Some Aspects of Sand-Oil Fracturing in Long Heterogeneous Sand Sections

Abstract

On the northwestern coast of Peru, the International Petroleum Co., Ltd., initiated sand-oil fracturing in late 1953. As of May 31,1955,319 jobs had been performed in 61 of the 71 producing pools and in all eight of the producing formations. The wells treated have thick producing sections completed through gun-perforated casing, perforated liners, or combination strings.In the average treatment 300 bbl of refined oil was used to carry 18,900 lb of Ottawa sand; in most cases, the sand-oil mix was injected down the annular space. A bout 50 per cent of the jobs were done in wells where a thick series of sands and shales were exposed.Of the 319 jobs done, 70 per cent (or 271 jobs) were successful; the total additional oil produced of May 31, 1955, was 1,860,633 bbl and at that time additional oil was still being produced at the rate of 5,419 BOPD. Only the six most important producing sands are discussed in the paper. In one of these (Lower Parinas sand) a comparison was made between the results of nitroshooting and sand-oil fracturing. Composite production curves and typical electrical log sections are shown for each of the six sands. Also a statistical summary of results from all eight formations is presented.Variables which might have affected the success of treatments were investigated empirically and theoretically, but no satisfactory means 12 of predicting results of sand-oil fracturing was found. It was noted, however, that the beneficial effects were divided into three categories: induced fractures, elimination of well damage, and opening new reservoirs. The general conclusions were that sandoil fracturing was successful in wells where as much as 75 per cent of the exposed formation was shale, in old, apparently depleted wells, and that opening new reservoirs plus the elimination of well damage were important factors in the successes.