At the present time the geological and hydrodynamic simulation is a standard tool for the analysis and design of oil and gas field development. Usually the full-field models are used for reserves estimation and preparation of Project design documentation. In addition, lots of enterprises use geological and simulation models (G&SM) for operational purposes such as adjustment of current well scheme, planning of wellworks etc. Using the G&SM for these purposes requires their constant operational updating on the newly received geological and geophysical information. These models are called as continuously updated geological and simulation models (CUG&SM). In order to construct such models and improve the predictive capability we apply approaches that are different from approaches that are used in preparation of project documents for undergoing the state examination. This paper reviews alternative approaches to improve the quality of G&SM in terms of oilfields of LLC "JC "RUSVIETPETRO", located in the Central Khoreyver Uplift in the Khoreyver depression area in the northern part of the Timan-Techora Oil and Gas province. Due to the high heterogeneity of carbonate reservoirs, high anisotropy properties and high degree of influence on the petrophysical rock properties (RP) of secondary processes, the applying of standard methodologies of oilfields simulation does not bring any expected results and it may introduce significant errors in estimating of oil and gas reserves. The development of alternative simulation approach is necessary aspect for construction of geological models (GM) which are able to adequately estimate the current geological situation at the oilfields. The developed algorithm requires the adaptation to each new object of study depending on the availability of input data and the geological aspects, only a highly specialized tool can provide high predictive capability under the conditions of fractured porous cavernous carbonate reservoir. For the distribution of RP in the interwell space, a special simulation algorithm with the neural networks, based on the wells and seismic data, has been developed. For the construction of a curve Pc in wells, we apply an artificial neural network (ANN). ANN is trained by means of neuron and gamma logs and results of core studies. In this case, ANN is used to solve the problems of porosity prediction and optimization of operational process. To recover properties in interwell space at a minimum of priory information and to estimate earth parameters based only on seismic and well data is possible by applying genetic inversion. In this case ANN are not programmed in usual way, they are trained by means of known data – seismic roads in the well area and logging. During the process of training ANN is able to analyze, identify and summarize complex nonlinear functions and calculate values that are not in the training set. This algorithm relates to express method of elastic properties estimation. Based on the developed GM, the optimization of well location was carried out. The actual drilling results confirmed the correctness of the taken decisions. The G&SM was developed, the conformity of planned and actual fluid flow rates, water cut, Rp dynamics proved the high efficiency of the method.

Reserves decline of oil fields with fractured carbonate reservoir is crucially complicated due to formation vertical heterogeneity, occurrence of separate filtration pathways and as a consequence poor sweep efficiency of reservoir development both in vertical and lateral direction. As a result – there is a failure to achieve expected level of recovery factor. To its simplest extent there is no clear understanding of mechanism of reserves recovery, quite how the process of oil displacement happens: either in vertical direction or in a layered way. More uncertainties in the research process are brought by active aquifer, reservoir pressure maintenance system directly below the OWC and nonuniform recovery at vertical scale. The results of systematic survey of sweep efficiency increasing of oil-wet fractured carbonates are reviewed on the article using the case study of Central Khoreyver Uplift fields (CKU) of LLC «JC «RUSVIETPETRO» company.

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When planning development of fractured oil-wet reservoirs one may encounter a number of difficulties associated with the complexity and heterogeneity of their structure, uncertainty in main factors effecting the development: integral wettability of the rock, structure of the void space, presence and location of faults etc. The only instrument allowing taking into account entirely all factors relevant to the reservoir engineer dealing with such objects is a full-scale simultaion model. This paper reviews new approaches to improving quality of simulation models using the example of fields of the Central Khoreyver Uplift (CKU) belonging to the Timano-Pechora petroleum province. When characterizing the carbonate reservoir of the fields the authors have accepted a concept in whichheterogeneities of formation's properties at various levels were considered: micro-level, meso-level and macro-level. -Thin sections studies, results of routine and special core analysis were used to describe the heterogeneity at the micro-level. The results of PLT studies, selective formation flowtests, statistical processing and calculation of NTG ratio from core crossections were used to perform the heterogeneity analysis at the meso-level (well scale). Genetic algorithms of seismic attributes processing and lithofacies analysis were applied for description of macro-heterogeneities. An approach proposed in this paper is based on the concept of binding heterogeneities of reservoir's structure at various levels in the framework of a single model. It has been applied for modelling several small carbonate fields at Timano-Pechora petroleum province. At the opinion of authors the final forecast accuracy for the considered models is a unique achievement for oil-wet fractured vuggy porous reservoirs. Well locations were optimized, a program of well interventions was proposed, oil production plans were adjusted on the basis of the constructed models. The accuracy of made decisions is proven by actual results of wells drilling and operation.

The main uncertainty for building 3D geologic and process models is distribution of properties in the inter-well space. The fields comprised of carbonate reservoirs are characterized by the complex porous space structure: availability of secondary porosity, cavern or fracture components. The objective of this paper is to increase the accuracy of the prediction of lithology and permeability and porosity of complex carbonate reservoirs applying the method of petroelastic modelling using the example of one of the Central Khoreyver Uplift (CKU) fields. Obtaining 3D geological and process models capable of quality implementation of representation of the fields’ geological peculiarities is necessary for the purpose of the development tasks: decreasing the uncertainties and reducing the development drilling risks. The paper proposes a method for predicting reservoir properties of carbonate deposits of Famennian strata of Timano-Pechora petroleum province on the basis of petroelastic modelling. The basis of the method is the principle of complexing different scale geological and geophysical surveys. The lithological division of rocks and identification of reservoir types were performed for the reviewed carbonate deposits. The detailed volumetric lithological and petrophysical models with subsequent tying the obtained results with the core material lithological survey data were developed under results of the complex well logging survey interpretations. An efficient environment model was selected for the reviewed carbonate deposits and petroelastic modelling was carried out. The criteria for predicting the reservoir properties using the seismic data with application of the amplitude inversion method were formulated under results of the petroelastic connections analysis.