SPE APOGCE conference preview – Improved Characterisation of Emulsions Associated with Inflow Control Devices
November 17 @ 8:00 am - November 19 @ 5:00 pm
|Paper Title||:||Improved Characterisation of Emulsions Associated with Inflow Control Devices|
|Author Block||:||M.A. Jackson, U. of Western Australia; B. Hoskins, Oilfield Technologies Pty. Ltd.; N. Ling and M. Johns, U. of Western Australia; R. Gudimetla and C. Conitsiotis, BHP Petroleum|
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Water-oil emulsion formation is commonly observed at wellhead chokes and topsides control valves, with the impact mitigated by chemical injection. The presence of emulsions downhole in Pyrenees wells was inferred from their significant production rate impact and confirmed by the uplift observed from downhole chemical injection. The Pyrenees fields are located in the Exmouth sub-basin offshore Western Australia. Through analogy between individual Inflow Control Device (ICD) orifice elements and wellhead chokes, ICDs were suspected as the source. This paper describes experimental confirmation of emulsion formation by orifice type inflow control devices in Pyrenees field horizontal well completions and proceeds to characterise the emulsions formed. A purpose built flow rig combined Pyrenees crude oil and produced water under low shear, simulating reservoir flow conditions, before flowing through an orifice element at rates equal to peak and mid-life production.
ICD Flow Rig General Arrangement (Oilfield Technologies)
With liquid flow rate held constant, water cut was increased in 10% steps from 0 to 100% water content. At low water cuts virtually all the water was incorporated into the emulsion phase. At higher water cuts the proportion of water incorporated in the emulsion reduced resulting in free water and emulsion fractions (refer Figure).
Laboratory emulsions are generally created by techniques including bottle tests and laboratory blenders with agitation applied until a uniform emulsion results as opposed to the limited residence time of the oil and water in the ICD orifice.
A key component of the experimental system is a benchtop Nuclear Magnetic Resonance spectrometer equipped for non-invasive Pulsed Field Gradient measurement of the Droplet Size Distribution of the emulsions formed. The NMR instrument also measured the proportion of water incorporated in the emulsion phase through hydrogen nucleus (1H) spectrometry. Droplet size distribution is a fundamental fluid property that significantly impacts emulsion rheology. The heavy end component of the crude oil was characterised by a novel Enhanced Saturate Aromatic Resin and Asphaltene analysis procedure to facilitate benchmarking of Pyrenees with emulsion formation tendencies of other producing assets. This quantitative demonstration of emulsion formation by orifice type ICDs at near reservoir conditions is novel, as is observation of partial emulsification, and represents initial steps towards generalisation of models for emulsion formation and their transport properties.