Tight gas formations bounded by base rock and/or overlain by an overburden rock, that are not barriers to vertical fracture migration, are not amenable to "successful" large stimulation treatments by hydraulic fracturing as practiced today. Reservoirs of this nature are abundant. The example to be considered here is the North Douglas Creek Arch Field, east of Rangeley, Colorado. The objective of this paper is to present the preliminary findings of a project sponsored by the Gas Research Institute of Chicago and conducted by Terra Tek, Inc. of Salt Lake City and Chandler & Associates of Denver. The program is aimed towards developing technology that can provide deeply penetrating fractures in formations lacking barriers to vertical migration.

Four prospective techniques are being evaluated in the laboratory and in the field: fracture initiation placement (perforation placement), fracture packing with lightweight additives, controlled process zone fracturing, and electrical heating/fracturing followed by hydraulic fracturing. Each of the techniques is being evaluated for feasibility by analysis and tests performed in a polyaxial test machine that is capable of accommodating rock samples one cubic meter in volume. The program intends to validate and optimize the most effective technique in the field. It is anticipated that the optimum technique will probably be a combination of the several proposed techniques. The program includes stimulation technique evaluation in four new wells in the North Douglas Creek Arch Field.

Among the work reported in this paper are: preliminary studies related to the development of the four different techniques, fracture geometry prediction under adverse stress distribution condition, and drilling, coring, drill stem testing, transient pressure testing, in-situ stress measurements, log analysis, and routine and special core testing on core materials from two of the new wells.

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