CITADEL EQUIPMENT: STALWART HD STAGE TOOL
OPERATOR: ROCKCLIFF ENERGY BASIN: EAST TEXAS, USA
CHALLENGE: Prior to completion, 5.500 production casing was found to be leaking in the uncemented vertical. A casing patch was run to cover a leaking connection; however, two additional connections were found to leak at 4000 and 5000 psi, with more leaking connections likely. The entire string above TOC needed to be replaced. A string shot was used to back-off casing at just over 6,000’ with the plan to re-enter with new casing and cement from the previous top of cement to surface. A stage tool was required to access the annulus and pump cement to surface. Not an ordinary stage tool, however, a hydraulic opening, HPHT, fracable, slim-hole stage tool, with a premium flushline connection and the job needed to take place within 72 hours in order to avoid downtime and meet gas delivery commitments.
SOLUTION: Citadel’s DEVGRU team was up for the task. A highly modified Stalwart HD was designed to meet the requirements. The Stalwart HD is Citadel’s production stage tool, of which the 5.500 tool has a 6.830 OD which was too large for the 6.750 hole ID in this case. To meet the 14 ksi requirement for this application the OD could be reduced down to 6.625, but would have been an extremely narrow annulus for stage cementing. To further reduce the OD, steel was identified that met the yield requirements for P110 and Q125 so that the OD could be further reduced to 6.500 to maximize annular clearance and minimize circulating friction during RIH and cementing. The tool was designed, manufactured, threaded with a premium flushline connection and on location all within 72 hours. The tool was RIH on top of the shot joint and successfully screwed into the top of the fish at 6,026’ with 18,800 ft-lb and confirmed with 30-kip overpull. The Stalwart HD was opened hydraulically with 2,700 psi, establishing circulation. Cement was pumped and the tool successfully closed at 1,500 psi over FCP. After WOC, the tool was drilled out in less than 2 hours and successfully pressure tested to 9,000 psi. As a part of the production string, the tool was a part of the frac, pressure tested to 13,000 psi and surviving 80 stages at 12,600 psi.