Gas Field Developmental Strategy from Exploration Well Test Data

Abstract

This paper was prepared for the Second Annual European Meeting of the Society of Petroleum Engineers of AIME, to be held in London, England, April 2–3, 1973. 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 Field development strategy in areas of high development cost and operating expenses can have a considerable impact on the economic potential of a new field discovery. The degree to which development strategy may be optimized depends on availability of data with which to define the reservoir. The Hewett gas field, located approximately 20 miles offshore northeast of Bacton, England, was discovered in October, 1966. Geophysical data and subsequent exploration drilling resulted in gross definition of the reservoir and eventual formation of a field unit. Core and log analysis data from three exploratory wells and pressure buildup test data obtained by a sensitive pressure gauge were used to define reservoir characteristics. All applicable data was used in a mathematical reservoir s simulator to prepare sensitivity analyses for determining a feasible development program. A scaled mathematical model representing program. A scaled mathematical model representing two dimensional gas flow was used as the basis for the work. The model was designed primarily to study the effect of tubing size on well deliverability and to determine the effects of well interference incurred in various field development programs. programs. Results of several sensitivity runs indicated that, in high permeability reservoirs such as Hewett, wells may be clustered to minimize platform costs and operating expense. Pressure platform costs and operating expense. Pressure loss in the tubing due to friction appeared to be the predominant loss in the system. At the high rates which the wells are capable of producing, tubing size should be as large as producing, tubing size should be as large as operationally and economically feasible. Actual field development to date is compared with early recommendations which resulted from the studies. Introduction The Hewett gas field was discovered in October, 1966, with the drilling of exploratory well 48/29-1 by the ARPET Group, of which ARCO Oil Producing, Inc. is the operator. The field is located approximately 20 miles offshore northeast of Bacton, England, in approximately 125 feet of water (see Figure 1). Available seismic control at that time indicated that the field extended through ARPET blocks 48/28, 48/29 and Phillips block 52/5 as a narrow, elongated structure trending northwest-southeast and bounded by varying amounts of faulting on each of the two sides.