In 1981, over 1,000 new wells were drilled below 15,000 feet1. Although bottom hole temperature in these wells vary widely, all have a number of similar characteristics which make hydraulic fracturing treatments very difficult. Completions in the Springer Trend in the Fletcher field are from 16,000 to 22,500 ft. The experience gained in the design and execution of these treatments should be beneficial to treatments in other deep fields.

The similarities of these treatments to other deep reservoirs include high bottom hole pressure and temperature, small diameter tubing, high closure pressures, low permeabilities, and tubing contraction problems while treating. The high treating pressures encountered necessitate the use of fluids with minimal pumping friction pressures. The high closure pressures often require the use of high strength proppants which are more difficult to transport than sand. Low formation permeabilities dictate the need for long propped fractures to achieve the desired production increase and thus long term treating fluid stability is required. To minimize contraction in the long tubing strings, treating fluids often must be preheated (100-140°F). The high initial fluid temperatures can alter fluid properties downhole.

Data and case histories will be presented to demonstrate the role various reservoir characteristics have on the design and execution of successful stimulation treatments. Examples of the problems to be addressed include high pore pressures which complicate drilling and cementing operation, unexpected fluid loss in stimulation treatments and the need for a more comprehensive pre-stimulation evaluation to identify candidates for hydraulic stimulation.

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