Results of Well Stimulation by Hydraulic Fracturing and High Rate Oil Backflush

Abstract

Well stimulation by hydraulic fracturing and by associated techniques has been carried out in fields along the Whittier fault trend in the Los Angeles basin since 1953, with a total of 53 jobs performed to date. The hydraulic fracturing methods of hydrafrac and sandoil frac have been tried extensively along with the stimulation technique of the "high rate oil back flush", which consists simply of injecting large volumes of formation crude at high rates into the producing zone. Although several of the treatments individually have yielded no additional oil, well stimulation by these methods on an over-all basis has been highly successful and should find applicability to other California oil fields producing from similar low-permeability, shaly measures. Introduction The well stimulation treatments discussed in this paper were performed from 1953 to the present in the Brea-Olinda and Esperanza fields, which lie along the Whittier fault trend in the Los Angeles basin (Fig. 1). Since production stimulation by hydraulic fracturing is at present relatively unproved in California, the following geological and reservoir information regarding the producing measures where these treatments were performed is presented to aid in future applications to other California fields. The Brea-Olinda field, where most of the treatments discussed herein (80 per cent) were performed, extends for about six miles laterally along the Whittier fault trend and comprises a practically continuous, elongated belt of accumulation, about 1/2 to one-mile wide. Since the turn of the century, the field has undergone sporadic development as a result of the discoveries of deeper pools and the lateral extensions of existing pools. Cumulative production from the field is 260 million bbl of oil, with some 650 active wells currently producing 17,500 B/D. The Esperanza field, where the remainder of the treatments were performed, was discovered only recently (1956) and has yielded 250,000 bbl of oil, with seven active wells currently producing 400 B/D.