Extended-Reach Drilling Offshore California
Authors: Denney Dennis 
Published: February 2015

This article, written by Technology Editor Dennis Denney, contains highlights of paper SPE 112536, "Extended- Reach Drilling Offshore California: An Operator's Experience With Drilling a Record Extended-Reach Well," by Michael W. Walker, SPE, ExxonMobil Development Company, prepared for the 2008 IADC/SPE Drilling Conference, Orlando, Florida, 4- March. The paper has not been peer reviewed.
The Spanish Bay well was drilled from a production platform offshore California in 1,075 ft of water. This extended-reach well overcame many technical and operational challenges and reached a total depth of 33,435 ft measured depth (MD) [7,663 ft true vertical depth (TVD)] with a 29,720-ft displacement. The challenges overcome included limited hydraulics, high torque, pipe-racking constraints, mud-handling capacity, offshore logistics, and platform-space limitations.

Introduction
The design and execution of extended-reach-drilling (ERD) wells require significant detailed analysis and thorough understanding of rig operating capabilities. Some selected upgrades were required to drill the Spanish Bay well, but mostly, existing equipment was used. Offshore logistics and space limitations on the producing platform were factors in the effort to achieve the objectives of this ERD well. The techniques used to drill this well can be used on future wells, thereby extending the life of existing drilling packages, minimizing capital investments, producing from previously out-of-reach areas, and improving overall project economics.

Field and Area Overview
The Santa Ynez Unit (SYU) is approximately 20 miles west of Santa Barbara, California. Operations comprise an oil and gas processing plant in Las Flores Canyon and three offshore platforms in federal waters in the Santa Barbara channel. The three production plat-forms (Hondo, Harmony, and Heritage) range from 5 to 9 miles offshore in water depths of 842, 1,200, and 1,075 ft, respectively. Each platform has a company-owned drilling package installed. Oil and gas production is transported through subsea pipelines to the processing plant. These fields produce low-gravity (12 to 20°API) sour crude, primarily from the highly fractured chert reservoir in the Monterey formation.
The western Sacate structure was discovered in 1970, and it has remained undeveloped given the inability to access the unit from the Heritage platform. Development of the eastern part of the Sacate structure began in 1999, and subsequent wells have stretched the extended-reach capabilities of the Heritage platform. The Spanish Bay well is an extension of this work and represents an integration of multiple team contributions over a multiyear period, from concept to execution. Detailed drilling planning was crucial to the well's success, from identifying necessary drilling-rig upgrades to working within the production-platform space and capacity constraints.
The Heritage platform and drilling package were installed in 1993. Because the area is seismically active, the entire facility is designed to withstand earth-quake loading. Because the Heritage drilling rig originally was designed with limited ERD capabilities, the drilling pack-age required upgrades as wells became more challenging. Upgrades included a 5½-in. drillstring with wedge-thread connections that could withstand high-torque loads and higher-circulation rates as well as the addition of a third mud pump.