Drilling operations, have been under way on Exxon's Hondo platform, set in 850' of water in the Santa Barbara Channel, since September, 1977. This paper presents some of the design decisions necessary prior to commencing drilling operations, discusses the drilling progress during the first 18 months, and summarizes the concept and application of a Drilling Task Force study, a technique which has been used successfully on several occasions by Exxon to improve drilling performance. performance.
Exxon's Hondo field is location in the Santa Barbara Channel 5-1/2 miles (9 kilo meters) off of the California coast approximately 25 miles (40 kilometers) west of Santa Barbara, California (See Figure 1). The Hondo platform is location in 850 feet (260 meters) platform is location in 850 feet (260 meters) of water, somewhat north of the productive limits of the reservoir, while the reservoir itself is overlain by water from 1,200 to 1,500 feet (365 to 460 meters) deep. Thus, all development wells drilled will be directional and generally to the south. The Hondo field is a major hydrocarbon accumultion approximately 6 miles long and 1-1/2 miles wide (9.5 × 2.5 kilometers) with an estimated areal extent of 5,500 acres (22 × 10(6) meters) Less than one-half of the reservoir will be developed initially from the first platform, while full development of the reserves will require an additional platform.
The primary reservoir of the Hondo field is the normally pressured, fractured Monterey formation composed of extremely thin beds of shale, dolomite, and several types of chert. The Monterey reservoir is approximately 1,300 feet (395 meters) thick and has formation dips as high as 60 degrees (1 radian) from the horizontal. The Monterey crude oil contains approximately 4% sulfur and ranges in API gravity from the mid 20's to less than 10. The solution gas contains less than 1-1/2% hydrogen sulfide. In addition, there are sandstone reservoirs which lie below the Monterey formation that will be developed as secondary objectives.
After several design iterations, the most economical initial development plan called for a 28-well platform which would reach approximately 40% of the Monterey reserves. The 28 wells would consist of 21 Monterey chert development wells, 3 sandstone development wells which can later be recompleted in the Monterey, 2 water disposal wells to allow injection of produced water, and 2 gas injection wells for injection of the produced gas.
The produced water will be injected into water bearing formations lying above the Monterey reservoir. The gas will be reinjected into the producing reservoir until gas sales are commenced. The Monterey wells will range in measured depth from 10,000 to 13,000 feet (3000 to 3950 meters), while the sandstone penetrations will go as deep as 14,500 feet (4420 meters). The maximum angles of these wells will be about 60 degrees (1 radian) from vertical, with a maximum planned horizontal displacement of 8,900 feet (2700 meters) - somewhat over 1-1/2 miles (2.4 kilometers).
During the initial planning of the drilling program there were several problems that needed to be solved associated with the water depth and reservoir fluid properties.