Enhanced Oil Recovery with Horizontal Waterflooding, Osage County, Oklahoma

Abstract

This paper provides details of a project to test horizontal waterflooding as a means of improved oil recovery in Osage County, OK. Supported by a grant from the Department of Energy (DOE), an independent operator, Grand Resources, Inc., has developed a process for selecting and developing candidate reservoirs for horizontal waterflooding. Reservoir screening is the first step in the process and then rock mechanics are used to predict wellbore stability for determining the most efficient completion method. Geologic and reservoir parameters are considered when selecting the radius of curvature for the horizontal well to be drilled and the air/foam drilling fluids to be utilized to avoid formation damage. The final step is to run a comprehensive set of logs through the curve and out into the reservoir allowing for petrophysical evaluation. To accomplish an economically successful project, given the basic assumption of an existing field infrastructure having an adequate water supply well available, the following three goals must be met:demonstrate that horizontal waterflooding is technically and economically feasible for recovering additional oil in shallow low permeability reservoirs;demonstrate that open hole completions are a viable technique based on wellbore stability considerations;demonstrate that short radius rotary steerable technology can drill horizontal wells at low cost and without reservoir damage. Introduction It is solidly established that significant amounts of oil are still trapped in the producing formations when wells in waterflooded fields are abandoned due to high water-oil ratio (WOR) causing production to be uneconomical. Many techniques have been developed with a goal of economically recovering this bypassed oil. This paper discusses the technique of using parallel horizontal water injection and production wells as a method of enhanced oil recovery. Background Historical Waterflooding in Osage County The Bartlesville reservoir in northeastern Oklahoma has been one of the most prolific oil producing formations in the United States. Ye1 reports that 1.5 billion barrels of oil have been produced from the Bartlesville formation through the 1960s. The Bartlesville formation remains an important producing horizon even though it is considered to be in a mature stage of depletion. In spite of the large cumulative production from the Bartlesville, the recovery efficiency has been low, usually less than 20% of the original oil in place(OOIP). Recovery during primary production operations is low due to:a solution gas-drive mechanism, which results in rapid pressure depletion andlow initial reservoir pressure which is a consequence of the shallow depth. The remaining 80% of the OOIP has attracted many secondary and tertiary recovery techniques to be attempted. Secondary recovery operations are often not effective or economic due to shallow depth, existence of natural fractures and low permeability. The Bartlesville sandstone across Osage County ranges in depth from 1,000' to 3,000' is known to be naturally fractured2 and typically has permeability values less than 50 millidarcies (md). In an attempt to improve the economics of Bartlesville waterfloods, operators frequently inject water above the fracture-parting pressure to achieve better injectivity. The result is often unfavorable since the water tends to channel through the fractures bypassing much of the remaining oil in the matrix. Development of small patterns with closer well spacing can lead to improved recovery, however, the economics are impacted negatively because of the number of wells required.

Increased Production Results from Pilot Horizontal Waterflood in Osage County, Oklahoma

“…This paper is an update of SPE 89373 "Enhanced Oil Recovery with Horizontal Waterflooding, Osage County, Oklahoma" by Westermark, et al 1 , published in 2004, which discussed a DOE supported field test using parallel horizontal water injection and production wells to improve oil recovery. Horizontal waterflooding, and specifically horizontal injection wells, have been the subject of numerous studies and technical papers in recent years.…”

Combined Water Dumpflood with Water Injection into Oil Reservoir

“…Westermark et al [8] conducted a project to test parallel horizontal waterflooding aiming to improve oil recovery in shallow low permeability sandstone in north-eastern Oklahoma. The formation is now in the stage of depletion due to solution-gas drive and low initial reservoir pressure.…”