Low-salinity waterflooding (LSF) has been recognized as an IOR/EOR technique for both green and brown fields in which the salinity of the injected water is lowered for particular reservoir properties to improve oil recovery. While providing lower or similar UTC's low salinity projects have the advantage of lower capital and operational costs as compared to some more expensive EOR alternatives.This work describes LSF experiments, field-scale simulation results, and conceptual design of surface facilities for West Salym oil field. The field is located in West Siberia and is on stream since 2004. Conventional waterflooding was started in 2005 and current water cut is currently above 80% in the developed area of the field. To counter oil production decline a tertiary Alkaline-Surfactant-Polymer (ASP) flooding technique selected for mature waterflooded field parts and piloting of this technique is ongoing. Operationally simpler and more cost-effective LSF method is considered for implementation in the unflushed (green) areas of the field since it has been recognized that application of LSF in secondary mode results in better incremental oil recovery than LSF in tertiary mode.The results of a comprehensive conceptual study performed to justify the LSF trial are presented in this paper. To generate production forecast for LSF in the isolated area at the outset of reservoir development the results of laboratory core tests executed at different salinities presented earlier have been used. Dynamic reservoir modelling using low-salinity relative permeability curves showed that injection of low-salinity water leads to incremental oil production up to 2.5% of STOIIP. These results establish the fundamentals for a LSF field trial. A concept of surface facilities design for LSF trial area at West Salym oil field is also presented in the paper. Differently to other LSF projects it is proposed to prepare low-salinity water with required properties by mixing fresh water from aquifer and high salinity water from produced water reinjection (PWRI) system. In such a case LSF facilities concept does not require expensive water treatment techniques which significantly reduces the project capital and operational costs.
This paper presents a field-development case study of a lowpermeability turbidite reservoir in Russia. The giant Priobskoye field contains 30°API crude in laminated sandstones of 0.1 to 20 md at a depth of approximately 2,500 m. The complex geology, lack of reservoir information and lack of technology availability caused a 20-year gap between discovery and development.The initial pilot development was halted after poor drilling success, thus the operator invested in 3D-seismic acquisition and an integrated, multidisciplinary reservoir modeling and simulation effort. The subsequent development was based on oriented waterflooding patterns and massive hydraulic fracturing, together with an artificial-lift system equipped with permanent pressure and rate monitoring for evaluation and real-time production enhancement.The optimization of operational practices and introduction of fit-for-purpose technologies enabled a production increase from an intermittent hundreds of BOPD to more than 75,000 BOPD in a period of 3.5 years. The exploitation strategy of this pilot area demonstrated commercially sustainable production from the reservoir and will form the basis for full field development.
The Russkoe oil and gas field was discovered in 1968. It is one of the biggest and complex fields in Russia. It has yet to be put to production, however the development is already concerned by a number of geological and operational issues, such as high crude viscosity, remote location (beyond the Polar Circle), considerable heterogeneity, compartmentalization of poorly cemented sandstones as well as the presence of extensive gas cap, bottom water, and thick permafrost zone. OJSC "Tyumenneftegaz", a subsidiary of Rosneft, has been responsible for the pilot works to seek operational solutions for full-field development. Intensive pilot wells drilling and testing have been performed since 2007 in different zones of the field. In 2009-2012 23 wells, including 16 horizontal ones, were drilled in these pilot areas. Additionally cold and hot water injection tests have been conducted in one of the pilot areas. The main goal of these studies was to learn and reduce geological risks and to find an effective system for full-field development. The article presents the data and results of pilot operations as well as the methods and equipment for monitoring of the pilot works including multi-phase measurements of flow rates of producers using Vx tool, measurements of flow rates of injectors, tests of injectivity/inflow profiles in horizontal sections using DTS and PLT systems, measurements of bottom hole pressure dynamics and parameters of PCPs and ESPs using high precision metering systems. Effectiveness of different control and monitoring methods and of different production technologies has been analyzed. As a result applicability of these methods for the development of viscous oil fields under difficult weather conditions has given using the example of the Russkoe field.
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