This paper was prepared for the 40th Annual California Regional Meeting of the Society of Petroleum Engineers of AIME, to be held in San Francisco, Calif., Nov. 6–7, 1969. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract Hydraulic fracturing has been tried in an effort to stimulate production from a massive diatomaceous earth formation in Lost Hills Field, California. The technique, itself, was very conventional, but the application was unusual in that this formation is much softer than those in which fracturing is routinely used. Preliminary to field application, laboratory tests were conducted on formation cores to investigate the problems of proppant embedment and fracture flow capacity under simulated overburden loads. The results of these tests indicated that production stimulation should result from fractures packed with complete layers of 10–20 mesh proppants. The treatment design sought to circumvent the possibility of proppant embedment and consequent fracture closure by means of packed fractures. Through selective burrless perforating and a continuous eight-stage treatment perforating and a continuous eight-stage treatment utilizing sealer balls, the entire 750-ft interval was treated. The use of radioactive sand throughout the job, together with gamma logs before and after treatment, aided in evaluating the success of the operations. A comparison of the radioactivity logs and recovery of the sealer balls clearly showed all the perforated intervals had been treated as planned. Vertical fractures were indicated. planned. Vertical fractures were indicated. In some cases, where intervals were not separated by sufficient vertical distance or by zones of significant porosity change, fractures initiated at different sets of performations appeared to join. Early post-treatment productivity was somewhat better than that of offset wells. However, the production rate declined rapidly and after two months was essentially the same as the offset wells. The treatment was not economically successful. Introduction Volumetric calculations indicate that several hundred million barrels of oil are in place under Gulf properties in Lost Hills Field, place under Gulf properties in Lost Hills Field, Kern County, California.

The introduction of new fracture propping agents that are. brittle but much stronger thun sand creazed the problem o! what loading strength is required for a propping agent to be efiective in a given jormation. It is shown that the load at which the propping agent crushes shouid exceed the ioad at which total embedment in the jracture fuces is possibie. Simpie labor~rory tests to determine loading strength of the propping agent and embedment in the fracture faces, and use of these data in seiecting a prop-ping agent for a given formation, are discussed.

Published correlations for the principal aspects of hydraulic fracturing were combined into a digital computer program to facilitate the study of interrelated variables. The computer program includes individual relationships for fracture width during pumping, fracture area generated, propping agent embedment, flow capacities of propped fractures and transport of propping agents in horizontal fractures. The effects of more than 20 treatment and formation parameters on the predicted results of hydraulic fracturing treatments were studied. The effects of these parameters were determined for (1) fracture width during injection, (2) fracture width after the overburden comes to rest on the propping agents, assumed not to be crushed, (3) generated and propped fracture area, (4) location and concentration of propping agents in the fracture when injection ceases, (5) flow capacities of the various propped sections of the fracture and (6) expected increase in the well productivity. The effects of propping agent, formation and fracturing fluid parameters on well productivity are discussed. The parameters that were found to have the most pronounced effects on hydraulic fracturing treatments are injection rate, treatment volume, fracturing fluid coefficient, size and amount of propping agent, spearhead volume, well drainage radius and formation capacity.