CoilFLATE HPHT packers were used recently for a deep, high-expansion, high-pressure cement retainer application in the Gulf of Mexico, a screenless sand-consolidation treatment in North Africa, and a high-pressure, high-temperature straddle packer for a stimulation treatment in the Middle East. In each of these applications, depth correlation was critically important. The wireless DepthLOG CT depth correlation log is used for well logging, perforating, setting sand plugs, bridge plugs or mechanical packers, and for positioning straddle-isolation tools dur- ing selective stimulation treatments (right). This new tool combines a traditional casing collar locator (CCL) to detect magnetic variations at casing joints with pulse-telemetry technology that sends pressure signals to the surface. Subsurface depth correlations are deter- mined quickly and accurately by comparison with baseline well logs. Wireless technology decreases the number of trips into a well, saving up to 12 hours per operation on typical coiled tubing-conveyed perforating and stimulation operations. Flow-through capability provides unobstructed coiled tubing for pumping services and stimulation treatments. The ability to drop ball-type actuators through the DepthLOG tool allows setting or infl ation of CT packers, activa- tion or release of downhole tools, and detonation of perforating guns. In Algeria, Sonatrach was first to use a
CoilFLATE infl atable packer in combination with wireless DepthLOG technology.14
operations in Well MD 264 of the Hassi Messaoud
fi eld with two perforated zones required isolation and stimulation of an underperforming lower interval. To maximize workover economics, this acid treatment had to be conducted without a rig. A separation of only 10 ft [3 m] between
zones at a depth of about 10,000 ft [3,048 m] pre- sented additional challenges. The packer had to be accurately positioned to isolate a high- permeability upper interval from the less permeable lower zone. An initial attempt without DepthLOG correlation resulted in packer inflation across the lower perforations and ineffective treatment-fl uid diversion. The DepthLOG tool was added to the BHA, which was run in the well to a point below the lower zone. Two upward passes while pumping fluid and receiving pressure pulses from the DepthLOG tool clearly indicated casing collar locations. The CoilFLATE packer was positioned at the target depth and inflated to an internal pressure of 4,000 psi [27.6 MPa].
Remedial
Signaler
Processor Signal booster
Battery power for signal processor
Casing collar locator (CCL)
> Depth control. The wireless DepthLOG CT tool uses a traditional casing collar locator (CCL) to detect magnetic variations at jointed casing collars (left). Hydraulic pressure-pulse telemetry transmits data to the surface, eliminating the need for coiled tubing with an electric line installed. Flow- through capability provides an unobstructed coiled tubing string. A signal booster can be added for depth correlation inside casing sizes larger than 7 in. (right).
Set-down weight on the coiled tubing verifi ed complete packer inflation before pumping an acid treatment. This operation created a maxi- mum differential pressure across the packer of about 3,500 psi [24.1 MPa], signifi cantly higher than other infl atable packers can handle.
Immediately after completing the treatment, the packer was deflated, and nitrogen was pumped to fl ow spent acid back while pulling the coiled tubing out of the well. The production tub- ing did not have to be pulled and only one trip was required to achieve a sustained 326%
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Oilfi eld Review
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