Snubbing – Most advanced drilling technology For the exploitation of new oil and gas reserves as well as for the optimal extraction out of existing wells safe and advanced drilling technologies are used with the help of sophisticated methods, systems and devices. Snubbing is a method for inserting and pulling out tools and tubulars into or out of wells under pressure (live wells). Snubbing is a type of heavy well intervention operation performed on oil and gas wells for which a Hydraulic WorkOver rig (HWO) is used. The rig assist snubbing unit is operated by a reliable control system. So the required tasks can be performed safely against the wellbore pressure. Rig assist snubbing units have a small size and are powerful and flexible for all operations (Figure 1). Because of these advantages snubbing units have become the chosen resource for these types of applications. One of the leading suppliers of these technologies is BALANCE POINT CONTROL BV.

Explosion protected containerized control unit for a rig assist snubbing unit

>> Application Reports

Page 60 | Ex-Magazine 2013

by Sandra Wassink

Pressurized container with integrated heating and cooling (HVAC) and explosion protected battery box

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Containerized Solution For the control and monitoring of snubbing units and to ensure explosion protection a transportable container with the installed technical equipment is an excellent solution (Figure 2). Electromach B.V. in Hengelo, a member of R. STAHL AG, Germany has been specialized in these containerized solutions for hazardous areas and developed a containerized control unit of the rig assist snubbing unit for Balance Point Control BV (BPC). Explosion protection is mainly achieved by type of protection Pressurised Enclosure ›pz‹. A safe atmosphere is achieved inside the container by ventilating clean air into the container and reliably monitoring the overpressure (Figure 3). This technology offers the advantage to use normal industrial devices and apparatus and allows all types of work inside the container without any additional measures of protection. The complete control system for the snubbing unit, developed by BPC, is integrated in the container as well as the operating and monitoring HMIs. The container has been equipped with an explosion protected HVAC (Heating, Ventilation and Air Conditioning) unit and an explosion protected battery system (Figure 4). A complete flameproof fire and gas system is incorporated and the power distribution

Figure 1: Schematic diagram of a rig assist snubbing unit (Source: BPC)

Figure 2: Principle of a pressurized container in hazardous area

Safe area

Hazardous area

Safe areaby pressurization

Figure 3: Control and monitoring system installed in a transportable container with

type of protection pressurization ›pz‹

Traveling Slipbowls

Hydraulic Jack

Work Basket

Strippers

Annular

Blow Out Preventer(BOP)

Rotating Control Device (RCD)

Stationary Slipbowls

system. Above the door of the container flashing lights will warn the platform employees if a malfunction of the system occurs. Also all used junction boxes (8146, 8150 series), lighting (6000 series), emergency lighting (6008 series) and signalling equipment (6161 series) are from the R. STAHL product portfolio. Due to a 15 meter long fresh air-intake hose which has been mounted on the side of the container, fresh air will be drawn out of the safe area for ventilation (Figure 6). The HVAC used in the container has an integrated purge and pressurization unit, which has been placed within the container. Usually the HVAC will be placed on the top side of the container. However in this case, it was necessary to build as compact as possible, and more important the Norsok Standard (Z-015) was applicable, which does not allow any protruding parts. The container was equipped with a Battery Box from Electromach, as a back-up for the BPC installation, based on a 24VDC circuit. In case of a power loss, the Battery Box will maintain the power for about half an hour so the operator can make sure that a controlled shut-down can be performed.

Figure 5: Schematic diagram of a CCTV monitoring system (explosion protected) on a rig with image transmission into the container (standard, for safe area)

Figure 4: Interior of the container with electric and hydraulic equipment

Explosion protected containerized control unit for a rig assist snubbing unit

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HVAV supply duct along roof

Control Room Airlock

HVAC

Ex-B

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Box

Hyd

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Com

part

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Figure 6: 15 Meter long fresh air-intake hose (yellow) mounted on the left-side of the container (left). At the back hydraulic connections and R.STAHL junction boxes (right).

Figure 7: Interior of an explosion protected (pressurized) container with monitoring and operating terminals for controlling and monitoring a rig assist snubbing unit

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On the platform rig multiple explosion protected cameras from R. STAHL have been installed for monitoring the safety of the situation (Figure 5). The container has been equipped with a complete operating and monitoring system. In the container 6 big screens will display the operating process and a real-live image can be monitored using 4 Dome Cameras (EC-750) and 1 Compact Camera (EC-710) (Figure 7). All cameras are implemented and configured by Electromach. The containerized solution for BPC is developed for a zone 2 hazardous area and classified as Ex II 3G Ex de pz [ia] IIB T3. It will be used on an offshore rig and has been built according to the Norsok standard Z-015.

Containerized Solutions Containerized solutions are often used on drilling rigs, as they are very mobile and can be re-used on different locations. Containerized solutions are ideal for applications as this, because all different kinds of techniques, also non-ex, can be used inside the container in a hazardous environment: Ex-monitoring equipment, Ex-cameras and all kind of control units, a complete package in one solution. All Electromach containerized solutions, both zone 1 and zone 2 installation, are fully tested on functionality and explosion protection in accordance with all necessary certification requirements. Aside from assuring compliance with the necessary guidelines, the containerized solutions will drastically reduce the costs of installation at the production facility. The containers are engineered to reduce the costs of ownership and to allow an ergonomically designed workspace and energy efficient design. Electromach’s experience in the past 50 years as system integrator enables to build the complete system including:> Engineering electrical and (3D) mechanical> Software and programming > Procurement of material > Construction and services > Extended FAT (Factory Acceptance Test) > System certification > Documents services, transport and insurance > Commissioning support (SAT – Site Acceptance Test)

These comprehensive services enable minimized project costs, shortened turn-around, one-stop-shopping, and clear certified responsibility for explosion protection.