremely tight formation and heterogeneity. CO₂ flooding is promising in tight reservoirs due to its high mobility and better injectivity than water. Water alternative gas flooding could improve sweep efficiency of gas flooding and oil recovery. However, its injectivity in tight reservoirs is limited. The feasibility of improving CO₂-water alternations performance in tight reservoirs by hydraulic fracturing was investigated in this study.

Methods, Procedures, Process: In this paper, numerical reservoir simulation was conducted to model CO₂ WAG flood process with typical reservoir and fracture properties from the YC formation. The optimization of hydraulic fracturing during CO2 alternative Water injection process were performed with numerical simulation, Response Surface and multiple response optimization method, which can be done with acceptable accuracy by performing a limited number of runs, hence, reducing the engineering time, effort and money. With the simplified equation between the NPV or CO₂ storage and different hydraulic fracture parameters, operators can determine the best combination of all the factors according different objectives.

Results, Observations, Conclusions:  The results showed that the co-optimization of recovery and CO₂ storage could be achieved under moderate fracture length, greater fracture height and low water gas ratio.

Novel/Additive Information:  This work can provide a better understanding of the physical mechanisms and key parameters affecting the effectiveness of CO₂ WAG flooding for enhanced oil recovery in the tight formation. It has explored a new road for increasing the recovery rate of unconventional tight oil formation.

Presenting Author: Baozhen Li CNOOC Research Institute

Authors:

Baozhen Li CNOOC Research Institute
Xiaodong Kang CNOOC Research Institute
Liqi Wang CNOOC Research Institute Co., Ltd
Jian Zhang CNOOC Research Institute Co.,Ltd.
Engao Tang CNOOC Research Institute Co.,Ltd.
Wensheng Zhou CNOOC Research Institute Co.,Ltd.