Drilling And Producing Marginal Prospects From A Jack-Up Drilling Rig
Authors: Phenix H.V. , Mannon R.W. , Vicars R.A. 
Published: December 2007

In an effort to proceed with the development of marginal offshore projects, various types of temporary producing systems are coming into view. A technique producing systems are coming into view. A technique is presented to evaluate the feasibility of utilizing a jack-up rig as a temporary producing platform. Jack-ups certified to perform under a given set of conditions for the relatively short period required in well drilling might experience failure when subjected to the same conditions of a longer duration period of production. Aspects that become critical period of production. Aspects that become critical during extended periods of service are examined and analyzed. In addition to evaluating rig performance, the method also provides the basis for an economic comparison of the available jack-up rigs.

Introduction

The abrupt changes in economic parameters in the last five years together with the rapid growth in offshore technology have given rise to some interesting departures from conventional drilling and producing methods. Various types of temporary or producing methods. Various types of temporary or early production schemes are being developed. These new schemes provide such often needed economic features as opportunities for cash flow acceleration, reduced front-end cost and greater adaptability for short life projects. A project under evaluation in the Mediterranean by a group of companies fits the general mold. It is in 300 feet of water, has minimum reserves and carries a high risk of production short fall due to the character of the reservoir. Accordingly, the Operator of the project decided to investigate the possibilities of utilizing a jack-up as a temporary production facility. A search of rig availability turned up a number of jack-ups of adequate size and water depth capability for the project, however, there was a question as to performance during an extended production period. Jack-ups certified to perform under a given set of conditions for the relatively short period required in well drilling might experience failure when subjected to the same conditions over a longer duration production phase. Accordingly, the Operator asked an independent engineering firm, experienced in this area, to make the evaluation.

In the study request the Operator asked the firm to address itself to the following requests.Examine the technical feasibility of using one of several jack-up rigs available for longterm wells.Provide a basis for the Operator to make an intelligent choice of the best rig to employ from the standpoint of economics for use as a temporary producing platform.Develop the necessary auxiliary subsystems to be used in conjunction with the rig itself.Recommend a technique for positioning the jack-up over two existing sub-sea wells and the technique for tying the wells back to the floor of the jack-up.Make provisions for drilling two additional wells during the production period, if required.

CONCEPT

The concept considered by this paper is based on the use of a jack-up rig serving as a drilling/production platform. The rig is to be placed on location platform. The rig is to be placed on location at two closely spaced existing wells, elevated, a well-guard will be set and two new wells will be drilled adjacent to the existing wells. The existing wells and the new wells are to be extended to the surface through conductors supported by a well-guard structure. Crude flowing from the wells will be treated in a production subsystem mounted on the deck and then will flow down a well-guard supported flow line to a pipeline or floating storage subsystem.