_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 203995, “Injection and Production Optimization for Tengiz Platform Sour-Gas Injection by Reactive and Proactive Conformance Completions Control,” by Shusei Tanaka, SPE, and Matthieu Rousset, SPE, Chevron, and Yousef Ghomian, SPE, Tengizchevoil, et al. The paper has not been peer reviewed. _ Sour-gas injection (SGI) operations have been implemented in the Tengiz field since 2008 and will be expanded in a future project. Because of limited gas-handling capacity, production at a high gas/oil ratio (GOR) has posed a challenge, resulting in potential well shutdowns. The objective of the study described in the complete paper was to establish an efficient optimization work flow to improve vertical and areal sweep, thereby maximizing recovery under operational constraints. This will be achieved through conformance-control completions that have been installed in many production and injection wells. Introduction The Tengiz field is in northwestern Kazakhstan on the northeast shore of the Caspian Sea. The reservoir extends 20 km2 with an oil column of approximately 1.6 km in a carbonate buildup structure at 3850 m subsea. Tengiz produced oil has a specific gravity of 47 °API with approximately 13% of hydrogen sulfide (H2S) and 3% CO2 in produced gas. At initial reservoir conditions, the GOR was 2,242 scf/STB and oil viscosity was 0.22 cp. At the time of writing, the production strategy follows gas-injection processes in the central to north platform area while depletion drive exists at the platform margin to the slope, where fractures appear to dominate flow dynamics. The production area is maintained above saturation pressure based on surveillance data for both the platform and slope zones. Tengiz SGI With Vertical Conformance Control The authors write that 20% of produced gas at Tengiz field is reinjected into the central platform area, which consists of the Bashkirian (Bash), Serpukhovian (Serp), and Visean A (VisA) formations. As the volume of injected gas increases, the neighboring producers observe gas breakthrough with increased GOR. The high-GOR wells need to be shut in to achieve maximum oil production in the plant. As the number of shut-in wells increases, however, it becomes challenging to meet plant capacity because of a lack of active producers, resulting in loss of production. To avoid production loss, zonal-production and injection-control capability were introduced through conformance-control completions and use of swell packers and sliding sleeves. With completions closed at a high-GOR interval, oil production is expected to be maintained while gas production from the well is reduced. With the extension of the SGI project, capability will exist to control vertical conformance with the planned completion strategy in 38 producers. In addition, 17 injectors also will have vertical conformance-control capability for selective zonal injections.