FIELD

Embodiments herein relate to servicing equipment and methods for oil and gas wells generally. In particular, embodiments herein relate to a mobile well servicing system and method for operating wellbore servicing equipment such as for running continuous coiled tubing, electronic submersible pumps, and dynamic temperature sensors (DTS), for conventional jointed pipe and for hydraulic workover applications.

BACKGROUND

Drilling a well for tapping underground reservoirs of oil and gas is an expensive procedure that has made the petroleum exploration industry a competitive one where cost improving advancements are continually sought. Oil and gas drilling is currently most commonly accomplished with rotary rigs using conventional jointed pipe sections. These rigs typically have jackknife type masts that are tall enough to handle up to three stands of jointed pipe and thereby facilitate faster “trips” in and out of the well bore, yet drilling procedures today remain very much the same for the past few decades.

Once drilling is finished and the casing has been cemented in the wellbore, the drilling rig is usually moved, and a smaller, truck mounted service rig is brought in to complete the well. Completing a successful well, namely preparing it for production, typically includes the steps of running casing into the well, installing a wellhead, and installing a production tubing string. Production tubing strings today may consist of continuous coiled tubing (referred to herein as “CT”) carried on a spool on a CT service rig. The CT is injected inside the well casing using a CT injector head to straighten and push the CT down.

Mobile well service rigs with a mast for handling conventional pipe sections are currently being used for well completion. However, most mobile service rigs require separate transport for their respective services, and all are of limited application. For example, current service rigs incorporate a mast for effectively handling pipe strings in and out of the well. No one service rig provider offers a service rig adapted to handle other types of well servicing technology. Mobile rigs for performing CT well servicing also exist, but most CT rigs in use today require the use of a separate crane to manipulate the blow-out-preventer (BOP) and CT injectors that are required for CT servicing. Although there exist rigs which have a collapsible mast along which an injector head which can be raised or lowered without the need of a crane, these rigs suffer from various short comings. For instance, mobile service rigs are typically not adapted for servicing wells with independent CT, that is, CT located off of the rig, or for performing other tasks such as independent snubbing of heavy strings of jointed pipes. Such rigs also require time consuming installation and removal of the injector head and the BOP.

Current mobile service rigs suffer from further disadvantages. They can encounter difficulty in placing production tubing and other production equipment all the way to the toe of deviated wellbores, such as those wells with short vertical depth and long horizontal depth in steam-assisted gravity drainage (SAGD) operations. Such conditions may in turn cause the production tubing and other production equipment to “friction out”, wherein there is no longer sufficient force created by the weight of the tubing in the vertical section of the wellbore to push the tubing in the lateral section of the wellbore farther downhole. When such a situation occurs, the tubing must be “pushed” into the wellbore by applying forces in addition to the weight of the tubing in order to position the production tubing at the desired depth. Such pushing can be performed by a separate jacking rig for jacking the tubing downhole, or installing a heavy pipe or drill collar at a vertical portion of the tubing string to provide additional weight thereto. However, using a separate jacking rig is inefficient and time-consuming, as the jacking rig must be located on-site throughout the completion operations to be on stand-by in the event the tubing frictions out, and the rig must be aligned with and installed on the wellbore when its services are needed. Additionally, use of heavy pipes or drill collars is not always feasible.

Current mobile service rigs also require laborious and time-consuming procedures when rigging in equipment such as heavy weight pipe and/or portable pipe jacking units to position production tubing and other production equipment at surface. Each additional service, and corresponding additional equipment, added to the mobile service rig increases the demands on the oil and gas operator's time, cost, and efficiency.

Further, adding services and equipment to a mobile service rig is difficult, as the commensurate weight increase of each added capability may result in the rig exceeding the maximum permitted seasonal weights for roads leading to and from the wellsite. For example, the masts of current service rigs are typically rated for loads of about 80,000-120,000daN, and heavy-duty masts can be rated for 130,000-150,000 daN, in order to lift heavy tubing strings. Accordingly, the construction of such masts is quite robust and heavy. Such rigs are often over the legal weight for roads leading to and from the wellsite, and operators must acquire permits before to transport the rigs on said roads. Heavier rigs are restricted to being transported during the winter only, which significantly limits the times of year during which certain operations, such as servicing deep wells, can be performed. There is also a significant cost to loading such heavy rigs onto trailers for transportation.

