CT services (WL, CTAF, Plug & Perf technologies)

Coiled tubing (CT) is a unit equipped with a flexible continuous tubing. Coil tubing is a promising and developing area in the oil and gas industry and is widely used in technological, as well as workover operations carried out in gas, oil and gas condensate wells. Coiled tubing is successfully used in highly corrosive and high temperatures environments. Coiled tubing replaces traditional sectional drill pipes. Due to its flexibility, coil tubing is able to work in lateral and horizontal bores, providing mechanical and hydraulic connection between the milling tool (drill bit) working at the bottom and surface drill equipment. Technologies using coiled tubing make it possible to involve most of hard-to-recover reserves (HTRR) of hydrocarbons in Russia into development.

PLUG&PERF Technology

It provides for installation of isolating plugs on CT and perforation per one RIH (mainly for high-flow multi-stage fracturing). To form a connection with the reservoir and to isolate previous processing intervals within the only RIH, a cumulative perforator with a composite explosive packer plug is used, which can withstand a pressure drop of at least 700 atm. To activate the packer plug and cumulative perforator, a cable through the CT is used, which transmits various electrical pulses to disconnect the packer plug and cumulative perforator. Both packer plug installation and perforation are performed per one RIH/POOH.

This technology allows to:

• choose promising formation zones for perforation according to data (WL);
• perform frac in an equal-bore casing;
• reduction in the number of RIH (setting plug and perforating within one run);
• minimum time to drill composite plugs and displacing balls.

CTAF (Coil Tubing Annular Fracturing) Technology

Provides pumping frac treatment through a CT annulus. When using this technology, a special bottom hole assembly (BHA), mounted on CT, is applied, which allows multiple resetting during an operation.

The technology has two options:

1. With reusable movable sleeves. Sleeves are set down during the well construction.
2. Without sleeves - in a cemented liner/monobore casing. As a method of secondary opening, hydraulic jet perforation (Sand jetting) is used.

Before fracturing, BHA on CT is activated and the sleeve is opened, or the Sand jetting is performed. Being in the well during frac, it is possible to monitor bottomhole pressure, which allows effectively adjusting parameters of frac pumping. In case of any complications / “sand-offs”, it is possible to wash out the well bore without additional RIH.

Advantages of CTAF Technology:

• Controlling bottomhole pressure during the frac treatment;
• In the case of “sand-off”, quick cleaning wellbore out of proppant;
• Opportunity to increase stages.

Miscellaneous CT operations available

Flushing the well bottom and well production testing
The operation, allowing to eliminate hydrated, paraffin, proppant and sand plugs in the well, to eliminate complications during hydraulic fracturing and to put the well into operation as soon as possible
Milling frac ports and testing after multi-stage hydraulic fracturing
One of the most common CT operations. The essence of the operation: BHA is RIH into the horizontal trunk, which allows dividing the reservoir into the required number of sections isolated from each other by packers. Then, alternately, with the help of balls, circulation valves are opened and frac is carried out. After multi-stage hydraulic fracturing, a number of operations are performed, also using coiled tubing, such as removing proppant from the completion BHA, milling frac ports (balls and seats), and inflow stimulation from the reservoir
Well-logging (WL) on a flexible continuous tubing (CT)
Coiled tubing will allow WL to be carried out by autonomous instruments and on-line (CT with cable) in steep or highly curved wells, wells with horizontal ending, and / or wells under pumping with high fluid / gas flow rates. In addition, coiled tubing allows data collection (recording bottomhole pressure, zenithal, azimuthal angles and temperature when processing the bottom-hole formation zone and conduct hydrodynamic studies.
Hydro jet perforation (HJP)
Use of kinetic energy of jets of gel-sand suspensions formed in nozzles of a sandblasting perforator. High-speed gel-sand jets have an abrasive effect, which allows direct and effective action on the casing, cement stone and rocks, creating channels of different orientations in them. The sand-sand mixture is pumped into the CT by a pump unit under high pressure. There are many advantages to this operation: safe technology, does not create fractures in the cement stone, does not condense the walls of perforation channels and does not contaminate the channels with explosion products, creates an extensive opening-up zone and volumetric cavities
Bottom-hole zone treatment
Treatment of wells with large heterogeneous intervals of the carbonate reservoir. Acid treats only highly permeable layers and with each new treatment with living acid, existing channels and cavities expand. In this regard, the use of coiled tubing in combination with diverting technologies, such as bulk foam acid treatment of the formation, treatment of the formation with thickened acid, the use of self-deflecting compositions, etc. is required.
Cleaning tubing with a hydraulic monitoring tool
This tool removes contaminants, salt deposits, cement, paraffins, resins and other deposits.
Multi-bore wells treatment
For processing multi-bore wells, a “coiled tubing orientation complex” is used, which is controlled by fluid flow and has adjustable rotation steps around the axis
Acid Jet Drilling
The method consists in creating lateral bores in the productive zone using the natural property of carbonate rocks to dissolve in hydrochloric acid. Advantages of the method: targeted impact on individual layers, the introduction of new drainage zones into the development due to the intersection of remote fractured zones by the bores, as well as bringing the acid to a remote zone of the reservoir
Fishing jobs
Emergency operations with hydro-fish, the use of hydraulically released outer and inner tubing heads, the extraction of wireline and wire, work in wells with overpressure at the wellhead, etc.
Repair and insulation works
RIWs using coiled tubing include work with polymer, silicate, organosilicon compounds, resins, microcement. Coiled tubing allows you to install and drill cement bridges through the tubing string using freezers and expanders
Emergency drill pipe and tubing cutting
If necessary, with the help of coiled tubing, you can cut off tacked HWDP and TBG directly above the sticking point. Advantages: no negative impact on the production casing during the work process, no tubing deformation in the shear area, which facilitates subsequent fishing jobs.