Drill Cuttings Reinjection for Heidrun: A Study
H.R. Crawford, J.A. Lescarboura · 1993
SPE MembersAbstract. Drilling of 56 wells from the Heidrun Platform in the Norwegian North Sea may generate about 150 million pounds of drill cuttings. If oil-based mud (OBM) is used on any of the wells these oily cuttings will need to be disposed of in an environmentally sound manner. This study was to assess the feasibility of disposing of these oily cuttings by reinjection into a fracture, initiated from a purpose-drilled reinjection well. A slurry was prepared from OBM drill cuttings from the Norwegian North Sea using a commercial cuttings slurrying system. Laboratory and pilot-plant tests of this slurry were conducted to measure: composition, rheology, laminar and turbulent friction loss, and leak-off coefficient. Laboratory tests were performed simulating the flow of the slurry along a fracture in a permeable formation with leak-off occurring from one side of the fracture. The paper describes the results of the tests. It concludes that it is feasible to dispose of the cuttings by reinjection into a fracture created in an impermeable formation. A procedure is suggested. It theorizes that permeable formations can act as barriers to the vertical growth of the fracture.Introduction. With current technology, some high-angle wells can only be drilled safely and economically by use of OBM. But, drilling with OBM results in oil-contaminated drill cuttings.Ever tightening environmental regulations make ft difficult to dispose of these contaminated cuttings economically. In the Norwegian North sea a common method of disposal involves shipping the cuttings to shore for land fill or other methods of disposal. Since loading operations must be suspended when waves are too high, considerable storage space must be available on the drilling platform to allow drilling to continue when off-loading of cuttings is not possible. This extra space severely increases the cost of platforms which are already expensive. Under these conditions, a disposal method that can be used continuously regardless of weather is desirable. Reinjection of the oil contaminated drill cuttings into a suitable formation is such a method.Disposal of cuttings by downhole reinjection is relatively new technology which is just now achieving commercial usage. A number of technical publications have appeared recently in the literature describing this method of cuttings disposal. Although different methods of slurrying the cuttings are involved, all these publications address disposal of the cuttings from one well into the same well, i.e., the disposal of relatively small volume of cuttings into each well. Furthermore, many of these papers imply disposal of the cuttings into permeable