Reservoir Optimized Fracturing - Higher Productivity From Low- Permeability Reservoirs Through Customized Multistage Fracturing

摘要

Economic exploitation of low-permeability or tight sandstone and carbonates can be an elusive endeavor. New technologies and approaches are needed to make these more challenging reservoirs economically attractive. The completion technique discussed in this paper has been successfully employed in previously non-economic gas reservoirs in North America. The main focus of this completion technique is enhanced reservoir connectivity with the wellbore. Other completion techniques have previously been used to successfully improve reservoir contact and enhance production. These techniques are similar in their focus on improved reservoir connectivity by compartmentalizing the wellbore into multiple sections. They do, however, have their limitations in low-permeability or tight formations. The novel completion technique presented in this paper involves horizontal drilling through a reservoir combined with compartmentalizing the wellbore into multiple sections. Each wellbore section is then individually fractured in order to effectively propagate fractures through the reservoir, thus greatly increasing productivity in each zone. Up to twenty-four zones can be set up, allowing operators to customize their stimulation program in long-reach horizontals in heterogeneous and low-permeability reservoirs. Detailed knowledge of the existing natural fracture network, the current-day stress field, and geomechanical considerations are key inputs to a valid reservoir model, reducing the risk of establishing undesired flow paths with the aquifer, for example. This paper will illustrate how this new technology has enabled operators to benefit from significant economic improvements through operational efficiencies achieved during the drilling and completion phase based on reduced rig time and faster, more cost-efficient completions. Water shutoff options available with this new type of approach will also be discussed. Multistage fracturing leads to higher initial production, improved reservoir drainage, better control on fracture propagation, and controlled production from fractures in low-permeability sandstone and carbonate reservoirs as well as in gas-shales, which will be illustrated with case histories from these operating environments