SUMMARY

Therefore, there remains a need for a multi-task service rig system which overcomes the many disadvantages of current mobile service rigs and CT service rigs. The multi-task service rig system should be mobile and combine on a single platform and have the ability to transport and operate equipment for conventional pipe servicing, coiled tubing servicing, snubbing servicing, and electronic submersible pump and dynamic temperature sensors installation, while remaining under the maximum permitted seasonal weights for the roads that the rig is to travel on.

According to one aspect, a mobile well servicing system is provided for performing multiple tasks on wellsite. The mobile well servicing system may comprise a platform supported by a plurality of wheels; a work surface supported by the platform; a first piece of servicing equipment positionable on the work surface and a mast comprising two parallel legs having proximal ends and distal ends. The proximal ends may be pivotally connected to the platform. A lifting point is positioned at the distal ends of the two parallel legs, and a passthrough space is defined between the two parallel legs. A hoist winch assembly has a lifting device connectable to the first piece of servicing equipment and suspended from the lifting point. The mast is pivotable around the proximal ends of the two parallel legs between a first position, with the lifting point positioned over the work surface, and a second position, with the lifting point positioned behind the platform The first piece of servicing equipment is raised off of the work surface of the platform by the hoist winch assembly when the mast is in the first position. The first piece of servicing equipment is then moved through the passthrough space as the mast is moved towards the second position. When the mast is in the second position, the hoist winch assembly lowers the first piece of servicing equipment to a wellhead.

According to one aspect, the two parallel legs of the mast are telescoping between a lowered positioned and a raised position. Each of the two parallel legs may comprise a hollow main leg and a telescoping leg received in the hollow main leg. When the mast is moved from the first position to the second position, the two parallel legs are in the lowered positioned with the telescoping leg received in the main leg. When the mast is in the second position, the two parallel legs are moved from the lowered position to the raised position with the telescoping leg extended from the main leg.

The well servicing system may comprise a second piece of servicing equipment. The second piece of servicing equipment may be moved after the first servicing equipment has been moved to the wellhead. According to another aspect, the first servicing and the second piece of servicing equipment may be connected at the platform and moved to the wellhead together.

According to a further aspect, a method of using a well servicing system to perform well services is provided, wherein the well servicing system comprises a platform supported by a plurality of wheels; a work surface supported by the platform; a first piece of servicing equipment positionable on the work surface; a mast comprising two parallel legs having proximal ends and distal ends, the proximal ends pivotally connected to the platform, a lifting point positioned at the distal ends of the two parallel legs, and a passthrough space defined between the two parallel legs; and a hoist winch assembly having a lifting device connectable to the first piece of servicing equipment and suspended from the lifting point. The method comprises: providing the well servicing system; moving the well servicing system close to a wellhead; raising the mast from a recumbent position where the mast is substantially horizontal to the platform; pivoting the mast around the proximal ends of the two parallel legs to a first position, with the lifting point positioned over the work surface; using the hoist winch assembly, lifting the first piece of servicing equipment off of the work surface; pivoting the mast around the proximal ends of the two parallel legs and moving the first piece of servicing equipment through the passthrough space, to a second position with the lifting position positioned behind the platform and over the wellhead; using the hoist winch assembly, lowering the first equipment to the wellhead.

According to another aspect, the method comprises extending the legs of the mast at the second position to place the mast in a full operational position. The method may further comprise performing a well service involves at least one of: joined pipes; and coiled tubing, while the mast in the full operational position.

According to a further aspect, the well service includes at least one of: installing an electric submersible pump in the well; changing an electric submersible pump; changing power cable in the well; installing a dynamic temperature sensor in the well; and changing a dynamic temperature sensor in the well.

