Handling High Pressure Cycling Projects at Northwest Branch, Louisiana

Abstract

Abstract Unusually high surface injection pressures ranging from 6,500 to 6,700 psi have been required in pressure maintenance operations at Northwest Branch, Acadia Parish, La. The high injection pressures were necessary to permit cycling operations at near dew-point conditions in the condensate-bearing Nodosaria Blanpiedi No. 1 sand. Injection volumes at this high pressure have averaged 12 MMcf/D since injection started in Sept., 1955. The cycling phase of operation is approximately 65 per cent complete prior to blowdown operations. Reservoir and fluid characteristics are described and production history is presented. Performance of the cycling phase of operation is presented and is based on the original 2,100-psi separator condensate in place at start of cycling operations. Compressor operating problems are also presented. Introduction The Northwest Branch field, Acadia Parish, La. was discovered in Dec., 1951, and was unitized for pressure maintenance (cycling) operations on June 1, 1955. The Unit consists of the Nonion Struma No. 1 sand and the Nodosaria Blanpiedi No. 1 sand; cross faulting further defines the Unit area as Block A and Block B. Cycling operations to date include the Nodosaria Blanpiedi No. 1 sand in Block A and the Nonion Struma No. 1 in Block B. Herein is reviewed the cycling operations in the Nodosaria Blanpiedi No. 1 sand in Block A where unusually high (6,500 to 6,700 psi) surface injection pressures have been required. Geology and Reservoir Characteristics The condensate-bearing 11,100-ft Nodosaria Blanpiedi No. 1 sand at Northwest Branch Unit represents a productive reservoir geologically classified as closure by faulting. As illustrated in the structural interpretation (Fig. 1) the productive reservoir is bounded by faults on four sides with a limited aquifer on the structural flank.