Improve Recovery Factor Of Ultra Heavy Oil By SAGD

This study takes Guantao reservoir in Block Du84 of Shu 1 area as the target block, analyzes basic data such production data, steam injection profile and logs, evaluates the producing status and residual oil distribution of cyclic steam stimulation by dynamic monitoring and numerical simulation, and clarifies the problems and potential of the reservoir; next, this paper deeply studies SAGD mechanism using physical modeling method based on investigation of the replacing method for ultra heavy oil-steam assisted gravity drainage(SAGD); then, SAGD reservoir engineering optimization is conducted by numerical simulation; finally, bulk development plan and index prediction are given for producing ultra heavy oil Shu 1 area with SAGD. The main research achievements are following:(1)Cyclic steam stimulation has shown low recovery factor and limited potential. It is an urgent need to convert development scheme.(2)Guantao reservoir belongs to massive reservoir with edge, top and bottom waters, humid fan sedimentation, with undeveloped intercalations, and contains ultra heavy oil.(3)The exploitation mechanism of SAGD has been understood through 2D and 3D physical modeling by temperature and pressure monitoring. Also understood are the formation and development of steam chamber in different stages.(4)The result of physical modeling indicates that SAGD is a feasible replacing method after cyclic steam stimulation for Guantao reservoir in Block Du84, and the recovery factor of SAGD may be approximately 60%, ultimate recovery factor over 75%.(5)Optimal reservoir engineering design of SAGD with combination of vertical and horizontal wells is conducted and provides technical support for field implementation.(6)SAGD deployment for entire Shu 1 area has been performed. 109 well groups are arranged, with predicted improved recovery of 29.95%. According to the oil sale price specified by PetroChina for economic assessment($40/bbl), the internal rate of return is 30.1%, which is higher than the 10% bench mark specified by the state and PetroChina, financial net present value is RMB 4.86866 billion yuan, and payback period is 6.9 years. The project will have certain economic benefit and is risk-resistance.