Material for publication as a Communication must be on an urgent matter and be of obvious scientific importance. Rapidity of publication is enhanced if diagrams are omitted, but tables and formulae can be included. Communications receive priority and are usually published within 5-8 weeks of receipt. They are intended for brief descriptions of work that has progressed to a stage at which it is likely to be valuable to workers faced with similar problems. A fuller paper may be offered subsequently, ifjustified by later work.Manuscripts are usually examined by one reteree and inclusion of a Communication is at the Editor's disc re tio n .

This prolific field has enjoyed mineral scale free production for many years but has lately experienced a series of unexpected (and harsh!) calcium carbonate scaling events. Well watercuts are barely measurable yet mineral scale deposits accumulate rapidly within wellhead chokes and flowlines. This paper describes the scaling experience and the challenges of mitigation in an extraordinarily low water cut environment. A detailed analysis of the scaling experience is presented: plant layout, scaling locations, scale surveillance and monitoring programs, laboratory testing, product selection and implementation, and scale inhibitor efficacy surveillance and monitoring programs (and details will be provided on each of these topics). The surveillance and application techniques for scale inhibitor deserve mention as very important lessons were learned for low water cut scenarios. For instance, a heavily diluted scale inhibitor was necessary to be effective and the detailed laboratory and field implementation process is described that led to this key lesson learned. Laboratory testing for chemical selection was performed using classical techniques and identified a polymeric scale inhibitor suitable for the scaling scenario. This is reported in detail, however what could not be tested easily in the laboratory was the effect of <1% water cut and how the product would perform in that environment. A risk managed field surveillance program was initiated to determine field efficiency of the polymer, and involved trialing the chemical on a single well pad using temporary installation of a restricted orifice plate (ROP) to help modify the scale inhibitor residence time (and impact of product dilution) for dispersibility and optimum inhibitor action. The lessons learned from this trial were subsequently rolled-out field wide with very positive results. This paper demonstrates a unique scale formation and control situation that utilized a previously unreported and analytical surveillance approach. The cumulative performance derived by improving not only chemical selection, but the way the wells were managed via surveillance and chemical management decision making processes is compelling and of value to other production chemists working in the scaling arena.

A prolific Southeast Asia onshore oilfield has enjoyed scale free production for many years before recently experiencing a series of unexpected and harsh calcite scaling events. Well watercuts were barely measurable, yet mineral scale deposits accumulated quickly across topside wellhead chokes and within downstream flowlines. This paper describes the scale management experience, and the specific challenges presented by this extraordinarily low well water cut, low pH, calcium carbonate scaling environment. To the knowledge of the authors, no previous literature works have been published regarding such an unusual and aggressive mineral scale control scenario. A detailed analysis of the scaling experience is provided, including plant layout, scaling locations, scale surveillance and monitoring programs, laboratory testing, product selection and implementation, and scale inhibitor efficacy surveillance and monitoring programs. The surveillance and application techniques themselves are notable, and feature important lessons learned for addressing similar very low water cut and moderate pH calcium carbonate scaling scenarios. For example, under ultra-low watercut high temperature well production conditions, it was found that a heavily diluted scale inhibitor was necessary to achieve optimum scale control, and a detailed laboratory and field implementation process is described that led to this key learning lesson. The sudden and immediate nature of the occurrence demanded a fast-track laboratory testing approach to rapidly identify a suitable scale inhibitor for the high temperature topside calcium carbonate scaling scenario. The streamlined selection program is detailed, however what could not be readily tested for via conventional laboratory testing was the effect of <1% water cut, and how the product would perform in that environment. A risk-managed field surveillance program was initiated to determine field efficiency of the identified polymeric scale inhibitor and involved field-trialing on a single well using a temporary restriction orifice plate (ROP) to modify the residence time of the injected chemical. The technique proved very successful and identifed that product dispersibility was important, and that dilution of the active scale inhibitor had a positive effect on dispersibility for optimum inhibitor action. The lessons learned were rolled out to all at-risk field producers with positive results. The ongoing success of this program continues and will be detailed in the manuscript and presentation. This paper demonstrates a unique situation of calcium carbonate scale formation and control that utilized a previously unreported and analytical surveillance approach. The cumulative performance derived by improving not only chemical selection, but the way the wells were managed via surveillance and chemical management decision making processes is compelling and of value to other production chemists working in the scaling arena.