WFT Applications Experience in the Challenging Geologic Conditions of a Caspian Sea Brownfield to Increase Development and Production Efficiency
Authors: Blinov Vladislav , Hashem Mohamed , Zhangaziyev Zhandos , Binbrek Mohammed , Gibrata Muhammad , Ghedan Shawket , Charupa Mikhail , Ramatullaev Samat , Zeybek Murat 
Published: October 2019

Wireline Formation Tester (WFT) technologies are well known in oil field industry as a major crucial answers provider for formation evaluation especially during appraisal and exploration stages. Meanwhile, their applications are also very useful in the development period of complex brownfields such in the Caspian Sea offshore Turkmenistan to optimize production and increase cost-efficiency. The main challenges caused by geologic conditions including but are not limited as following: multi-layered sandstones with different hydrocarbons types (gas, gas condensate, oil) masked by shales, varying depletion due to heterogeneity and reservoir connectivity uncertainties, some of formations has a low H2S content, increasing water production, gas breakthrough and wax deposition.

WFT provides current pressure measurements and this is important parameter for completion strategy as it defines perforation intervals, packer setting depths and type of screens for reservoir production inflow profile management. Multiwell analyses of pressures survey complimented by reservoir fluids geodynamic study are affording understanding about reservoir connectivity. Downhole fluid analysis allows to get in real-time information about reservoir saturation with formation fluids typing to control in future undesirable gas and water increasing issues. In order to qualify and quantify the wax related issues and manage them in flow assurance workflow laboratory test should be carried out on PVT sample acquired at reservoir conditions. H2S presence is varying across the field and identifying potentially soured layers is required special sampling technique to confirm and exclude them from production. More advanced WFT application such as pressure transient and vertical interference tests provide in situ measurements of effective permeabilities with anisotropy magnitude.

Modern WFT tools were run for years on Djeitun (LAM) and Dzhigalybeg (Zhdanov) fields for production and flow assurance optimization purposes and main applications of this technologies will be discussed here. The benefits of pinpoint pressure measurements and subsequent gradient analysis are vital for analyzing reservoir connectivity. Real time fluid analysis with laboratory accuracy and a wide variety of packer and probe interfaces allow the acquisition of valuable fluid data and representative fluid samples down to quite low permeabilities with preserving reservoir conditions and capturing even extremely low H2S content. Also, years of pressure transient experience has been transported to the WFT environment enabling to derive a rich dataset of permeability what can be used to estimate interval productivity index. Cased hole WFT application allows to obtain information about fluid and reservoir properties in conditions where it was previously impossible in open hole due to technical or geological constraints.