Nowadays there is observed a global trend of ever-increasing complexity and heterogeneity of hydrocarbon reservoirs. More challenging time makes companies take high-risk decisions based on long-term production prediction. As deterministic approach always gives a single result, it loses its relevance when we deal with risks. Generally probabilistic assessment methodology is coming to the forefront. A new approach called RE-Status (Reservoir evaluation status) has been developed in this study. The methodology is based on probabilistic assessment and along with normal uncertainty technique it includes lithofacies modeling. RE-Status is based on six key parameters that allow us to understand reservoir complexity and level of project definition in terms of reservoir engineering. Geological models were created by combining all geological and geophysical data in order to provide the highest-quality 3D representation of heterogeneous carbonate reservoirs. Evaluation of micro-macro heterogeneities and complex analysis of all core studies were used to derive lithofacies. Systematization of stratigraphic analysis, core descriptions and well logging data allowed us to locate facies in reservoir cross-section. It gave us better understanding of the reservoir and nature of filtration processes. The new approach was applied to two gas fields. Impact of reservoir parameters and lithofacies variability on the dynamics of gas production was described. In the first case RE-Status helped to improve history matching by using facies and uncertainty analysis. In the second case (green field) production prediction based on the results of heterogeneity analysis and facies modeling allowed to locate sweet zones, optimize drilling strategy, increase reliability of forecasting and reduce the uncertainty range. Novelty of the described approach is application of facies modeling to reduce key uncertainties, match the reservoir model to historical data and provide the most accurate forecast of production.

The mathematical model of two-phase displacement of oil by an acid aqueous solution in the neighborhood of a well and a hydraulic fracture [1] was used for investigation processes of optimization acidizing and acid fracturing. It takes into account the kinetics of acid dissolution of a carbonate rock. The proposed model allows us to improve the process of searching and selecting the best design for acidizing and acid fracturing.The effect of well acidizing and acid fracturing are estimated. It is shown possibility to find the best value of such parameters as the speed of injection, speed of reaction and volume of acid mixture injected into a well during acidizing and acid fracturing. At given process parameters in the real case is shown importance of studying the process of interval treatment including the possibility of optimizing the design of each of the treated intervals.The control of such parameters as the injection rate, the chemical reaction rate and the volume of injected acid makes possible to reach the maximum treatment effect at the given solution volume. Also calculations showed that in the case of the acid fracturing the significant slowing of the reaction rate may lead to large leakage of unreacted acid into the reservoir, extending the penetration zone, but also reducing the effects near the fracture and thus worsening the result of treatment.The created model was applied to numerical calculations for real cases. Field and calculated data are in good agreement. Using of this approach allows us to find the ways for new possibilities in improving design of acid treatments and understand the current status of the proposed design. IntroductionAcid treatment is the widely used and effective method of recovery stimulation for oil reservoirs in carbonate rocks. This method makes possible both to clear and extend the porous channels and fractures, to stimulate fluid inflow from the reservoir and to create new voids by dissolving the minerals forming the rock. At the same time acid treatment is an inexpensive and sufficiently simple technology. Process design schemes of the process differ in recipes of compositions, volumes of reagents, the injection rate and pressure, the use of additives for acceleration or deceleration of chemical process.During acid fracturing, the carbonate rock is pickled by acid composition nonuniformly. And the fractures developed by acid fracturing do not require to be fixed by a propping agent since even after closing they have higher conductivity due to the wormholes formed.In the basis of presented paper put a model of the two-phase displacement of oil by an aqueous acid solution [1]. The problem of the design optimization is solved by finding the functions extremums of additional growth of oil rate and NPV (Net present value) depending on the acid volume. Thus it is shown the possibility of growth of effectiveness such effects as acidizing and acid fracturing.

Подход к оптимизации кислотного воздействия на нефтяные пластыВольнов И.А., Сучок С.Н., Обшаров П.А., ЛУКОЙЛ Оверсиз Сервис Б.В.Авторское право 2013 г., Общество инженеров нефтегазовой промышленности Этот доклад был подготовлен для презентации на Конференции SPE по разработке месторождений в осложненных условиях и Арктике 15-17 октября 2013 года в Москве, Россия.Данный доклад был выбран для проведения презентации Программным комитетом SPE по результатам экспертизы информации, содержащейся в представленном авторами реферате. Экспертиза содержания доклада Обществом инженеров нефтегазовой промышленности не выполнялась, и внесение исправлений и изменений является обязанностью авторов. Материал в том виде, в котором он представлен, не обязательно отражает точку зрения SPE, его должностных лиц или участников. Электронное копирование, распространение или хранение любой части данного доклада без предварительного письменного согласия SPE запрещается. Разрешение на воспроизведение в печатном виде распространяется только на реферат объемом не более 300 слов; при этом копировать иллюстрации не разрешается. Реферат должен содержать явно выраженную ссылку на авторское право SPE.

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