Laboratory Qualification of Induced Mineral Scale Barrier Technology for Zonal Isolation Application in a Northern North Sea Field

Abstract Managing production, and particularly increased water, in mature oil-producing fields is a growing concern, particularly if there is opportunity for hydrocarbon rich production from other production zones. Established isolation techniques predominantly place barriers within production tubing using mechanical methods, or through a full workover, however workover operations for mature wells are often limited by constraints on internal diameters or well integrity, are difficult to plan, and pose technical uncertainties leading to cost overrun, making intervention uneconomical. This paper describes a novel, cost-effective isolation technology where a permanent solid barrier to flow is established within the reservoir, eliminating challenges associated with workover in mature wells. The patented treatment fluid system provides controlled deposition of inorganic mineral scale, within formation pore spaces, to implement permanent zonal isolation. The qualification of an in-reservoir barrier technology for zonal isolation application in a North Sea Field is presented. An independent oil company in the UK sought to resume production in a Northern North Sea well and identified an opportunity for use of the technology. Independent studies, focused on compatibility, performance, and longevity, were undertaken to establish suitability for the proposed application. Industry standard mineral scaling test protocols proved unsuitable for this novel technology and adaptations were necessary, with minor adjustments made to existing test set-up and protocols, particularly with core flood equipment. Compatibility studies indicated that a change of the inhibitor component was required to improve fluid system compatibility at the elevated temperature of the candidate well. Modified core testing confirmed that permeability reduction of more than 99% was achieved. Introducing the technology, from laboratory development to field specific qualification with a potential North Sea application in mind, whilst also highlighting adaptation of established industry standard mineral scale testing protocols, to provide an effective evaluation methodology of this novel solution, which is required to allow operator to progress to field application. The novel technology remains within the scope of the test program and is still under consideration for possible field application pending final qualification tests.