A Cost Effective and User Friendly Approach to Design Wireline Formation Tests

Mini-DSTs are gaining more and more popularity as a possible alternative to conventional well testing especially where there are major environmental and economical constraints. The increased offshore exploration activity, which often implies highly risky and huge operational costs, makes the conventional well testing less attractive in favor of other technologies that can provide some of the key dynamic information about the well-reservoir system through relatively quick and less expensive operations. The design phase is recognized to be one of the most critical aspects in order to guarantee an acceptable value of information in exploration scenarios where very limited data is available. The success of any mini-DST operation can be significantly compromised if two major issues are not addressed in the design phase: possibility to clearly identify the radial flow behaviour, and avoidance of noise in the pressure response due to the gauge resolution. The paper describes a new user-friendly approach for mini-DST design so as to easily identify whether this technology can be successfully applied. The charts allow avoidance of the use of dedicated software, implying additional costs and requiring trained personnel. The approach is based on the use of dimensionless and dimensional charts, which are of general validity because they can be applied to any lithological environment and for any type of hydrocarbon. Field applications proved the charts to be very powerful because they could predict the range of effectiveness of mini-DST‟s.