Abstract

Over the past decade the oil and gas industry has seen the applications for capillary tubing expand from basic onshore chemical injection applications to complex and innovative offshore applications that continue to challenge and redefine the boundaries of conventional well intervention methodology. Well interventions in today’s economically challenging environment can sometimes be difficult to justify. Capillary tubing systems have recently been deployed on challenging new projects in Asia Pacific, Europe and the USA to provide operators with an alternative cost effective method to maintain well bore integrity and enhance production.

Typical capillary tubing sizes are 1/4, 3/8, 5/8 and 3/4-inch OD. Capillary tubing systems have three primary applications and functions. The first being semi-permanent installations for the continuous injection of chemicals down hole for production enhancement. Capillary enables effective and cost-efficient delivery of production or stimulation chemicals at precise downhole depths while maintaining full ESD (emergency shut down) and SCSSV functionality. Secondly for reactivating wells that have been shut in due to the loss of SSSV control line integrity. The third being a wide range of work string activities similar to those performed by conventional “Big Coil” units such as:

  • Scale Removal with Acids

  • Solids Removal

  • Gas Lifting

  • Paraffin Removal with Chemicals

  • Hydrate Removal

  • Logging Tool Deployment

  • Cementing

A typical capillary equipment package (Figure: 1 and 2) is comparable to but much smaller than a standard coiled tubing spread with a substantially reduced cost, environmental impact and risk exposure. The small light weight foot print is especially beneficial in conditions with crane or deck space limitations. Capillary equipment can be custom designed to suit most land or offshore applications. Capillary tubing can be installed on a semi-permanent basis or deployed as a work-string for well intervention programs. A specially designed sub-surface safety valve (SSSV) system can enable capillary installation in wells with existing SSSV systems. Installations or well interventions can be performed in a matter of hours in most situations.

New and innovative capillary technologies allow the equipment to be applied to a broader spectrum of well servicing applications. This has the potential for substantial reductions in operating cost, logistical support and risk exposure that can be applied to operating environments worldwide both onshore and offshore. Wells that were once considered plug and abandon candidates due to cost, technical challenges or accessibility may now be candidates for capillary technology solutions.

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