Caspian Sea Experience of Formation Testing Features to Maintain the Production Growth on Complex Multi-Layered Offshore Brown Fields

The Cheleken Contract Area covers approximately 950 km² and comprises two offshore oil and gas fields in Turkmenistan, Dzheitune (Lam) and Dzhygalybeg (Zhdanov), in water depths of between eight and 42 meters. The fields comprise two elongate anticlines situated at the eastern end of the prolific hydrocarbon Aspheron Ridge. The oil is found in stacked Upper Miocene-Pliocene Red Series reservoirs over a nearly 2000 m interval. The Cheleken structure is a narrow, faulted, doubly plunging anticline. Cheleken has a complex structure and difficult in development. Most of challenges caused by geologic conditions such as multi-layered sandstones bearing different hydrocarbon types (gas, gas condensate, oil) masked by shales; varying depletion due to heterogeneity and reservoir connectivity uncertainties, various H2S content, wax/paraffin deposition, water and gas breakthrough. Sustaining and boosting the production are achieving in cost-effective ways are by application of modern technologies such as Wireline Formation Tester (WFT). WFT initial application is high vertical resolution measurement of formation pressure to monitor the depletion. WFT current pressure profiling is required to optimize the completion strategy since it is one of key parameter to defined packers setting depths and screen types for reservoir production inflow profile management. Multi-well analyses of pressures regimes complimented by fluid typing and characterization including sampling are used to define reservoir lateral and vertical connectivity. Meantime, major objective to run this tool now is fluid identification with ability to acquire representative formation samples if oil reservoir is above saturation pressure. Downhole fluid analysis allows to get in real-time crucial information about reservoir current saturation to control gas and water breakthrough issues. In order to qualify and quantify fluid properties such as CO2, H2S or wax content to react on associated issues with production and manage them in flow assurance workflow, the lab test should be carried out on PVT sample acquired at reservoir conditions. Along with WFT data well and production logging analyzed together to get full field picture for reservoir management decisions. Reservoir dynamic study with formation testing tools is bringing more understanding about reservoir properties in challenging geological environments. Continuous pressure profiling and saturation refinement in multilayered formation is actively used for optimization of well completion and flow assurance strategy. That approach leads to cost effective development and production strategies on Cheleken fields based on cumulative success applications experience [Blinov, 2019].