"Pay now,or pay later"fits in many industries and circumstances.In well construction,ideally the operator wishes to be in a position to decide which of these alternatives is the most economic.Engineered solutions,designed to improve wellbore strength and reduce drilling non-productive time due to lost circulation,are directed at managing wellbore stresses(WSM).This fully engineered approach should include means to help prevent lost circulation as well as stop losses.Prevention of lost circulation by improving the wellbore strength is accomplished by designing and applying borehole stress treatments that increase the hoop stress around the wellbore.The technology development within the industry that led to the applications of these concepts will be discussed.Proprietary hydraulic design software(HDS)can predict the equivalent circulating density(ECD)over an interval in one module,calculate the width of a fracture that may be initiated,and select and design a proper material and particle size distribution that can efficiently prop and plug that fracture in a second module.A third module then predicts the change in rheology resulting from the addition of the specialized lost circulation materials,which then is cycled full circle back to update the ECD calculations.Contingency chemical sealant(CS)treatment applications are systems designed to react with the drilling fluid itself to create highly viscous and cohesive sealants in the wellbore that are displaced into the lost circulation fractures.Drilling-fluid-reactive systems are not dependent on temperature or pressure,thus removing a significant amount of placement uncertainty present with cross-linked systems.This combination of planning and application tools allows the operator to make decisions ahead of time during the"drilling the well on paper"phase as to which approach is the most economic - prevention(pay now)or remediation(pay later).
展开▼
