A revolutionary intervention technique has emerged allowing mechanical manipulation in horizontal wells in combination with field proven Well Tractor® technology.
As Well Tractor® technology has evolved and confidence has increased in the technology during the last few years, the application of a cost-effective method for opening (and closing) of specific down hole hardware (i.e. valves) as an alternative to existing technologies has emerged. The technology is particularily applicable on offshore installations where the logistical limitations are a major consideration. This article will describe the subsequent applications and the process of developing the technology further.
Tractoring eliminates the constraints of traditional wireline operations by extending the reach of the wireline into the horizontal part of the well and thereby allowing operations to be conducted over the entire length of the wellbore and, if necessary, in a rig-less environment. Additional benefits gained are the elimination of mobilizing heavy equipment, which in turn reduces the number of personnel required to run the operation but most significantly reduces the operational exposure to related safety risks. Furthermore, the equipment required is logistically easier to handle and rig-up time is considerably reduced compared to alternative technologies while providing value-creating solutions.
This paper will present the benefits of wireline interventions, particularly in deviated and horizontal wells, the tractoring solution and case histories exemplifying the advantages of this technology.
Introduction
In the following, we will present some of the steps forward in 'cure' technologies where the completion is manipulated in a manner that previously was feasible with coiled tubing or drill pipe in highly deviated wells only, or that were not feasible at all, even in vertical wells.
Wireline Tractor Technology
When first introduced to the market, the wireline tractor (see Figure 1) was used primarily for conveyance of diagnostic logging tools and traditional 'cure' technologies such as perforation and plug setting. However, as it achieved a reliable track record, the technology began to form part of many oil companies standard 'toolbox'solutions.
The wireline tractor functions with an electric/hydraulic power relationship. The control panels, communications and internal power source are electric, while the remaining parts and functions are hydraulic.
When activated, the wheels are hydraulically deployed out of the tractor body and automatically start to rotate. Each wheel contains its own independent hydraulic motor, which facilitates the forward motion in the well. The wireline tractor centralizes itself in the well bore once contact with casing has been established and then deploys intervention tools into the well bore, taking the string beyond its original hang up point. When target depth has been reached, the wireline tractor is powered down. Standard mode for acquiring data is to perform the logging while pulling out of the hole. Aquiring data whilst tractoring is also feasible and produces more accurate flow profiles of producing wells. The passive and immediate fail-safe feature ensures that the wheels are retracted automatically when the tractor is powered down or disconnected.
A number of highly modular tools have been designed to give the wireline tractor maximum versatility in intervention operations.
Well Stroker®
The wireline well stroker (see Figure 2) is typically used in conjunction with a wireline tractor and allows operators to carry out mechanical operations on electric wireline in highly deviated and horizontal wells. When combined with the Well Key® or mechanical shifting tool, the wireline well stroker applies an axial force of up to 33,000 lbs, which is then transferred to the shifting mechanism of the down hole valve. The direction of movement, which is bi-directional, is controlled from the surface control panel for the wireline stroker when it is activated.
