New methods and instruments developed for measurement of rock thermal properties (thermal conductivity, thermal diffusivity, volumetric heat capacity, and coefficient of linear thermal expansion) have provided a sharp increase in the quality of experimental data for reservoirs and surrounding formations. Optical scanning technology primarily provides numerous high-precision, nondestructive, noncontact measurements of thermal conductivity and diffusivity directly on full cores, core plugs, and nonconsolidated rock samples and enables determination of thermal property tensor components and the recording of thermal property variations along cores. The instrument for simultaneous determination of thermal conductivity, diffusivity at formation temperature (up to 250 degC), and three-component pressure (pore, confining axial, and lateral) enables measurements at formation conditions to study thermal property variations during the heating of reservoirs and oil production in thermal enhanced oil recovery (EOR). The instrument for measurements of the coefficient of linear thermal expansion at temperatures up to 250 degC within every temperature interval of 20 degC provides measurements on core plugs that account for rock anisotropy. Application of the new techniques to study more than 8,000 cores from 17 Russian oil-gas and heavy oil fields provided a representative thermal property database for sedimentary rocks saturated by brine, oil, and gas, accounting for rock anisotropy and inhomogeneity as well as formation pressure and temperature. New correlations between thermal and other physical properties were established. The new experimental data demonstrated that previous information on thermal reservoir properties often needs to be significantly corrected. The new instruments provided detailed information on the spatial and temporal variations in the thermal reservoir properties during thermal EOR. Authors used this to construct detailed 4D reservoir models for estimation of reservoir thermal regime, thermal losses, and heat and mass transfer within reservoirs, enabling better design and optimization of thermal methods of EOR.

Exploration has evolved in Western Siberian Fields in recent years, due to demands to maintain production capacity driven in part by increasing energy consumption. The frontiers have therefore extended into the Arctic regions and to the deeper unconventional formations. To ensure a high degree of reliability, safety and efficiency, a more integrated and high-tech approach has been demonstrated to be essential when planning and executing the drilling and testing phases for such complex environments. At the exploration stage the quality of the acquired data must be high to achieve maximium value.Previous exploration work on the Bolshekhetskaya Depression in Yamalo-Nenets Automonomous Area confirmed the geological complexity of the Jurassic and Achimov formations. The deep bedding, low formation permeabilities, abnormally high formation pressures, and complex geomechanics have made the previous well tests with conventional methods unachievable.The 2011P exploration well of the Pyakyakhinskoye field was drilled at 4800 m and featured initial reservoir pressures up to 980 bara with the average permeability of the Jurassic formations less than 0.1 md. Such a combination makes the well unique. As a result of this complexity, an integrated well testing approach was chosen, which included a cased-hole completion with packer and a high-pressure Drill Stem Test (DST) string. This paper presents the 2011P well test planning and execution for the Jurassic and the Achimov Formations of the Pyakyakhinskoye Field, in which four zones were sucessfully tested. The subsurface and surface equipment, well test data quality control (QA/QC), and the pressure-transient analysis are discussed herein. The geological data set included verified initial reservoir pressures and temperatures, horizontal permeability, and downhole fluid sample data. This enabled commercial reserve values to be fully obtained for the first time in the Jurassic and Achimov Formations of the Bolshekhetskaya Depression. The obtained results demonstrate the chosen equipment layout is fully applicable, this selection of equipment and lessons learned will allow execution of more efficient well testing jobs in the future.

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SUMMARYFor the first time, a detailed study of thermal properties (thermal conductivity, volumetric heat capacity, thermal anisotropy and heterogeneity coefficients) of Domanic formation rocks was carried out using the method of continuous non-contact thermal core profiling. Results of the study showed that core samples of Domanic formation are characterized by significant multi-scale heterogeneity and anisotropy. Based on the results of thermal conductivity profiling, continuous high-resolution (1 mm) profiles of total organic carbon (TOC) were obtained, that significantly extended and enriched the results of pyrolysis. Close correlations between thermal conductivity and density, thermal conductivity and sonic velocities were established with the use of well logging data. It allows predicting of rock mechanical properties without core destruction independently of sonic logging data quality (wellbore walls condition, etc.). Detailed profiles of geomechanical properties were reconstructed through established correlations and successfully compared with results of sonic logging along a studied section of Domanic formation. Conducted study shows that combination of traditional study and express high-resolution non-contact thermal core profiling makes it possible to optimize sample collection for laboratory study and characterize formation by high-resolution profiles of different properties of Domanic formation rocks.

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