DRILLING/WELL COMPLETION

New strategy for sidetrack drilling of marginal wells offshore

Faster, more cost-effective approach produces big savings on small reserve targets

Michael H. Weatherl, Consultant (formerly Chevron USA Production Company), Houston; Jack Hardy, International Snubbing Services, Inc.

During the summer of 1998, many efforts were under way to improve business results for operators in the U. S. Gulf of Mexico. In particular, Chevron’s Gulf of Mexico Shelf Business Unit sought a faster and more cost-effective method of sidetracking wells from offshore platforms.

The operator recognized that there were hundreds of sidetrack candidates adjacent to existing platforms that were marginal or uneconomic using conventional methods. Many of these "marginal" prospects had been known for years, but they had always been uneconomical; i.e., when oil and gas prices go up, rig rates go up, and the wells are marginal; when oil prices go down, rig rates go down, and again, the wells are not economically attractive. It became apparent that if a faster and more cost-effective sidetrack approach could be developed for these types of wells, the upside could be tens of millions of barrels.

As described in the following article, a project strategy was developed using decision analysis and organizational learning principles. The project eventually became known as the "DESSERT" Project, for "development of small reserve targets." Results included a new rig concept, sidetrack drilling operations in three different fields and significant cost savings.