Tengiz Sour Gas Injection Project: An Update

Abstract

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.

Prospects of an Acid Gas Re-Injection Process into a Mature Reservoir

“…The results demonstrated a distinct pattern of reservoir response to acid gas injection, showing an increase in reservoir pressure and, thus, in oil production over time. These findings align with previous simulation studies that have highlighted the efficiency of acid gas injection in improving recovery rates in sour reservoirs [45][46][47], as well as with past field experience, such as the Zama field in Canada [48], the Tengiz oilfield in Kazakhstan [28,49] and the ARF and GAF fields located in the Gulf Arab region [28], endorsing the fact that acid gas re-injection can serve as an effective EOR technique.…”

“…Subsequently, larger projects emerged, including AGI initiatives at Sleipner West in the North Sea, In-Salah in Algeria, and LaBarge in Wyoming, USA [16]. Beyond these well-established sites where the injection of sour and acid gas mixtures is common practice [24,25], AGI is now applied to numerous sour oil and gas reservoirs worldwide, such as the North Caspian basin's Tengiz field in Kazakhstan [26][27][28] and the Middle East [29][30][31]. In cases of mature reservoirs containing highly soured resources that have already been produced through primary and secondary recovery, AGI presents a compelling EOR alternative that can potentially circumvent the limitations of waterflooding, as well as provide an eco-friendly option, aligning with global trends towards more sustainable and environmentally friendly industrial practices.…”

“…Subsequently, larger projects emerged, including AGI initiatives at Sleipner West in the North Sea, In-Salah in Algeria, and LaBarge in Wyoming, USA [16]. Beyond these well-established sites where the injection of sour and acid gas mixtures is common practice [24,25], AGI is now applied to numerous sour oil and gas reservoirs worldwide, such as the North Caspian basin's Tengiz field in Kazakhstan [26][27][28] and the Middle East [29][30][31].…”

A Review of Enhanced Oil Recovery Methods Used in the Fields of Kazakhstan

“…Удаленность Казахстана затрудняет экспорт гранулированной и хлопьевидной серы на потенциальные рынки, хотя часть ее продается в Китай, Восточную Европу и Африку. Большая его часть (около 2000-3000 тонн в день) хранится на земле, как показано на рисунке (б) [14]. Кон- Чистая ежедневная добыча ТШО в 2017 году составила 544 000 баррелей сырой нефти, 802 миллиона стандартных кубических футов природного газа и 42 000 баррелей ШФЛУ.…”

Recovery of Flared Natural Gas with High CO₂ Content Using SOFC CHP System: Feasibility Study for Neem-Field, Sudan

“…• First, re-injecting this gas without desulfurization to recover more oil. The re-injection of bulk-CO2 natural gas, has been conducted in many reservoirs, such as the Tengiz oil field in western Kazakhstan [6], while its performance and physical phase behavior have been researched by Congge He et al [7], Jinhyung Cho et al [8] and Anzhu Xu et al [9]. The main benefit of this option is it increases oil recovery where most of the current value resides in unconventional plays, along with the opportunity to produce and sell the natural gas at a later time when the price is more favorable [10].…”