Well Construction Services (WCS)
Well Construction Services
The cement sheath is vital in that it serves to protect and support the casing and deliver the necessary zonal isolation for the life of the well. And while cementing is conventionally viewed as the last step in drilling operations, WSI also designs cementing solutions as the first step in completions. Throughout the life of the well, the cement sheath is required to withstand the cumulative stresses from well events such as pressure testing, well testing and stimulation treatments.
Well Intervention Technology (WIT)
WSI has an optimal portfolio of services and technologies to perform efficient and effective coiled tubing (CT) interventions. Applications include matrix and fracture stimulation, wellbore cleanout, logging, perforating, nitrogen kickoff, sand control, drilling, cementing, well circulation, and mechanical isolation.
Coil Frac and Stimulation
The CoilFRAC service combines CT and selective fracturing technology enabling multiple zones to be treated in a single trip. In new wells, each zone is perforated conventionally in one wellsite visit. CT is then run in hole with a straddle tool BHA. The bottom zone is straddled, and the fracture stimulation is pumped through the CT string. Residual proppant is reverse-circulated out of the wellbore, and the straddle tool is moved to the next zone, where the process is repeated. Each layer is individually stimulated using only one run into the wellbore.
Wellbore Clean Out
One of the most common applications for CT is the cleanout and removal of fill materials that restrict flow through tubing or casing (at right). Fill material can impede production by blocking the flow of oil or gas. It also may prevent the opening or closing of downhole control devices such as sleeves and valves. Common sources of fill are sand or fine material produced from the reservoir, proppant materials used during hydraulic fracturing operations, debris from workovers
Well logging is typically per-formed with tools that store data in memory; however, some logging operations use an optional cable to provide surface power and readouts when running tools downhole on CT
Endure greater tensile and compressive forces when perforating highly deviated and horizontal wells While known for being flexible, coiled tubing (CT) also delivers a rigidity and strength enabling greater tensile and compressive force endurance, which is a major operational advantage when perforating in highly deviated and horizontal wells or with longer gun strings. Additional gains
When drilling or workover fluids exert hydrostatic pressures that exceed formation pressure, reservoir fluids are prevented from entering the wellbore. Pumping nitrogen gas through the CT string and into the fluid column is a common method for reducing hydro-static pressure within the wellbore to initiate production. The CT string is run to its target depth, and the nitrogen is pumped through the string to reduce the density of the hydrostatic column. When the
Coiled tubing is also used in completion programs to convey downhole hardware, fluids and materials. Frequently, wells drilled in unconsolidated sands require the wire mesh screen of a gravel pack (GP) to prevent sand production. Common GP installations involve a washdown procedure. First, the CT string is run to the GP depth. Gravel is then pumped through the coiled tubing. The CT string is retrieved to the surface, and a GP screen assembly is attached. As the cylindrical screen is run to the top of the gravel, fluid is pumped through the CT to agitate the gravel and settle the screen into place across from the perforations (at bottom right). The CT string is then retrieved to the surface. The GP keeps the sand in place while allowing formation
CT technology has expanded into openhole operations, to include drilling and associated activities. Coiled tubing drilling (CTD) can accommodate a variety of applications, including directional or nondirectional wells. CTD is carried out with a downhole motor and, compared with conventional drilling applications, uses higher bit speeds and lower weight on bit. In directional wells, a steering assembly is required to direct the well trajectory. CTD is used in both overbalance and underbalance drilling applications.
Operators frequently utilize coiled tubing as a conduit for accurate placement of cement downhole. Cement is used for sealing perforations or casing leaks, for primary or secondary zonal isolation and for plugs used in kickoff or abandonment operations. A cement squeeze enables the operator to plug casing leaks or existing perforations by pumping cement slurry under pressure into these openings. The cement fills openings between the formation and the casing, forming a seal. Setting a cement plug involves circulating a cement slurry into position using CT then withdrawing the CT string to a point above the top of cement. A slight squeeze pressure is applied if necessary, any cement remaining in the tubing is displaced by a tail slurry then the CT is pulled out of the hole.
Coiled tubing can help the operator avoid the risk of formation damage inherent in killing a well by allowing continuous circulation during well intervention operations. These advantages may yield significant cost savings over conventional drilling or workover techniques.
Operators also employ coiled tubing to convey and place bridge plugs and mechanical, hydraulic or inflatable packers to establish zonal isolation. This operation is carried on with lower cost compare to workover rigs or other methods of tools conveyance downhole.