| Abstract |
Djibouti have decided to move ahead into the development program of geothermal energy. Several projects are progressing in different geothermal field, such as Fiale deep drilling project, Galla La Koma shallow drilling project, Hanle exploration wells, as well as Pk20-Ambado exploration wells. Besides these, a particular project concerning the re-entry of Asal offset wells is settled to evaluate whether these wells can produce, or re use for sidetrack, or as a injection wells. In this regard, asset project evaluation & completion engineering studies has been conducted to define conditions and techniques of re-opening these 40 years wells. Asal offset Wells were drilled between 1972 to 1988 during the first geothermal exploration project. Some of these wells were tested but didn’t produce due to sever scaling deposition on the wellbore. Various recompletion methods were researched, examined and analyzed for potential use at the Asal field. To recomplete these wells, they required to review all available options used in the oil, gas and geothermal industry today as well as experimental methods. While casing designs were analyzed to determine the potential options and costs for recompletion methods. Risks associated with each recompletion method were weighed heavily against costs and the availability of equipment. These options were viewed in light of the rig that ODDEG has and plans to utilize in this operation. This rig has a drilling limit of 800 meters, this limit is for drilling to that depth, when recompleting the wells drilling may not have to occur in the operation therefore this limit should not be problem, however if the operation called for running in and set packer, bridge plugs or cement plugs we believe that the rig should be able to run to a depth of 1000 meters. Based on the list of recompletion methods, a recompletion program was developed for each method that had higher probabilities of success. We applied each of these methods to the ASAL wells. The programs that are included in this report are all written for the Asal 1 well. Each of these procedures can then be applied to each of the ASAL wells as the existing completion programs is very similar, only minor changes in depths and sizes would need to be incorporated to make each method case or well specific. These programs represent a step by step procedure to recomplete each well at a zone of interest. The procedures would need to be better defined once the exact recompletion method is chosen and operations are to proceed ahead. These plans contained procedures for abandoning the bottom hole and then a procedure to recomplete the well in a new zone. After each of these procedures were developed, a relative cost estimate was prepared for each of the options. These costs were estimated using U.S. rig and equipment pricing as international reference. We feel that the U.S. price could then be factored up a certain percentage (20% to 30%) to insure that the figures will be useful for Djibouti. Finally, all potential risks and issues that may arise during recompletion were analyzed. The major risks involved in each recompletion method are mentioned in the recompletion programs as well as in the “Potential Risks and Issues†section of this report. The conclusion is the final section of this report. These represent the opinions of our personnel based on experience, document review and research performed. |