Transversly Multi-Fractured Horizontal Wells: A Recipe for Success

Abstract

Abstract While the hydraulic fracturing of vertical wells is perhaps the most widely used method for production/injection enhancement in the petroleum industry, the fracturing of horizontal wells has been used sparsely, mostly in the United States and the North Sea. Usually this involves either longitudinal fractures or treatments with no regard to the well orientation and fracture azimuth. The systematic transverse fracturing of horizontal wells poses several challenges in design and optimization and in operations and execution. A multi-fracture design and a feasibility study are performed to identify candidates for both a technical and an economic success. We used a fractured vertical well as the basis of our calculations and we have determined the dimensionless PI as the means to evaluate the attractiveness of multiple transverse fractures intersecting a horizontal well. In previous publications we have presented the Unified Fracture Design and how its adaptation by several companies and researchers led to major new successes. The drainage shape and flow regime in transversely fractured wells differs significantly from vertical wells. The Unified Fracture Design had to be adapted with shape factors to account for the differences. We are showing a series of designs using a range of sizes of fracture volumes, different proppant types and drainage sizes. For treatment execution, traditional methods of perforating may increase the probability of failure. The types of reservoir which are candidates for these treatments such as multi-layered reservoirs will almost surely affect the fracture initiation, and, as usual, composite materials show higher mechanical resistances compared to homogeneous materials. A new abrasive jet cutting tool has now been designed and built specifically for this type of jobs. In this paper we will present all the design and operational challenges that will be faced in such fracturing project, and make recommendations for successful treatments