Injection Well – Producer Well Combinations in Application of Toe-To-Heel Steam Flooding (THSF)

Abstract

Abstract Toe-to-Heel Steam Flooding (THSF) is a new, short-distance thermal EOR process that achieves high recovery by virtue of its stable front propagation and producing mobilized oil directly into an active section of the horizontal producer. However, the wells configuration design for field development purposes still requires critical attention so as to ensure less environmental effect, efficient start-up and optimal oil recovery. We present a series of 3-D simulated experiments using our developed PVT and rock model for KEM heavy oil reservoir in Iran to study the feasibility of THSF. Model has been validated with the published experimental observations. Then, different well configurations using Vertical (V) or Horizontal (H), Injector (I) and/or Producer (P) in direct line drive (VIHP, HIHP) or staggered line drive (VI2HP, 2VIHP) have been investigated. The results show that THSF outperforms the conventional steam-flooding (VIVP). Different wells configurations of THSF showed superior performance over CSF in low-permeability KEM reservoir. A quasi-vertical steam condensation front exists that moved along the horizontal section in a toe-to-heel manner. Contrary to CSF, there was no or negligible steam override and channeling in different THSF configurations. Also, the horizontal injector configuration (HIHP) was the most efficient configuration for achieving rapid start-up, i.e., the shortest time to achieve stable front propagation. The single vertical injector configuration (VI2HP) was initially slow to achieve stable operation, due to the development of a much smaller steam zone. As the process continued, 2VIHP provided improved vertical, areal, and volumetric sweep efficiency associated with steam condensation front, which resulted in larger steam chamber and higher ultimate oil recovery. Finally, the sensitivity of THSF performance to the length of horizontal producer and traversal distance between producers (for VI2HP) or between injectors (for 2VIHP) has been simulated. These results indicate the optimized scenarios for the field development purposes.