Maximizing Hydrocarbon Recovery and Water Injection Support through Pattern Reviews Between Injector Producer Pairs in a Large, Complex, and Faulted Brown Field in SE Asia

Abstract

Large, complex and faulted structures often pose substantial challenges in maximizing hydrocarbon recovery. This is largely due to limited understanding of field wide connectivity of reservoir sands, across fault communication, and uncertainty in reservoir fluid contacts due to a fewer well penetrations in early life of the field. In addition, secondary recovery through water injection support brings further complexities in such fields, particularly in stacked reservoirs with multiple sands completed across individual production zones. The work presented in this paper has utilized ‘pattern reviews’ technique in a brown field containing over 500 well penetrations in South East Asia. Pattern reviews have made use of reservoir pressure data, fault maps, sand/shale correlations, salinity variations between formation and Sea water, and injection and production data by carving out specific sections of the field containing injector-producer pairs. The integrated data and analyses have helped establishing connections, or otherwise, between injector-producer pairs across various parts of the field. Time lapse Production Logging (PLT) campaigns were executed to provide additional supporting evidence on flushing of certain reservoir sands in producer wells and preferential injection zones in injector wells. Systematic selection of patterns containing injector-producer pairs across the field has provided a substantial support in our static and dynamic modelling work to establish reservoir/fault connectivity within fault blocks and across the field. This has subsequently helped in history matching production data as well as identifying infill opportunities for bypassed oil. The present work has also helped in optimizing water flood and choosing certain injectors/zones to open/close for pressure support. An understanding on the connectivity between injector-producer pairs has also helped in identifying areas with low recovery and poor sweep. This has paved the way in initiating a pilot project for Polymer injection in this field to help understand incremental recovery in addition to water flood. A successful outcome would initiate field wide polymer injection with a potential of 10's of mmboe incremental recovery from the field. For the first time in field history, pattern reviews have been extensively used as a tool to understand reservoir connectivity and dynamic fluid movements across the field. An additional attempt has been made to use ant track maps to help identify potential baffles and sub-seismic faults. An integrated effort between the various data and disciplines have provided fresh insights into the reservoirs and which would have otherwise been difficult in heterolythic nature stacked reservoirs.