Flow Remediation Solutions for Pipelines
Authors: Abney Laurence , Kalman Mark , Hoogerhuis John , Headworth Colin 
Published: October 2008

Flow assurance problems in flowlines and pipelines include hydrate formation/blockage, paraffin wax deposition, asphaltene deposition and scale formation on the walls of pipelines, all of which impede the flow of produced hydrocarbons and associated well fluids. Conventional means for pipeline remediation to remove these restrictions include periodic and extensive pigging (either through flowline pigging loops or from subsea pig launchers), chemical injection through umbilicals and high performance thermal insulation (syntactic foam, pipe in pipe, and/or pipeline bundles).

This paper presents a review of the types of pipeline restrictions and blockages, and innovative solutions for remediation, including remediation planning techniques, chemicals, debris pick-up gels and intrusive intervention. The intrusive pipeline intervention system conveys fluids directly to the area of any particular problem, using composite coiled tubing and a pipeline tractor.

Two significant factors that restrict the use of an intrusive flow remediation system are the design of the production facility and the reach capability of coiled tubing. Past and current flowline designs have not considered the use of intrusive remediation systems, and to-date the use of coiled tubing as the conduit for an intrusive system has not been practical beyond a total distance of 9000 feet. Advances in composite technology have enabled the manufacture of high performance light coiled tubing, which eliminates or reduces the flowline-to-coiled tubing drag force, allowing for longer distance intervention with existing tractors. Subtle flowline design changes enable intrusive blockage remediation systems to yield significant benefits.

Maintaining flow of oil and gas through production flowlines is vital to successful offshore and onshore operations. Flow assurance engineering has become a significant part of the feasibility and conceptual design stage of projects, and systems such as active heating employing either electric power or heated fluids have been considered as a method for assuring optimum flow. The application of the flow assurance solutions adds substantially to project CAPEX. In the case of chemical injection or pigging, OPEX is increased, and in most cases operational pigging causes a reduction in production during the pigging operation. In deepwater oil and gas developments the additional cost can be significant, particularly for long tiebacks. The remediation solutions presented herein obviate the need for these high CAPEX and OPEX solutions, without increased risk of long term flowline blockage.

Introduction

The risk to hydrocarbon production from the build-up of deposits or blockage in a flowline or pipeline, resulting in the reduction or elimination of the pipeline flow area, is faced every day by the hydrocarbon transportation section of the industry. The flow assurance challenges associated with a deepwater flowline are significantly different from the flow assurance challenges for shallow water or land-based oil transportation pipelines, yet a number of the techniques for flow remediation are applicable to both types of pipelines. In most cases, where a flow path remains through the pipeline, measures can be taken to stop or reverse the deposition or deposit accumulation process.