Advanced Real-Time Analytics Allow Performing the Shallowest InjectionTest Ever on the Norwegian Continental Shelf NCS - Rational,Planning,Execution and Results

摘要

Reservoirs in the Barents Sea are several times shallower than in other parts of the NCS,essentially due torecent uplift and erosion of younger sediments.A proper understanding of their geomechanics is consideredparamount for their successful development.In turn,the lack of any available analogue makes the properin situ measurement of key parameters compulsory.The paper describes the planning and execution of an appraisal well solely dedicated to the purpose ofgeomechanics data acquisition in the shallowest oil reservoir on the NCS - i.e.coring,logging,XLOTand injection testing.It focuses on the operations conducted in the oil reservoir itself,which included anentirely novel multi-cycle injection test aimed at estimating the large-scale thermal stress coefficient of theformations around the well - i.e.the impact of the injection temperature on the fracture pressure of theformations.Every operation in the well was challenging due to the sea depth being about twice that of theoverburden thickness and to the formations being quite consolidated,which was met by careful iterativemultidisciplinary-planning.The equipment was often taken to its limit and sometimes extended beyond itsstandard use - e.g.the metering systems.The injection test itself could not be performed traditionally - i.e.use of surface data and downholememory gauge.Instead,the downhole gauge data were sampled,pumped out and transferred to a remote sitewhere real time advanced analytics was used to ensure that safety criteria were always met throughout theoperation in terms of vertical fracture propagation and lack of reservoir compartmentalisation.In addition,this allowed adjusting the planned injection schedule to the exact formation's response,which could not befully quantified ahead of time.All the targets of the appraisal well were met.The injection test - i.e.the shallowest on the NCS andperhaps worldwide in an offshore environment - was performed successfully.Its main results are consideredessential for a possible future field development - e.g.the injectivity is confirmed and,in addition,asignificant thermal effect is proven.The series of novel technologies deployed in the extreme environment presented in the paper can easilyand beneficially be extended to more traditional reservoirs.This concerns performing multi-cycle injectiontests on appraisal wells on a systematic basis to prepare and optimise the development plan,real-timemonitoring through advanced analytics and adjustment of these tests,start-up of injection wells during fielddevelopment,monitoring and optimisation of water injection schemes,etc.