Fracturing Treatments of Openhole Horizontal Wells in Western Siberia
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AbstractIn Western Siberia, there is a number of open-hole horizontal wells completed with un-cemented predrilled liners. While many of these wells produced as expected, some wells with horizontal section lengths between 500 to 1100m (effective lengths from 400 to 900m), were producing significantly lower than the offset verticals wells that had been hydraulically fractured with proppant. Decline curve analyses of these under producing wells indicated either high skin value or a limited producing horizontal interval.Various attempts to increase the production by cleaning up the horizontal section of the wellbore (such as acidizing with CT, implosion treatment etc.) showed only small incremental in PI but did not solve the problem of reducing the skin to zero or lower. Technical limits and large financial and operational expenditures, as well as associated production losses made these types of treatments unattractive.Detailed analysis of the formation and production data, selection of top-priority candidate wells with employment of technically sound frac designs allowed the operator to implement propped fracturing treatments as a stimulation method in these horizontal open-hole wells. As a performed risk analysis of the stimulation operations was deemed acceptable, hydraulic fracturing treatments were initiated and to date, the 19 propped fracture treated open-hole horizontal wells in Noyabrsk region of Western Siberia (Sugmutskoe and Romanovskoe field) have shown productivity index [PI] increases between 2 to 4.5 folds. This compares favorably to offset vertical fractured wells with S = -5 (1.8 3.8 folds).This paper describes the unprecedented integrated approach in hydraulic fracturing treatments of horizontal open-hole wells with un-cemented predrilled liners as one of alternative completion methods that may be used in horizontal field development projects.
