An Integrated Approach to Evaluation of Horizontal Completions in Panna Field: A Coning Dominated Heterogeneous Limestone Reservoir

摘要

The Panna field is a heterogeneous limestone reservoirrnconsisting of a thin oil column overlain by a gas cap andrnunderlain by a water column. The reservoir is coningrndominated and the wells show a marked increase in Gas OilrnRatio (GOR) and water cut very early in the productionrnhistory. Horizontal wells were drilled to minimize drawdown,rnand hence coning, and maximize recovery. The initialrnhorizontals had openhole completions and displayed a peculiarrninflow performance curve that was concave upwards andrnalmost flat at the higher rates. This was thought to be causedrnby the formation of water sumps at low rates, due to thernundulating profile of the drainhole & the low fluid velocities,rnwhich resulted in a non-uniform flow contribution along thernhorizontal. Subsequent wells were completed with arncentralized, selectively perforated tubing (tailpipe) installed inrnthe drainhole and it was thought that this would result in arnuniform flow contribution along the entire horizontal sectionrnand correct the inflow performance curve shape. Analysis ofrnpressure data from the tailpipe wells showed that the tailpiperncaused progressively higher drawdown at high rates. However,rnthe flow distribution along the drainhole could not berndetermined from pressure data alone. A production loggingrncampaign utilizing tractor as the conveyance system had to bernaborted due to a) limited coverage of the horizontal section byrnthe tractor and b) operational problems resulting in fishing ofrnthe tractor in one of the wells. This campaign was expected tornprovide an insight into the flow process in the tworncompletions and determine the most optimum one.rnThis case study presents the performance of the variousrnhorizontal completions in existence in the field and integratesrnproduction and bottom-hole pressure data to explain them.