Published: 10/10/2017
Published: 10/10/2017
An operator in southwest Algeria drilled the 8 1/2-in section of a vertical gas well with 1.06-sg oil-base mud to 5,203-ft [1,586-m] TVD. An additional 6.6 ft [2 m] was then added to the drill plan to confirm the formation lithology for a 7-in liner shoe. At this depth, a gas kick occurred and caused total downhole losses. Various grades of lost circulation pills with concentrations to 211 lbm/bbl [601.35 kg/m3] were pumped without returns, and the volume of lost mud totaled 6,424 bbl [1,027.7 m3].
After pumping 140 t of various lost circulation materials without success, the operator contacted M-I SWACO and requested a new proposal to solve the downhole losses. M-I SWACO proposed pumping a tandem pill consisting of the FORM-A-BLOK AS pill and the FORM-A-PLUG II plug.
Three tandem pills each consisting of 50 bbl/50 bbl (8 m3/8 m3) were pumped, and the loss rate decreased gradually from total losses to partial losses at a rate of 94 bbl/h [15 m3/h]. A fourth tandem pill was then pumped ensuring that no crosslink reaction or fluid loss occurred while pumping through the BHA.
With FORM-A-BLOK AS pill and FORM-A-PLUG II plug positioned in the loss zone, the operator was able to confirm well integrity and eliminate fluid losses for well control.
After pumping the four pills, the losses were eliminated, circulation was established, well control was achieved with a 1.11 relative density, and operations resumed in the target reservoir. The BHA was then pulled out, and the wiper trip was performed successfully without any issues. A 7-in liner was then set and cemented.
Challenge: Increase well integrity and reduce losses in a well with a gas kick and total downhole losses
Solution: Pump a FORM-A-BLOK AS acid-soluble lost circulation pill and a FORM-A-PLUG II acid-soluble lost circulation plug to prevent losses and regain circulation
Results: Established circulation and obtained a full return after eliminating losses and controlling the well by successfully pumping four tandem lost circulation pills and plugs
