A Case Study of Value Generation with Intelligent Well Technology in a High Productivity, Thin Oil Rim Reservoir

Abstract

Abstract The Application of Intelligent (or Smart) Well Completion Technology (IWT) has not progressed as rapidly as originally expected. This is partly due to management's lack of confidence that the "added value" is sufficient to justify the extra investment. This concern can be addressed by publication of well-documented examples of IWT delivering value. This paper describes the detrmination of the "added IWT value" from maximising oil production, within allowable gas constraints, for the Norwegian NH-field that produces from a thin oil-rim using high productivity, horizontal-wells. The well drawdown is similar, or lower, than the frictional pressure drop along the completion length. This generates a skewed production profile along the length of the completion; the bulk of the oil production - and early gas and water break-through - occurring at the heel of the well. This is further accentuated by the presence of a tilted, high-permeability sand that connects the heel of the well to the gas cap. A further complication is that the bubble point is close to the initial reservoir pressure (in fact at the gas-oil-contact, the saturation pressure and the reservoir pressure are identical) and 34% of the total Hydrocarbon Liquid is associated condensate in the gas cap. This paper not only shows how the "added IWT value" was derived, but also the:Development of a well-performance management philosophy,Optimisation of the conventional well using a sector of the full-field model,Insertion of a detailed, Intelligent Well (I-well) completion model within this model, (iv) Development of an I-well design and operation philosophy,Illustration of the advantages, disadvantages and utility for well optimisation of available keywords within commercial simulation packages. Finally, understanding how the I-well Completion "adds value" allows the development of guidelines for the choice of candidate wells in this type of reservoir where IWT is capable of delivering value. Introduction I-well completions employ localized pressure restrictions (Interval Control Valves (ICVs)) to balance the production profile along the length of the well completion by splitting it into two (or more) sections. The aim of I-wells is to optimise the production (maximizing net oil while delaying the gas and water breakthrough)[1]. This can either be done:at a well or multi-well system level in order to maximize the instantaneous oil production by managing the available well production potential if it is greater than the production system capacity, orin a reactive manner (responding to the breakthrough of unwanted water or gas) at the wellbore, orby optimizing the (complex) reservoir/well system through control of the flood fronts between the wells by managing the injection and off-take profile in an active manner. This latter requires sensors that can image fluid fronts between the wells. Alternatively a model capable of predicting the flow of fluids within the well and reservoir with time could be used. A detailed well model incorporated within a reservoir simulation model is the most complete (and complex) option for this. Still, an optimisation methodology is required to maximize the production and take advantage of the flexibility offered by the ICV's.