The key economic drivers for the development of several oil fields in the North Yamal-Nenets region were the commissioning of the main oil pipeline "Zapolyarye-Purpe-Samotlor", as well as a regional tax exemption regulation applicable to the mineral extraction tax, valid until the end of 2021. At the same time, the economic decline in 2008 and 2014 forced many oil companies to reconsider their production programs in the region. As a result, geological assessments and operational drilling programs in many fields were postponed, especially studies on complex development sites such as oil rims. As economic conditions for the oil and gas industry improved, the production activity began to increase. However, a continuation of proven work processes revealed disadvantages to meet short term economic targets. A quick assessment showed that a traditional approach to studying geological structures and assessing the current state of oil fringes would be too time consuming. Long study periods will lead to the fact that the main volume of oil will be extracted beyond the horizon of the tax exemptions, which would make projects uneconomical and jeopardizes the implementation plans for filling the new main oil pipeline.

An increasing number of field development projects include rigorous uncertainty quantification workflows based on parameterized subsurface uncertainties. Reservoir model calibration workflows for simulation studies including historical production data, also called history matching, deliver non-unique solutions and remain technically challenging. This work presents an integrated workflow design for brownfield development optimization projects under uncertainty. Challenges related to complex simulation models with long run times are addressed. Proxy modeling techniques are introduced for performance improvement with application to history matching and optimizing field developing scenarios. Selection strategies of multiple history-matched prediction candidates for estimating prediction uncertainties are presented. Workflow designs for history matching require scalable and efficient optimization techniques to address project needs. A structured workflow design is introduced for addressing complex project requirements and to define intermediate milestones for project reviews. Experimental design techniques are introduced for sensitivity analysis and dimension reduction. History matching processes are built on a series of parameter screening and derivative-free optimization techniques. We introduce Markov Chain Monte Carlo (MCMC) techniques for optimization and uncertainty quantification. Rejection filtering is used for selecting alternative prediction candidates in a multi-objective solution space. Field development optimization workflows define challenges due to the nature of a high-dimensional discrete option space. We present a combined usage of experimental design techniques for generating training data sets and proxy modeling techniques for extensively screening a multi-dimensional control parameter space. Visualization techniques are used to present a solution-frontier of optimized field development scenarios meeting multi-objective optimization criteria, e.g., economic field performance criteria as well as field production targets. The structured workflow was designed and applied to an undisclosed field development optimization project. In this paper we describe the motivation and benefit of experimental design and optimization techniques with application in various phases of the structured workflow from history matching to field development optimization under uncertainty. Complexities in prioritizing selection criteria of cross-disciplinary static and dynamic uncertainty parameters included in a multi-dimension uncertainty matrix are discussed under practical integration criteria. Performance criteria for workflow deliveries in time and quality are critical in decision processes for moving forward within the project phases and for delivering supportive results for reservoir project management. We present decision criteria at which workflow stages added computation resources are beneficial and which methods are scalable and support distributed computing-technology for reducing elapsed project time.

Hydraulic fracturing can be widely used for stimulation of gas condensate reservoirs not only in order to improve the Productivity Index (PI) of the well, but also to minimize the condensate banking effect and maximize recovery, therefore ultimate impact the economic success of the production enhancement operations.Understanding the parameters affecting adequate propped fracture geometry is critical to the process. While none or limited influence can be exercised on the hydraulic fracture geometry from the reservoir side, the fracturing materials and the pumping technology at large, now on the disposition to the frac design engineer have ever been improving and will define the level of achievement.The general statement valid for mid perm reservoirs of high pore pressure and relatively high reservoir temperature, that it is very important to create a fairly long and clean, conductive propped fractures is not sufficient, in reservoirs where condensate banking represent a potentially important pressure loss.To counter the effects caused by pressure depletion below dew point that are resulting in multiphase flow and condensate bank creation in the reservoir, maximum conductivity fractures are designed. Further, depending on the drawdown and induced flow rate to the wellbore, non-Darcy effects, flow convergence and proppant damage can be potentially encountered; hence, fractures designed under the concept of "maximizing conductivity" will additionally decrease the well productivity decline.The analysis presented in the paper was based on a combination of data obtained from field measurements, analytical calculation and numerical simulations, modeling in all details the key processes defining the productivity gas condensate reservoir. The first results obtained indicate that the placement of extremely conductive fractures has a definite advantage in both productivity as well as in recovery of liquid hydrocarbons.To conclude -it can not be overemphasized that ensuring good conductive fractures that will ensure minimum pressure drop from multiphase, or non-Darcy flow is critical. Excellent wellbore connectivity by wide and conductive near wellbore fracture paths and maximizing inflow area and minimizing convergence flow effect is not to be underestimated too. The fracture design has to ensure this environment in the initial production phase as well as in years to come when reservoir pressure drop is expected and higher effective stress, proppant crush, fines migration and embedment, are placing additional strain on maintaining the fracture conductivity.

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Авторское право 2015 г., Общество инженеров нефтегазовой промышленности Этот доклад был подготовлен для презентации на Российской нефтегазовой технической конференции SPE, 26 -28 октября, 2015, Москва, 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.