Abstract

We present the use of fracturing technology to accelerate performance and improve ultimate recovery in heavy oil reservoirs. The applicability and efficiency of this approach were investigated by means of numerical simulation. A fully implicit 3-D thermal simulator was used to model the heat transfer efficiency and productivity enhancement when using this approach. Different scenarios were modeled for wells with horizontal and vertical fractures. This technology may be especially suitable for thinner reservoirs, dipping reservoirs and steam distillation drives.

The "heat plane source" concept is presented in this paper to explain the advantages of fractured steam injectors for improvement of thermal recovery processes. During steam injection, heat convection and gravity effects become dominant tn the near wellbore area causing excessive heat losses and poor recovery. We suggest an approach that will minimize convection override of the oil while creating a more efficient and stable steam drive.

Numerical results suggest that production response of current steamflood operations can be improved by inclusion of hydraulic fractures. Additional advantages observed for fractured injectors suggested a modified injection schedule that improves productivity and steam allocation for neighboring projects. This results in a faster return of investment and substantial increase in cash flow during the early life of the project. The economic benefits were evaluated by incorporating the production response into an economic model that maximizes the Return of Investment and Net Present Value.

Approach

The idea of using hydraulic fracturing for efficiency improvement of steam injection operations was a direct result of currently successful operations in the Kern River Field where FracPack's and Hyperstim techniques have proven to be effective solutions to severe sand production. Producer wells completed in this manner, periodically undergo steam stimulation treatments without sand flowback at the end of the steam cycling. Sand production decreased (minimizing revenue and production losses). Furthermore, it was observed that production response increased in wells under steam stimulation. This was even more interesting if we consider that this approach was applied in a reservoir not typically considered as a fracturing candidate.

The main objective and contribution of this work was to investigate the performance of hydraulically fractured wells and their advantageous application for thermal recovery processes in heavy crude oil reservoirs. Reservoir simulation was used to evaluate the suggested approach to accelerate recovery, improve steam management, effective development of depleted zones, target bypassed oil banks, steam assisted gravity drainage and alternative completions / recompletions. Numerical results indicate that inclusion of hydraulic fractures will ensue better steam utilization and sweep efficiency improvement while minimizing convective oil override and reduction of operational costs.

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