Drilling rig design for a unique oil field application – field redevelopment in Ruehlermoor “peat mining field”

Research output: ResearchMaster's Thesis

Authors

Abstract

A major part of the German oil and gas consumption is covered by imports, thus it is important that Germany strengthen the domestic production. The oil field "Ruehlermoor" with more than 500 existing wells is Germany's largest onshore oil field and is operated by a joint venture of GDF Suez and ExxonMobil. It was discovered in 1941, is located in a peat mining area at the German-Dutch border and covers 24 square kilometers. Its infrastructure is unique in the world. Due to the unstable underground in the field most transports are done with a narrow-gauge railway (track width 900 mm). The peat mining industry and the oil production operate simultaneously. Parallel arranged dykes, which are several meters high and up to 40 m wide serve as area for the sucker rod pumps, the infrastructure and for drilling and workover operations. The oil field is in production for 60 years and has an exploitation of 27 % (2015). Since the 80s, the reservoir is stimulated with hot steam injections. Meanwhile, the pipelines of the field and the steam generation plant have to be replaced. The redevelopment of the field needs over 100 new wells in 500 - 700 m depth in the next 5 years, the construction of a cogeneration plant and the consequent increase in steam injection and oil production has to ensure the economic viability of the field. The last wells in the Ruehlermoor oil field were drilled with a company's own carrier rig built in 1982, which could compensate the small space conditions by its compact design, but is not capable to drill such a drilling campaign. The future drilling rig needs a hook load of 150 tons except load to pull casings according to the thermal effects in tension. It must be able to transport by rail and the individual parts must not exceed 60 tons. There is no ability to skid in Ruehlermoor, because the surface locations of the new wells are located in between of the existing wells. The small size of the well site and the narrow dikes on which only a road and one rail are available as infrastructure, transport and the rig up/rig down procedure is a major challenge. The rig must be able to drill a minimum of wells, before the cogeneration plant goes into production in 2020, in order to ensure efficient operation of the project. The acquisition of a new rig is therefore essential. Through a Europe-wide tendering process 11 drilling contractors were invited to propose their rig concepts and 4 of them submitted tender documents. This thesis accompanied the tendering process, deals with the peculiarities of the oil field Ruehlermoor and shows why the construction of a new rig is needed to meet the circumstances of the field and why the transport of the rig has a decisive impact on the success of the project. Furthermore, the thesis describes the concepts of the contractors and evaluates them technically. For this, matrices have been developed with differently weighted evaluation criteria in accordance to the circumstances, which are needed to do an efficiency analysis. A recommendation for the best concept is then developed using the analysis.

Details

Original languageEnglish
Supervisors/Advisors
Award date18 Dec 2015
StatePublished - 2015