The Tengiz oilfield is a giant, carbonate reservoir of Devonian to Carboniferous age located in the Pricaspian Basin of the Republic of Kazakhstan. Gas Injection at the Tengiz field began in January 2007 with sweet gas injection as Phase 1 of the Sour Gas Injection (SGI) pilot project followed by sour gas injection as Phase 2. Phase 2 injection began in October 2007, but was interrupted due to initial start up problems. Continuous sour gas injection was achieved three months later in January 2008.The SGI project has four signposts for success: compressor reliability, injectivity, wellbore durability, and reservoir performance. The sour gas compressor at Tengiz was the first of its kind and has had greater than 90% availability when the Second Generation Plant (SGP) has been operational (SGI injection gas is produced through SGP). Injectivity has exceeded expectations and wellbore durability has also been excellent. Reservoir performance is a longer term signpost which is monitored though an extensive surveillance program. The Tengiz Reservoir appears to be performing as expected to the sour gas injection.The SGI project is a first-contact miscible gas injection process consisting of seven inverted five-spot patterns. To expedite data acquisition, the SGI well patterns were designed to include one "super-spot" pattern (twin injectors 100 m apart providing dedicated injection support to different geologic layers) and three short-spaced producers (producer-injector spacing approximately 1/3 of the standard spacing). Tracers, pulse tests, multiphase meters, gas saturation logs, and production and injection logs are used to monitor and understand reservoir performance. A specialized simulation model (the SGI Monitoring Model) was constructed which uses local grid refinement in the SGI pattern area. This model is used to determine how well the reservoir characterization is able to capture the dynamic reservoir response to the miscible SGI process.An earlier paper (Darmentaev et. al., 2010) discussed preliminary results from the SGI project. The proposed paper will discuss recent results from the reservoir surveillance program, how these recent results compare to the preliminary results, and the integration of all results into our current understanding of SGI performance. In addition, updates to the Monitoring Model, lessons learned and best practices developed since the commencement of sour gas injection will be discussed.

No abstract

New wells were initially cleaned-up directly to the Plant Facilities in Tengiz. The existing facilities were not designed to process well flowback fluids which can contain contaminants, emulsions and solids from drilling and completion fluids. Well flowback operations directly to the process facilities were causing plant upsets and a backlog of wells to be placed on production. An MRM (Management of Residual Materials) spread was introduced in TCO (Tengizchevroil) in 2016 to clean-up new wells prior to performing a Plant flowback. The MRM unit utilizes an EverGreen Burner that performs fallout free and smokeless combustion of liquid hydrocarbons and residual well materials during well clean-ups. Cleaning-up new wells using the MRM spread has significantly improved the number of successful Plant flowbacks per year, lessons learned in all phases have been captured and will be shared. However, MRM clean-ups did not always guarantee a problem-free Plant flowback since only qualitative methods were being used to determine when a well had been cleaned-up sufficiently to be routed to the Plant. To improve the ability to determine a well's readiness for a Plant flowback, new quantitative methods were developed which include continuous sampling and gas-chromatography analysis along with compatibility tests. This paper will share the best practices and challenges during MRM operations, research details, field trial and results that were achieved after optimization of the flowback process.

No abstract

No abstract