Overview of a SAGD Reservoir Characterization Strategy for Horizontal Well Placement and Ranking Within the Surmont Lease, McMurray Oilsands, Alberta*
David Garner 1, TJ Wheeler 1, Emmanuel Mus 2, and Jean-François Richy 2
Search and Discovery Article #40166
Posted August 22, 2005
*Oral presentation at AAPG Annual Convention, Calgary, Alberta, June 19-22, 2005
1ConocoPhillips Canada, Calgary, AB ([email protected])
2Total, seconded to ConocoPhillips Canada, Calgary, AB
The McMurray Formation is a highly heterogeneous Cretaceous clastic reservoir with thick, bitumen-saturated sands. We applied a detailed quantitative workflow for integrating multi-scale data, building a geological model, and managing uncertainties associated with planning and controlling a steam chamber for SAGD bitumen extraction. Our main goals in this study were to aid and improve the complex decision making for vertical placement of horizontal wells, for optimizing expected performance, and for ranking of the horizontal well pairs.
Let us consider that the SAGD wells can be studied as individual reservoirs, with a drainage volume surrounding each well pair. There is a line of sight (LOS) along the length of the horizontal path or vertical plane and a width. Using the drainage volume and LOS, we calculated parameters such as effective well length, net-to-gross, facies proportions, producible volumes, and a vertical discount factor on stranded volumes for each model realization. A comparison was made to the purely deterministic geological approach.
The evaluation focused on the uncertainties in the estimated or simulated reservoir parameters. To decide on placement, post-processing of the detailed geostatistical simulations provided uncertainty measures on the reservoir parameters as a function of elevation. A probabilistic model was used to simulate well pair performance and rank the well slots. The model used well placements, extracted reservoir parameter distributions, SAGD operating conditions, and Butler theory in a Monte Carlo framework.
Innovative approaches were used to quantify risks and uncertainty, for consistency, and to make decisions from a complex set of criteria.
Our Team improved decision making by capturing many aspects of the Geological Model both Deterministically and Probabilistically.
The different Quantitative perspectives lead to optimized well placement scenarios.
We gained team effectiveness and partner alignment.