(761a) Strategic Planning of Oil Sands SAGD Drainage Area Development Under Uncertainty

During the lifecycle of an oilfield project, development is the most critical phase due to intensive investments required for capital and operating costs. Determining whether it is economic to develop an oilfield or not and finding the best schedule for field development are the main concerns in this field of study. Alberta’s oil sands are the third largest proven global reserves of oil with current estimates of 26.6 billion cubic meters of crude oil. The majority of the oil sand deposits in Alberta Canada can only be extracted using in situ methods, mainly the Steam Assisted Gravity Drainage (SAGD). SAGD operations use super-heated steam to decrease the viscosity of the bitumen in the reservoir, such that bitumen can easily flow and be pumped up to the surface. A SAGD project normally targets the development of a number of drainage areas consisting of multiple injector and producer well pairs. Drainage area placement and development planning are crucial in a SAGD project.

Current practices of commercial placement of SAGD wells largely rely on reservoir characterization and engineering judgement. Optimization methods for the placement of SAGD drainage areas are relatively new in academia. Kumar investigated a space packing optimization method for generating a compact and non-overlapping arrangement of drainage areas [1]. Geometric transformations of global rotation, global translation and column translation were used by the space packing algorithm to maximize the recoverable bitumen. Restrictions such as non-placement of surface pads over surface restrictions or non-placement of drainage areas in thief zones were considered by incorporating a penalty function in the objective function. Manchuk and Deutsch used an adaptive grid search algorithm to determine the optimal arrangement of drainage areas [2]. The optimization algorithm determined the positions and orientations of the surface pads and drainage areas over a reservoir area to economically maximize the recoverable bitumen.

In this work, an optimization framework for planning the development of SAGD drainage areas under uncertainty is presented. The proposed framework includes the following major elements. First, an algorithm for compact drainage areas arrangement towards maximizing the amount of extractable bitumen is discussed. Second, a mixed integer optimization model is developed to arrange the multiperiod development plan of the drainage areas with consideration of capital and steam allocation restrictions [3]. Third, uncertainties in crude oil price and reservoir property are investigated based on a multistage stochastic programming model. The proposed method is applied to a case study with multiple drainage areas. The results demonstrate that the method can effectively generate a good drainage area layout and an economically optimal development plan that maximizes the net present value under crude oil price and reservoir uncertainty.

References:

[1] A. Kumar. Optimal drainage area and surface pad positioning for SAGD development. Thesis, University of Alberta, Canada. 2011.

[2] J.G. Manchuk and C.V. Deutsch. Optimization of Drainage-Area Configurations To Maximize Recovery From SAGD Operations. Journal of Canadian Petroleum Technology, 2013, 52, 233-242.

[3] H. Shahandeh, S. Rahim, Z. Li. Strategic Optimization of the Oil Sands Development with SAGD: Drainage Area Arrangement and Development Planning. Journal of Petroleum Science and Engineering. 2016, 137, 172-184.