Application of Multi-Stage Fracturing of Horizontal Wells in SAGD Technology
Abstract
SAGD process is used in reservoirs with continuous sand body and high vertical permeability. In western Canada, most of top tier SAGD candidates have already been developed. Many lower tier pools with interbedded shale layers (such as IHS) are available in which current SAGD practices may not deliver an efficient recovery method. The suggested method is to perform a multi-stage fracturing treatment on the injector to open up barriers with vertical hydraulic fractures before steaming. If successful, steam can pass through the barriers, effectively heat the otherwise isolated oil and recover it.
This research has two major components. First, the flow mechanism and recovery response of a fractured SAGD well are discussed to show that the suggested process can improve production rate and recovery factor. The desired fracture properties and expected production rates are obtained by using analytical and numerical reservoir engineering techniques. Through numerical simulation, a matrix of sensitivity cases is made on key fracture parameters. It is shown that fractures with short half-length but high conductivity are required. Using the sensitivity results, an optimum range of the key fracturing parameters and general design criteria are determined using a new dimensionless fracture conductivity definition.
In the second part, some geomechanical topics to be encountered are discussed, starting with a review of relevant hydraulic fracturing field trials in oil sands. Some interface crossing criteria are reviewed and the extended Renshaw and Pollard criterion is used to study fracture propagation through sand-shale interfaces. These results are then compared to results from a coupled reservoir-geomechanics-fracturing simulation software. It is shown that tensile hydraulic fractures can be created in the oil sands, and fractures can cross sand-shale interfaces and be filled with desired concentration of proppant. It is also shown that small but high conductivity fractures (required for success of the proposed method) can be generated by using currently available proppants and fluid systems. The design considerations for various liner systems that can combine fracturing process and SAGD phase are discussed and a few new designs are proposed. Finally, a step by step roadmap for field implementation of this novel method is presented.
Description
Keywords
Engineering--Petroleum
Citation
Saeedi, M. (2016). Application of Multi-Stage Fracturing of Horizontal Wells in SAGD Technology (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/24965