Joint Research/Operations Programs Accelerate Massive Hydraulic Fracturing Technology
Authors: Veatch Ralph W. , Crowell Ronald F. 
Published: December 2007

To develop the significant resource potential available from tight formation gas (TFG) reservoirs requires special stimulation techniques such as massive hydraulic fracturing (MHF). The high cost of MHF treatments and the need to create deeply penetrating conductive fractures require a high level of technology. Amoco Production Co. initiated a joint effort between the Research and Operations Depts. to address the wide variety of complex design requirements. Specific programs were established to investigate fracture height, fracture pressure behavior (including post-treatment pressure decline), in-situ stresses and rock properties, and fracture azimuth. They were developed by research personnel in cooperation with engineering staff associated with TFG plays. The broad geographical nature of the programs required management involvement at several organizational levels throughout the company. The effort was extremely successful in accelerating MHF design technology and providing more reliable design data. Data generated have been usedto increase conductive fracture length significantly per unit volume of fracturing fluid andto reduce unwanted vertical fracture growth in several TFG plays.

In addition to improving design technology, the programs have been highly beneficial in accelerating technology transfer between research and operations personnel. This paper presents an overview of the total effort and discusses the results obtained from each of the specific programs.

Introduction

Low-permeability gas formations offer a significant potential to enlarge our recoverable gas resources. Current stated figures claim additions on the order of 190 to 570 Tcf in total U.S. recoverable reserves. In perspective, one might compare this with the 180 to 200 Tcf of currently booked reserves from conventional gas reservoirs. Producing rates of 4 to 8 Tcf/yr from tight formations are estimated for the 1990's. However, this is possible only with application of special stimulation techniques such as MHF. These treatments, which currently range in size from 100.000 to 1 million gal of fluid and up to more than 3 million Ibm of proppant, can impact total development costs significantly. Fig. 1 displays typical costs of MHF treatments relative to total drilling and completion costs (including MHF) in four TFG areas where our company is currently active. It shows that MHF costs can account for a major portion of the total well cost. Hence, it is imperative that our fracture treatment design technology be sufficient to optimize TFG development economics. As the industry entered the era of MHF during the 1970's after some 30 years, of fracturing experience and research, our abilities to determine fracture dimensions (lengths, L, widths, b. and heights, hf), shapes, symmetries, and azimuths of the large fractures resulting from MHF treatments were not highly developed. Consequently, our abilities to optimize treatment designs economically were sometimes deficient. As we expanded MHF activity into additional TFG areas, the need to address these deficiencies became increasingly more pronounced. In an attempt to enhance the development of our TFG activities, we embarked on a joint research/operations effort to improve MHF design technology. The effort was formulated to accelerate teaming in the areas of both theory and application and to integrate theory and practice as rapidly as possible. It entailed a cooperative, coordinated effort between the Research and Operations Depts. and involved field, engineering, management, and research personnel at all organizational levels.

JPT

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