Water Source Identification by SPEC-RFA
Reservoir characterisation and understanding reservoir fluid dynamics are fundamental for effective reservoir management. Identifying active formation zones, distinguishing fracture and rock-matrix flows, and understanding fluid movement from the reservoir to the wellbore is essential for optimal recovery. TGT’s Spectral Reservoir Platform (SRP*) diagnoses reservoir problems away from the wellbore and deep in the reservoir through multiple pipe strings.
The Client drilled a highly deviated oil production well in Q3 2016. The A13 production interval was an oil-saturated reservoir layer with minimum water cut. Once completed and put on production, the well started to produce oil with high water cut. The well reached a production level of more than 1500 BPD with water cut higher than 90%. After employing multiple technologies that could not identify the water source, the Client requested TGT to diagnose this well.
TGT’s technical team worked closely with the Client to analyse the well condition, available survey data and reservoir parameters. The results were inconclusive, and the team proposed to survey the well using TGT’s SPEC-RFA* technology focusing on the sandstone formation, producing layer and shale breaks to identify water-saturated layers. SPEC-RFA* used jointly with proprietary software TermoSim* can analyse and quantify fluid movement behind casing and deep in the formation.
As log data show, the SPEC-RFA* survey detected communication between the perforated zone and the water-bearing zones below and above, possibly due to weak bonds between casing, cement and formation with some contribution from a fracture network.
Based on the above results, the client decided to do a cement squeeze job in order to attempt shutting off crossflow’s thus reducing the total water production.