Figure - available via license: Creative Commons Attribution 3.0 Unported
Content may be subject to copyright.
Values of the ultimate oil recovery factor for groups of development objects
Source publication
For the conditions of fourteen groups of low productivity, complex features in the carbonate reservoirs of the Volga-Ural oil and gas province were constructed geological and statistical modeling that allows predicting the ultimate oil recovery factor for deposits similar to those studied when solving various development tasks. Based on the conside...
Similar publications
Determining the reliable values of the filtration parameters of productive reservoirs is the most important task in monitoring the processes of reserve production. Hydrodynamic studies of wells by the pressure build-up method, as well as a modern method based on production curve analysis (Decline Curve Analysis (DCA)), are some of the effective met...
Citations
The purpose of the article is to present an algorithm developed on the scientific and methodological foundations of quantitative and qualitative processing of geological and commercial data to implement the procedure for deep identification of deposits.
The developed algorithm consists of two levels: the initial stage includes facility identification by tectonic and stratigraphic characteristics resulting in the formation of a number of megagroups of objects. Then they are subjected to deep differentiation using the elements of data factor analysis, which is carried out together with the monitoring of the highly identical objects. The presented approach to solving the problems of field effective grouping is the most effective due to a comprehensive and reasonable assessment of the groups of facilities formed as a result of modeling. The developed algorithm was tested on example of a number of fields associated with terrigenous reservoirs of the Devonian and carboniferous systems of the Volga-Ural oil and gas province. After two calculation stages the percentage of correctly grouped objects averaged 96.8 %, which is a high result. To make the search for analogous objects qualitative and objective eighteen equations have been obtained that combine twenty parameters describing the geological and physical characteristics of productive formations as well as the physico-chemical properties of the fluids saturating them at the sufficient level of reliability. Based on the results of using the developed algorithm for deep identification of deposits, the authors obtained a number of relevant mathematical dependencies between various parameters, graphical distributions of objects in the axes of the main components, which all together enable efficient and systematic search for analogous objects in the deposits of terrigenous reservoirs of the Devonian and carboniferous systems of the Volga-Ural oil and gas province. Besides, the presented identification diagrams enable successful management of the processes of oil recovery within the micro- and macro-levels of facility distribution in the axes of the main components. They also allow to form a list of general recommendations that will contribute to the optimal development of liquid hydrocarbon resources.
The purpose of the present research is to provide a comprehensive analysis of data on the geological and physical properties of formations and the fluids saturating them in the Volga-Ural oil and gas province using the methods of geological and statistical model ranking. The discriminant analysis conducted on the basis of qualitative criteria (reservoir type and stratigraphic confinement) identified in all cases the zones of uncertainty, which affect the effectiveness of managerial decision-making in the conditions of analog objects. On this score, the results for six models were refined and updated according to the principle of rank uniqueness value calculation by three methods, both for each model individually and for model systems while using them within the obtained distributions of objects in the axes of canonical discriminant functions. Theoretical and practical recommendations were given regarding the use of geological and statistical models in the development of Volga-Ural oil and gas province fields. The results obtained can be used to solve a wide range of practical problems of proactive resource management, which enable effective determination of the best strategy for the successful extraction of residual and hard-to-recover oil reserves. The proposed parameter ranking table allows both to determine the most unstable parameters with a high degree of probability and to level the factor of heterogeneity and disequilibrium of field data. The conducted study established that identification of object association with a particular group in the axes of canonical discriminant functions leads to the formation of the zone of uncertainty. The latter increases the risks of making ineffective managerial decisions when developing different categories of subsoil users’ assets. Using the methods of ranking geological and statistical models, an algorithm for constructing a hierarchical system is proposed, which allows to expand the application field of the results of geological and statistical modeling in the oil and gas industry as well as to reduce the risk of nonrepresentative results.
The article presents the results of analysing geological structure of the Famennian deposits (Devonian) in the Perm Region. Numerical modelling of the distribution of inhomogeneous stress field near the well was performed for the two considered types of perforation. With regard for the geometry of the forming perforation channels, numerical finite element models of near-wellbore zones were created considering slotted and cumulative perforation. It is ascertained that in the course of slotted perforation, conditions are created for a significant restoration of effective stresses and, as a result , restoration of reservoir rock permeability. Stress recovery area lies near the well within a radius equal to the length of the slots, and depends on the drawdown, with its increase, the area decreases. From the assessment of failure areas, it was found that in case of slotted perforation, the reservoir in near-wellbore zone remains stable, and failure zones can appear only at drawdowns of 10 MPa and more. The opposite situation was recorded for cumulative perforation; failure zones near the holes appear even at a drawdown of 2 MPa. In general, the analysis of results of numerical simulation of the stress state for two simulated types of perforation suggests that slotted perforation is more efficient than cumulative perforation. At the same time, the final conclusion could be drawn after determining the patterns of changes in permea-bility of the considered rocks under the influence of changing effective stresses and performing calculations of well flow rates after making the considered types of perforation channels.
