3. Development Drilling, Production and Workover 1/ a. Platform Installation and Production Well Drilling Offshore drilling and production operations are usually conducted on fixed, bottom-founded, water surface-piercing platforms (Fig. 43). If exploratory efforts are successful in proving a hydrocarbon reserve, production operations are initiated by installing platforms (Fig. 43) to serve as a base for drilling development wells and for subsequent production operations. A number of wells may be directionally drilled to develop a large area from a single platform. Many platforms in the Gulf today contain as many as 20-30 wells. During the 27-year history of oil operations in the Gulf of Mexico, industry has gained a good understanding of the physical forces acting on offshore platforms. Therefore platform design is a matter of selecting the optimum geometry and sizing structure members with appropriate safety factors to withstand maximum anticipated environmental forces and operational loads. Appropriate design procedures are outlined in API Recommended Practice RP 2A and various API specifications. These guidelines have been prepared to cover engineering design and operation of offshore 1/ Much of the information in this section has been excerpted from Statement of C. C. Taylor, Dept. of Interior Hearing, Louisiana Offshore Annual Sale No. 33, November 28-29, 1973. ་་ (from "The Offshore Search for Oil and Gas, Exxon Background Series No. 2R, Nov., 1972, Public Affairs Dept., Exxon Corp.) structures and related equipment. USGS OCS Order No. 8 defines regulatory approval procedures for platform design and installation. Platforms have been installed in the Gulf of Mexico in water depths to 373 feet, and technology exists to extend platform operations to much greater depths. Platforms are now being fabricated for installation in the North Sea in water depths to 460 feet. A design for installation in 850 feet of water at the Santa Ynez Unit in the Santa Barbara Channel has been completed and is ready for implementation. The primary new requirement for platforms in depths beyond current operations is for procedures to erect the platform at the offshore or floated to the offshore location for erection. During the first stage of erection, the lower portion of the platform, which extends from the ocean floor to just above the water level, is set in a vertical position on the ocean floor. Pilings are then driven through the structure legs to secure the platform to the bottom. In the second stage of erection the platform deck is installed on the supporting structure. Large platforms in deep water will require use of more and/or larger lifting, transportation, and installation equipment than shallow water platforms. However, once set and secured with pilings, subsequent platform operations are identical to those that have been proven safe in current operation. No technological limitation in platform installations in water depths to at least 1000-1200 feet are apparent at this time; thus, essentially all of the tracts proposed for lease in the March, 1974 sale should be able to be developed in the conventional manner. Unlike Buoyant towers have potential applications in water depths greater than about 1000 feet. These towers are pivoted at the base and are stabilized in a vertical position by buoyant chambers. conventional platforms, buoyant towers sway under the action of wave forces instead of resisting them. In waters much less than 1000 feet deep, however, the sway of these towers would be excessive. Towers that would support two drilling rigs, production equipment, and 40 to 60 wells appear feasible for water depths between 1000 and 2000 feet. One concept of such a tower is shown in Fig. 44. The drilling rig, power plants, generators, living quarters, storage sheds and other components, constructed in modular form, are added to the platform, and production well drilling commences. Equipment anticipated for use on deep water platforms is similar to that being used safely in current shallow water operations, and will be installed and operated in accordance with safe practices accumulated from industry experience. practices form the basis of USGS OCS Order No. 8, which gives the safe practices a regulatory mandate. This order specifies multiple, redundant controls and safety devices including safety These |