CASE HISTORIES - HDC-XREAM – Well, Tubing & Valve Recovery Operations

Well 1 – Onshore S. Louisiana – Barium Scale Removal

The first tubing de-scaling operation conducted consisted of removal of scale from tubing above and around a sliding sleeve to allow the operator to access blockages within a production area which included sand control screens within a perforated zone.

The operation entailed 600 gallons of HDC XREAM displaced into the well above the target, with assisted slick line brushes agitating the area of scale exposed. The HDC XREAM was replaced with fresh fluid every three hours until the drift was determined to be wide enough to allow intervention contact with the sliding sleeve with the slick line grapple. Once the drift was widened, the remaining HDC XREAM was displaced into the production area and soaked for 12 hours. The well was lifted with (CTU) and nitrogen and production re-established at the operator’s target production. The operation was completed successfully in 70 hours from start to finish.

The operator had determined that a mixed calcium and barium scale had isolated and sealed up a standing valve located at 14,000' ±. To access this valve it was necessary to de-scale approximately 500' of scale above the valve. The programme used entailed three spotting operations of HDC XREAM across the target area using CT and allowing the soaks to remain in place for 4 hours each. During each soak phase the CTU was pulled out and slick line drift scratcher run to ascertain progress.

During the third soak phase, the caliper of the well was determined that it was open enough to access the valve. The valve retrieval run was successful, with the well brought back to production as planned.

The operation consumed 1086 gallons of HDC XREAM, took 96 hours to complete including rig up and rig down and was highly successful.

Well 3 – Onshore S. Louisiana – Barium, Strontium, Zinc Scale Removal

An aged gas producer lost production capability quite rapidly leading the operator to suspect gradual scale build up and an increasing water cut had finally sealed off the communication from the original perforations to the production string. The tubing was drifted and it was determined an area of tubing below 16,500' ± (approximately 180' above the perforations) suffered the most significant constriction.

From water analysis the scale type projected was barium and strontium sulphate mixed with similar oxides, zinc compounds and corrosion products. HDC XREAM was chosen to remove the scale. HDC was staged in three soaks of four to six hours each for a job requirement total of 385 gallons. The target was the tubing immediately above the perforations and the perforations themselves. The well was supporting a column of water, which was bullheaded back into the formation during operations.

The job was performed as programmed and lifting attempted. The well would not flow and was suspended pending availability of a CTU. On subsequent CTU operations it was found the tubing was bent or collapsed above the perforations and operations were suspended.

Well 4 – S. Louisiana – Mud & Acid Damage Removal & Production Recovery

The client had drilled an HPHT gas well, which experienced severe mud losses in the reservoir. The well losses were cured with massive LCM pills consisting of invert gunk squeezes of bentonite, coarse barite, graphite and various sizes of carbonate material. When finally completed the well did not produce, was acidized with 18% HCL with no result then with HF/HCL again with no response and the acids could not be removed from the well.

The well flowed liquefied formation through the tubing indicating severe adverse reactions.

A Koplus LO/HDC Mark II cake breaking and barite dissolving system was squeezed into the well and allowed to soak in two stages. The well came in successfully at up to 18 mmscfd before coarse solids (gravel and metal) from the well blocked off the choke manifold and tubing. These events indicated the lower completion sand control had failed due to the acids corrosion left in place so the well was suspended. The recovery trend from such a short interval of cleanup indicated the well could very easily produce between 50 and 75 mmscfd.

The operator was very pleased with the result. It demonstrated substantial reserves were in place and even with gross damage, the well could be reversed.