Economic and Technical Features of a Revolutionary Chemical Scale Inhibitor Delivery Method for Fractured and Gravel Packed Wells: Comparative Analysis of Onshore and Offshore Subsea Applications

The deposition of scale, such as carbonates and sulphates, in production facilities represents a serious operational problem that can result in significant well productivity decline. Currently implemented scale control strategies can involve significant capital and operational expenditure. Development work, involving laboratory testing and a field trial, has demonstrated the technical benefits of a revolutionary method of downhole scale inhibitor delivery. Economic analysis indicates that significant benefits can be derived for a variety of field development and well completion types. The greatest economic benefits would be realised for subsea and minimum facility installations with high intervention costs, where squeeze delivery of scale inhibitor or mechanical workover are used for scale control. In addition, major economic benefits can be realised for horizontal wells with unfavourable pressure regimes, multilateral type completions, multiple fractured wells, and many conventional completion types. The new chemical delivery method offers cost reduction through reduced deferred oil, efficiency of chemical usage, and elimination of coil tubing and intervention vessel use. Economic analysis has indicated that fracturing a well and deploying proppant impregnated with scale inhibitor, is economically preferable to a strategy of squeeze treatment for some conventionally unfractured wells with high intervention costs, for example subsea wells. An additional economic benefit of proppant impregnated with scale inhibitor (Chemflow TM ) is increased well productivity. The benefit is derived from the combined effect of improved get breaking, and scale inhibition during well clean-up. This has been demonstrated in laboratory testing and would appear to be confirmed by field observations. A further benefit of applying scale inhibitor as chemically impregnated proppant is the instantaneous treatment of produced water when water breakthrough occurs. This feature avoids the formation damage that can occur before squeeze treatment mobilisation. In addition, for some applications involving large fractures there is the potential for lifetime well treatment.