Analyzing a Multi-Lateral Well Failure in the East Wilmington Field of California

Abstract

Introduction As the industry pursues optimum cost drilling techniques, more focus is being applied to multi-lateral technology. The presently available literature invariably focuses on the cost and efficiency benefits of drilling multi-lateral wells. What is missing in the media, however, are the benefits associated with publication of the negative aspects or costly failures of higher-technology multiple-lateral projects that require a mechanical tie-back or pressure seal at the junction of the laterals (i.e. Class 3 or 4 type multi-lateral wells, respectively). This paper is a case study of a Class 4 multilateral well attempted by Thums Long Beach Company in the East Wilmington Field of California. To date, this case study represents the only detailed analysis of an unsuccessful attempt to drill a Class 4 multi-lateral well. Starting with a field and well profile, this case study explores Well B743A in the Long Beach Unit of the East Wilmington Field of California. The discussion progresses from the original proposal through the drilling and completion of the lower lateral to the drilling of the upper lateral, and then to the plugging and abandonment both laterals. Finally, the analysis provides an examination of six critical problem areas encountered during the drilling of Well B743A: hole cleaning, cementing and junction stability, whipstock orientation, tubular size, re-entry, and risk management. These are areas that are problematic for most operators and contractors struggling with multi-lateral technology, especially the drilling of Class 3 or Class 4 multi-lateral wells. Field and Well Profile The Long Beach Unit of the East Wilmington Oil Field is located just offshore at the southwestern extension of the Los Angeles Basin of California (Fig. 1). The field produces from three major zones, the Ranger, Terminal, and Union Pacific-Ford zones (Fig. 2). Individual sand units are continuous and can be correlated over the Long Beach Unit and beyond. The structural setting is an asymmetrical northwest to southeasterly trending, faulted anticline. P. 169^