Extreme Well Condition Demands Customized Completion Design for Fracturing and Well Testing in HPHT Exploratory Well

Abstract

Abstract New and extreme challenges, from engineering and operational standpoints, were faced during the preparation and execution of an exploration well in an HPHT environment. COVID-19 pandemic outbreak made it even more challenging leading to several issues in terms of material deliverability and personnel availability. The nature of the reservoir required hydraulic fracturing to be performed prior to test the explorative target. The entire fracturing treatment and well testing were performed through an instrumented well testing string which allowed to save rig time and, thus, costs. This paper goes through the selection of proper completion and hydraulic fracturing technologies to withstand the challenges that such environment poses to deliver the job safely and timely. The completion hardware selected to perform the job was a well test/frac string equipped with sensors, tester valve and circulating valve. A mechanical set down weight non-rotating packer isolated the reservoir from the annulus, a standard completion safety valve and a tubing hanger with X-Mas Tree completed the configuration of the DST string. Another important aspect was the need of heavy brine (i.e. bromide based) which exposed the equipment and material to aggressive environment. Hydraulic fracturing operations were carried out smoothly with the support of a dedicated frac vessel reaching up to 10,000 psi at wellhead and more than 12,000 psi at bottomhole. The total amount of proppant pumped into formation was one of the highest in the Operator experience and good results were achieved in unknown formations. The result of the stimulation job was a good values of proppant concentration in the fracture as long as a good frac width. During well testing operations high drawdown was reached without compromising the integrity of the string. This paper outlines and describes the completion and fracturing job engineering, preparation and execution phases including all the mitigation actions and lessons learned gathered during operations. Moreover, this experience showed how a resilient culture and an integrated approach between subsidiary operations and headquarter technical support, lead to successful operative results.