Publications

It has long been postulated that placing acid into a well through coiled tubing provides for better stimulation treatments than those achieved by simply bullheading. Commonsense suggests that having the stimulation fluid enter the well via a dedicated conduit, adjacent to all points along the length of a treatment interval, will produce more uniform stimulation of that interval. However, the opposing argument is that, irrespective of the delivery method, all fluid follows the path of least resistance and will, therefore, flow into the areas of highest permeability, the ones generally least in need of stimulation. Diversion techniques, employed to improve treatment distribution, can often be applied to regular bullhead treatments as easily or even more easily than they can with coiled tubing. This is not necessarily so when pumping stimulation fluids through SSDs (Sliding Side Door) or through the ESP (Electric Submersible Pump) itself.Controlled tests to compare bullheaded and coiled tubing delivered treatments are difficult, as no two wells are identical. This paper evaluates 19 wells to provide statistical evidence of which delivery system does generally provide for the best end results. The paper suggests what the underlying reasons for the spread of results might be and suggests criteria as to when coil is, and is not, the best probable choice. It also discusses innovative methods to improve treatment distribution in wells, thereby maximizing stimulation efficiency.