Paper: High Proppant ConcentrationLow Volume Fracture Treatment Combined With Forced Colsure Yields Success In Clearfork Formation

Fracture acidizing and hydraulic fracturing utilizing propping agents has been used successfully in the stimulation of oil and gas wells for over 40 years. A tremendous number of these acidizing and proppant fracturing treatments have been conducted In carbonate reservoirs in west Texas. It is the purpose of this paper to report a fairly extensive program to optimize stimulation results, primarily in the Cleat-fork, but also In other west Texas reservoirs. The operator was noting declining production and wanted to institute a program to stimulate oil production but also at the same time attempt to control many of the operational problems typically encountered with proppant fracturing. The operator, when attempting restimulation, had seen little or no success over the years with many types of acidizing techniques. After several different approaches were taken in an attempt to solve the problem, we felt that utilization of high concentrations of high conductivity propping agents uniformly distributed across the producing interval was the answer to obtaining sustained productivity increases.lm7A lthough several proppant fracture treatments had been conducted in the area, we felt quite strongly that job design, job execution, and shut-in and flow-back procedures were inadequate to properly stimulate the reservoir. Our initial premise was to utilize as simple a fluid as possible, thereby eliminating job execution and fluid problems. We also wanted an efficient fracturing fluid with excellent proppant transport properties to be able to achieve a very high conductivity propped fracture. Additionally, we utilized the forced closure technique to minimize proppant settling in the producing interval. The authors felt that a major problem in the area was settling of the proppant into water-producing intervals in the lower part of the Clearfork. In the paper, we will give very specific examples of the use of intense quality control and also go into our evolution into the use of 35 lb/l 000 gal borate crosslink gels, as well as the very simple, straightforward polyemulsion system. We feel in both cases that the use of an aggressive proppant schedule, proper job design, and an aggressive flow-back schedule has allowed a very successful stimulation program to be accomplished. We will give extensive results on pre- and post-fracture productivity, as well as economics.