Jonah Field Completions: An Integrated Approach to Stimulation Optimization with an Enhanced Economic Value
J. L. Jennings, B. P. Ault, 2004. "Jonah Field Completions: An Integrated Approach to Stimulation Optimization with an Enhanced Economic Value", Jonah Field: Case Study of a Tight-Gas Fluvial Reservoir, John W. Robinson, Keith W. Shanley
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Gas production in Jonah field is derived from more than 100 lenticular sandstone units that are interbedded with mudstones and siltstones over a 3000-ft (900-m) section of the Cretaceous Lance Formation. Productive sandstones average 12 ft (3.7 m) thick and are dispersed unevenly throughout the stratigraphic section. Historically, completion methods in Jonah have been costly and inefficient. Efforts to reduce completion costs while maintaining reserves in Jonah field required a new approach in evaluating and completing such thick productive zones. Analysis of fracture-simulation results for selected wells in the field suggests that stimulation of smaller, selected intervals would result in enhanced recovery by exploiting previously bypassed sandstone intervals. To obtain an optimal fracture-stimulation design, an enhanced petrophysical model was developed to provide reliable permeability, mechanical rock properties, fluid saturation, net pay, and net stress predictions. To further optimize the fracture stimulation, induced stress diversion was implemented. Induced stress diversion is a new technology that allows for multiple-stage stimulation without the use of a plug or mechanical device between stages. Using induced stress diversion, completion time was reduced by 4 weeks, and the percentage of producing sandstones in a treated interval increased from 60 to 90%. The net result was a 40% reduction in time and costs without negative impact on reserves. These optimization methods reduced development costs in Jonah field by 22%, from $2.8 million to $2.2 million per well, while achieving similar production and reserves.