Production Revamp and Optimization of Mega Rich Gas Condensate Multi Carbonate Reservoirs; Case Study, ADNOC Onshore Fields
Authors: Al Hosani Mariam , Al Bairaq Ahmed , Al-Ameri Ammar , Nabil Ihab , Latypov Eduard 
Published: November 2019

Revamping/optimizing production from one of the Mega gas condensate field with multistack reservoirs requires integrated solutions combined with advanced technologies and best practices. The topic shows the future major options to develop the reservoir either to sustain the current mandate or to ramp up the production from current production to avail more gas to the network due to the high demand. In addition, gas compression station was taken as part of the major future option to study the possibility of extending the gas plateaus.

A detailed study of possible options considered for Mega Gas Condensate reservoir with high CGR was conducted, targeting the condensate rich peripheral area of the field. The core objective was to study the possible options in order to recover the rich components that may have migrated to the field flanks – and in doing so, maximizing condensate recovery and maintaining wet gas production plateau. It worth to mention that the strategy of developing this reservoir also targeting to avail more gas to the network due to the gas demand. All the surveillance data have been utilized and integrated in the modeling efforts and reservoir development plan.

Three major scenarios were evaluated with alternative options for well location and strategies for injection and production pattern. The first scenario was peripheral injection, where peripheral injectors were drilled to maximize the reservoir pressure in the flanks in order to sweep the condensate towards existing crestal producers. The second and the third strategies were staggered and direct line drive cases, where fixed patterns of injectors and producers were drilled in the peripheral area with a dual objective of sweeping condensate and directly accessing bypassed areas.

Extensive sensitivity analyses were conducted to reduce the number of wells from 91 to the final optimized number (22 wells scattered across the peripheral area). Field and well level sensitivity analyses were performed on the optimized selected scenario in order to define the optimum completion, field/well level operating production/injection conditions. This included analysis of blowdown time, production and injection rates, and injection stream composition. Moreover, the study includes several sensitives conducted to avail more gas to the network through under injection, which will associate with condensate dropout/banking issues. This issue will be addressed as part of future SCAL and R&D studies to understand the mechanism of recovering condensate dropped-out in the reservoir.

Sectorization Voidage Replacement Ratio (VRR) study was conducted to improve the intake/offtake balance and further optimize the VRR to minimize and manage the impact with less gas injection due to Gas demand. This is very significant during the implementation and monitoring phase.

The paper discussed about several Issues, challenges associated with the Gas Condensate Field and the integrated plan expected to be implemented in the future including drilling triple lateral (Maximize Reservoir contact), Underbalance Drilling pilot, Hydraulic-fracturing Pilot, Geomechanics stud. Etc.

The complexity of such multi-stacked reservoirs including the heterogeneities in rock and fluid from one side to diverse development strategies requirement on the other side calls for integrated solutions combined with advanced technologies aiming to maximize HC recoveries.