A novel approach for better cementing in horizontal wells

摘要

The incomplete removal of drilling fluids from the annulus of a well prior to the placement of cement can easily jeopardize the likelihood of achieving satisfactory zonal isolation.The removal of drilling fluids is especially complicated in long horizontal wells where typical techniques that improve mud removal such as casing centralization and spacer fluids are met with technical and economic limitations,especially in North America land unconventional markets.Our industry has recently been exposed to a new technology that is specifically designed to be deployed where drilling fluids are likely to be left in the annulus and transient zonal isolation is still required.A new cement formulation,an interactive cement system,was developed to improve zonal isolation in the case of poor mud removal.In many cases,the placement of the interactive cement system resulted in wells with improved bond logs compared to neighboring wells.Considering the primary function of the interactive cement system was to improve zonal isolation,a battery of laboratory-based experiments are described to develop insight into the bond log Improvement mechanism.In our laboratory tests,we reproduced the field-based acoustic observations of large mud channels in proximity to the interactive cement system,and we propose a simple mechanism relating the interactive cement’s expansion to the improvement in shear bonding in narrow mud channels.