Well-Completion Techniques and Methodologies for Maintaining UnderbalancedConditions Throughout Initial and Subsequent Well Interventions

摘要

Underbalanced drilling (UBD) is undoubtedly one of thern“hottest” topics in the oilfield today. Although not a newrnconcept, UBD has just recently come of age, as the benefits itrnoffers to the oil and gas industry have been noted only withinrnthe last few years. Underbalanced drilling offers many notablernadvantages, which include:rn1. Reducing formation damagern2. Increasing the rate of penetration (ROP) and bit life.rn3. Allowing the reservoir to be tested and evaluatedrnwhile drilling.rn4. Reducing the number of trips into the holern5. Minimizing differential sticking of pipern6. Limiting lost circulationrn7. Facilitating early production while drillingrn8. Accessing depleted or low-pressure reservoirsrn9. Selecting TD from inflow performance.rnThe benefits of the above are obvious; therefore, they willrnnot be discussed in depth in this paper.rnWhile UBD technology has come a long way since thernearly wells that were brought in via gushers that rose abovernthe wooden derricks, underbalanced drilling can only supplyrnpart of the solution ― once drilling procedures are concluded,rnand the completion phase begins; the primary operationalrndrivers change. Rather than focusing on such activities asrndrilling performance and formation evaluation while drilling,rnthe completion drivers target the reduction of fluid loss and thernelimination of formation damage. Thus, attaining a totalrnsolution requires that underbalanced conditions not only arernmaintained during the completion and for the life of the well,rnbut also throughout any future well interventions.rnUnfortunately, the advances in underbalanced completionrntechnology have lagged behind those seen in underbalancedrndrilling.This paper will explore the strategies, techniques and toolrnsystems required 1) to maintain an underbalanced conditionrnthroughout the initial well completion phase and during allrnfuture remedial operations, and 2), to create a cost-effectivernsolution that will enhance and accelerate maximum reservoirrndrainage.rnTo this end, if underbalanced technology is approached asrna production enhancement technique that starts at the initialrnstage of drilling the well and continues throughout the life ofrnthe well, the end result will be that the value of the reservoirrnwill be increased, and will be collected within in a shorterrnperiod of time.