Abstract

A light weight intervention technique utilizing electric wireline has emerged as an alternative to existing well intervention methods. Tractor technology enables high speed, low HSE impact and a high degree of precision in production enhancing interventions in onshore and offshore wells. Wireline tractor technology eliminates the limitation on traditional wireline by extending the reach of the wireline into a high angle or horizontal part of the well bore, enabling access to the entire length of the well.

Interventions in challenging conditions such as subsea, deepwater, extended reach, high-yield, heavy oil and deepwater are also enabled whether the hole angles are highly deviated or not. For instance, where slick line or coiled tubing (CT) operations below 20,000 ft can be risky and costly, tractor technology offers a time and cost efficient alternative for valve manipulation, sand clean out and scale milling. Furthermore, interventions have been performed in high temperature wells (388°F), high pressure (>20,000 psi), ERD wells (>30K ft) and high deviations (130°) wells.

Wireline tractor services can be mobilized in a matter of hours and only require a crew of from two to four people, depending on the operation. Transportation can be done in a helicopter to avoid the cost and time of mobilizing a full CT spread such as when cleaning and milling operations are performed without surface fluid handling logistics. Further, lightweight interventions with tractor technology combined with low surface impact left on the environment, allows mobilizations in eco-sensitive regions where heavy methods are not permitted due to the irreversible environmental damage that would be caused.

This paper will present case studies where the HSE impact was significantly reduced by employing lightweight intervention techniques through tractor related mechanical services. One case will be a recent operation of milling barium sulfate scale on electric wireline and removing the cuttings in the same run in the hole. The second case will be milling out a cast iron bridge plug on electric wireline and the third will highlight the world's first wireline tractor intervention from a subsea intervention ship, which provided a much lighter solution for the operator.

Introduction

Horizontal and extended reach wells have become an accepted and often preferred well design worldwide for maximizing reservoir contact, especially in lower permeability or unconventional reservoirs. A key technology which has emerged from an increase in drilling horizontal and high-angle wellbores is that of tractors for down hole conveyance on wireline and coiled tubing. With over 10,000 operations performed worldwide with this technology, it has become a more reliable and preferred conveyance and intervention method for horizontal and deviated wells. Both the wireline and coiled tubing tractors have demonstrated significant cost savings for operating companies when compared to conventional pipe conveyance methods. In addition, tractor technology has enabled additional well intervention capacity for operators by providing alternatives when pipe conveyance or pump-down is deemed not suitable, owing either to the extended operational time involved or to the potential risk of formation damage.

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