Handil field is a giant mature oil field in Indonesia. It's been producing since 1975, being the current recovery factor for oil 49% and 57% for gas. Cumulatively, the total oil produced is around 855 MMstb and gas around 1.68 Tcf. Today, oil is being produced at 20,000 bopd, gas at 75 mmscfd and water at 130,000 bwpd. Enhanced oil recovery projects, infill wells and light workover of existing wells are key elements to maintain field production. This paper describes an innovative light workover intervention, called Annular Squeeze Cement that helps keeping Handil field production performance at its best level. It covers the field study analysis that led to this the technique, some precautions and current challenges concerning the cementing operation as part of light workover activity. It also share lessons learnt from the field execution and evaluation. A case study is also presented for a full understanding how this cementing placement technique contributes to the field performance. This technique was successfully implemented and acts also as one of the important element to extend the life of a giant mature field where economic and success ratio becoming a paramount parameter. Introduction Handil is located at the Mahakam Delta, Indonesia (Fig.1). It comprises 555 hydrocarbon accumulations structurally stacked and compartmentalized deltaic sands. The accumulations are trapped along Handil anticline which is cut by a major impermeable fault dividing the field into two compartments, North and South. Lying 10 km long and 4 km wide at surface, hydrocarbon accumulations are found as shallow as 200 mSS and continue down as deep as 3500 mSS. Handil field is divided into shallow, main and deep zones based on reservoir characteristic and depths as per Fig.2. a. Shallow Zone, above 1,500 mSS, has 160 reservoirs with strong water drive reservoirs which maintain reservoir pressure steady at initial condition. This zone has excellent permeability ranging from 500-5000 mD and unconsolidated sand. b. Main Zone, between 1,500 – 2,350 mSS, has 220 reservoirs with water injection and gas injection to maintain reservoir pressure and optimize oil production. This zone has permeability ranging from 10 – 500 mD and 2 fluids characteristic. Oil reservoirs down from 1500 – 2200 mSS and gas reservoirs between 2200 – 2350 mSS c. Deep Zone, deeper than 2,350 mSS, has low to mid reservoir permeability and mostly gas. As a mature oil field, extensive light workover activities are required to maintain the production in satisfactory levels Fig.3. Light Workovers Operations (LWOs) are well interventions performed without pulling out or replacing the completion of the well, are the most economic technique for this typical brown field. Among the LWO operations executed in the field, a wide cementing squeeze campaign is applied. These LWOs are used to isolate water producing zones and target prospective new reservoir sections. This paper describes how a field study analysis led to improve the workover intervention by an alternative cementing placement technique. It analyzes the main challenges for light workover operations in what regards to the squeeze campaign and finally, it gathers lessons learnt from the designing, execution and evaluation point of view.
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