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Horizontal Well Technology Applications for Improved Reservoir Depletion, Kern River Oil Field

Shotts, Noel J.; McNaboe, Gerald J.

Estimated to have over 3.5 billion barrels of original oil in place, the 114 year old Kern River Oil Field was a sleeping giant until the late 1960's when steamflooding began and oil production ramped up from 19,000 to over 142,000 BOPD by the mid 1980's. In 2007 the cumulative production reached two billion barrels of heavy oil. With the introduction of horizontal wells in 2007 the production decline curve that had been at approximately 6% began to flatten and today the decline rate is at 1 to 2%. Current production from the field is about 70,000 BOPD. Since the discovery of the field, over 20,000 wells have been drilled with the largest producers, horizontal wells, drilled in the last 6 years.

The reservoir consists of amalgamated braided stream channels with the top of the reservoir encountered 50 to 1000 feet below the surface. Porosities range between 29-33% and permeability is 1-8 Darcies. Nine producing zones are recognized in the stratigraphic column with additional stratigraphic complexity introduced by the braided stream depositional setting. Average oil gravity is 13 degree API and average viscosity is 4,000 centipoise at initial reservoir temperature.

The primary tool utilized for development of the field is 3-D earth modeling to integrate the large volume of well data with reservoir temperature and saturation over time. The full field 3-D reservoir model (FFM) was built using over 12,000 open hole logs for lithologic data and incorporating the most recent saturation information from C/O logs, resulting in a 155 million cell model resolved into 50 ft x 50 ft x 2 ft cells.

An example of recent application of the surveillance data and FFM to improve oil recovery is demonstrated in the drilling of horizontal wells into heated areas of the reservoir. Wells are targeted where the oil recovery predicted by decline curve analysis is substantially less than the volumetrically calculated recovery using the FFM. Since 2007, over 400 horizontal wells have been drilled to improve recovery of remaining oil, adding over 17,000 BOPD of new production. The wells target zones below 400 feet TVD and typically have laterals of approximately 1600 feet. Initial production rates from the horizontal producers are several times greater than offset vertical producers. Substantial additional development opportunities also exist for application of shallow horizontal drilling, which is an area of current technology focus for the development team.

 

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013