One of the major goals that field planning engineers and decision makers have to achieve in terms of reservoir management and hydrocarbon recovery optimization is the maximization of return on financial investments. This task yet very challenging due to high number of decision variables and some uncertainties, pushes the engineers and technical advisors to seek for robust optimization methods in order to optimally place wells in the most profitable locations with a focus on increasing the net-present value over a project life-cycle. The quest to deliver a good quality advice is also dependent on how some uncertainties – geologic, economic and flow patterns – have been handled and formulated all along the optimization process. With the enhancement of computer power and the advent of remarkable optimization techniques, the oil and gas industry has at hand a wide range of tools to get an overview on value maximization from petroleum assets. Amongst these tools, genetic algorithms which belong to stochastic optimization methods have become well known in the industry as one the best alternatives to apply when trying to solve well placement and production allocation problems, though computationally demanding. The aim of this work is to present a novel approach in the area of hydrocarbon production optimization where control settings and well placement are to be determined based on a single objective function, in addition to the optimization of wells’ trajectories. Starting from a reservoir dynamic model of a synthetic offshore oil field assisted by water injection, the work consisted in building a data-driven model that was generated using artificial neural networks. Then, we used Matlab’s genetic algorithm toolbox to perform all the needed optimizations; from which, we were able to establish a drilling schedule for the set of wells to be realized, and we made it possible to simultaneously get the well location and configuration (vertical or horizontal), well type (producer or injector), well length, well orientation – in the horizontal plane –, as well as well controls (flow rates) and near wellbore pressure with respect to a set of linear and nonlinear-constraints. These constraints were formulated so as to reproduce real field development considerations, and with the aid of a genetic algorithm procedure written upon Matlab, we were able to satisfy those constraints such as, maximum production and injection rates, optimal wellbore pressures, maximum allowable liquid processing capacity, optimal well locations, wells’ drilling and completion maximum duration, in addition to other considerations. We have investigated some scenarios with the intention of proving the benefits of development strategy that we have chosen to study. It was found the chosen scenario could improve NPV by 3 folds in comparison to a base case scenario. The positioning of the wells was successful as all producers were placed in zones having initial water saturation less than 0.4., and all injectors were placed high water saturation zones. Moreover, we established a procedure regarding well trajectory design and optimization by taking into account, minimum dogleg severity and maximum duration for a well to be drilled and completed with respect to a time threshold. The findings as well as the workflow that will be presented hereafter could be considered as a guideline for subsequent tasks pertaining to the process of decision making, especially when it has to do with the development of green oil and gas fields and will certainly help in the placement of wells in less risky and cost-effective locations.
Reservoir compartmentalization identification and initial properties determination are key factors for any development of oil field aspects. These characteristics are largely serving for outlining the type and the number of reservoir fluids setting. They are expected to state initial reservoir pressure and reservoir potential. Assessing the potential fluid presence and its range, for each respective zone, comes to be essential. For the case study, the associated reservoirs consist of different respective borehole potentially effective zones where fluid limits remain ambiguous. The applied method in these commitments consists of exploiting recorded pressure using Modular Formation Dynamics Tester tools (MDT) to analyze the pressure gradients and variation. This device is intended to make real-time discrimination and split up between formation fluids. Objectives in that concern are also to define reservoir compartments based on the analytical analysis of pressure gradients, taking into account the reservoir fluid type. Aims in this investigation are conducted towards the identification of the reservoir initial conditions and the setting of the Free Water Level (F.W.L.) for each interesting zone. Thus, in that context, approach on reservoir heterogeneity can be a key factor.Conducted analysis is related to an oilfield consisting of an anticlinal structure, located in the Saharan platform (South -Eastern of Algeria). This oilfield is part of Hassi Berkine basin. From a sedimentological point of view, the depositional environment has been found as fluvial-continental deposits. Some erosional impacts of the Hercynian discordance were present affecting essentially the top of the Frasnian clays. The main hydrocarbon reservoir consists of the Lower Shaly -Triassic Sandstone Formation (TAG-I): Current designation for the Sahara plateforem Triasic reservoir in the investigated area. This TAGI has been subdivided into three sub-levels: Upper TAGI (TAGI-U), Middle (TAGI-M) and the Lower (TAGI-L).Obtained outcomes revealed several pressure gradients versus depth. According to obtained graphs, and statistically, these gradients elucidate, for the same considered borehole section, significant trends. Important to mention that a substantial difference in pressure was observed between the oilfield boreholes e.g. TAGI-U+M and TAGI-L. The equivalent density of these gradients displays a fluid deposit succession as; oil (TAGI-U+M), water (TAGI-M), and oil (TAGI-L). Lithologically, a stratigraphic barrier between TAGI U+M and TAGI-L has been identified. With a superimposed pressure gradients observed in the two wells (1 and 2), two reservoir compartments have been deduced. Furthermore, using pressure evolution versus depth as well as density record, for each reservoir communicated level; two free water levels (F.W.L.), in addition to the initial pressure, were identified.
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