Institute of Petroleum Engineering

Centre for Gas Hydrate Research Publications

Abstract 141

Hydraflow: Avoiding Gas Hydrate Problems

Haghighi, H., Azarinezhad, R., Chapoy, A., Anderson, R., and Tohidi, B.

SPE 107335 SPE Europec/EAGE Annual Conference and Exhibition, London, United Kingdom, 11–14 June (2007).

Flow Assurance continues to remain a major challenge in offshore production operations. Current methods for avoiding gas hydrate problems are generally based on one or a combination of the following three techniques: (1) injection of thermodynamic inhibitors (e.g. methanol, ethylene glycol) to prevent hydrate formation, (2) use of kinetic hydrate inhibitors (KHIs) to sufficiently delay hydrate nucleation/growth, and (3) maintaining pipeline operating conditions outside the hydrate stability zone by insulation and/or active heating and/or by controlling pressure. 1 However, for many production operations, particularly deepwater fields, those requiring long tiebacks, and mature reservoirs (where water cuts can be very high), the above techniques may not be economical and/or logistically practical. Thus the industry needs novel and improved techniques to tackle flow assurance problems for such challenging conditions. The new approach presented in this paper - HYDRAFLOW- aims to meet this need. HYDRAFLOW is a novel 'cold flow' concept, which breaks from the tradition of straightforward hydrate prevention. Instead, gas hydrate formation in pipelines is intentionally induced and managed, eliminating the need for expensive thermal/chemical inhibition while improving the economics and practicalities of multiphase fluid transport. An experimental analysis of low and high GOR systems for various different production scenarios with and without AA (Anti-agglomerant) have been undertaken as part of HYDRAFLOW concept development. The effect of simulated shut-in on fluid transportability has also been tested. A new experimental set-up for measuring the viscosity of the fluid system under high-pressure conditions has been designed and commissioned in order to evaluate the rheology of the systems under investigation. Results prove that the concept is viable (at least under laboratory conditions), and strongly suggest that HYDRAFLOW technology could offer significant benefits over existing flow assurance strategies, providing a novel low CAPEX/OPEX solution for challenging (e.g. deepwater, long tie-backs, mature fields) operations.

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