Integrated Sand Management Strategy Development: Kinabalu Field

Abstract

The mature Kinabalu oilfield is currently producing 18,000 bopd from a peak of 40,000 bopd in 1998. Field rejuvenation plans include drilling and completing new infill and development wells from both the existing platform and a new platform. Most platform wells are currently producing sand and none have been completed with sand control. Although current levels are less than 10 pptb, sand production has caused erosion issues and lost production due to the need for regular separator clean outs on the existing platform. Sand production is therefore a key risk factor for both existing well integrity and new well completion design. An integrated, practical and pragmatic sand management strategy was developed founded on establishing the causes of sand production, predicting the conditions for sand failure, and ranking both passive and active sand control options. 1D geomechanical models were built from field, core and well data. The sand failure analytical model was initially calibrated against existing well sand production records, then run for the proposed new wells to assess the potential for sand production over the remaining field life. The model was also used to evaluate passive alternatives to active sand exclusion completions. Modelling supported field observations that sand production is closely linked to reservoir depth, completion style, well inclination and, most importantly, depletion level – sand production is unlikely at initial pressure conditions but is triggered by depletion. The sand failure analyses were embedded in an objective screening protocol which was developed to rank sand control options. This considers existing and proposed well completion architecture, facilities design/limitations, and recognises inherent data uncertainties. This systematic methodology allows a consistent, objective and transparent view of benefits and risks across the different sand control system aspects. Key selection criteria were utilised rather than arbitrary decisions based on limited and often unaudited data. The process ensured a best practice, fit for purpose, and structured sand management solution. As the current levels of sand production remain low, and in response to the challenges associated with remedial or retro-fitting sand control, optimised surface sand management will continue to be the preferred solution for all existing wells. Improved bean up procedures have already reduced sand production at well start up after a shut down. Sand production in most new infill and development wells is predicted to be manageable. In the higher risk wells, targeting shallower or weaker sands, installing sand control would be the default position. Yet re-thinking the completion design, optimising surface sand management procedures, managing drawdown and BHFP levels, and taking advantage of favourable stress vectors through oriented perforation can extend the sand free well operating envelopes over life of well production and depletion conditions, reducing or deferring the need for sand control in all but the highest sanding risk reservoirs. The first infill well to be completed with oriented perforations in Kinabalu produced at 2500 bopd on test with minimal levels of sand. Installing downhole pressure gauges in infill wells have improved BHFP control within the critical well pressure operational envelope from the sand failure model. To date the wells have shown significantly lower sand production than historically seen on Kinabalu production wells. Background Field Details The Kinabalu oil field, located 55 km west-north-west of Labuan, Malaysia, consists of three separate accumulations: Kinabalu Main, Deep, and East (Fig. 1). The bulk of the reserves are in the multiple stacked shoreface Miocene sands (F, J, K, L, M, and O) in Kinabalu Main.