Horizontal wells have become the "industry standard" for unconventional and tight formation gas reservoirs. Because these reservoirs have poorer quality pay it takes a well planned completion and fracture stimulation(s) to make an economic well. Even in sweet spots in unconventional and tight gas reservoirs good completion and stimulation practices are required to achieve economic success. But what are the objectives of horizontal wells and how do we relate the completion and stimulation(s) to achieving these goals? How many completions/stimulations do we need for best well performance and/or economics? How do we maximize the value from horizontal wells? When should a horizontal well be drilled longitudinally or transverse? These are just a few questions to be addressed in this paper.

This paper focuses on some of the key elements of well completions and stimulation practices as they apply to horizontal wells. Economic optimization studies were conducted for tight gas reservoirs highlighting the importance of lateral length, number of fractures, inter-fracture distance, fracture halflength, and fracture conductivity. In addition to the tight gas completion and stimulation considerations, network complexity will also be considered. These results will be used to develop a horizontal well decision tree for evaluating the various drilling, completion, and stimulation issues encountered in horizontal wells in tight and unconventional gas reservoirs. Field examples will be used to highlight these strategies.

This work benefits the petroleum industry by:

  1. Developing well performance and economic objectives for horizontal wells and highlighting the incremental benefits of various completion and stimulation strategies,

  2. Establishing well performance and economic based criteria for drilling longitudinal or transverse horizontal wells,

  3. Integrating the reservoir objectives and geomechanical limitations into a horizontal well completion and stimulation strategy,

  4. Developing a horizontal well completion and stimulation decision tree for pre-horizontal well planning purposes.

Keywords:
unconventional gas reservoir, complex reservoir, completion, permeability, directional drilling, hydraulic fracturing, objective, spe 137839, year rate, upstream oil & gas
Subjects:
Drilling Operations, Hydraulic Fracturing, Unconventional and Complex Reservoirs, Directional drilling, Shale gas
Copyright 2010, Society of Petroleum Engineers
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