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—The potentialities of studying rock wettability by X-ray core tomography are considered using Visean terrigenous reservoirs of the Solikamsk depression as an example. The studies included comparison of the tomograms of core samples in a dry state and saturated of sodium iodide solution, which acts as a radiopaque analog of formation water. Differences in impregnation of the core samples, characterizing their wettability, have been established. According to the tomography data, in the hydrophilic samples the solution filled all pores, except for a small portion of the largest ones. In the hydrophobic samples, there was no impregnation of both small and large pores in the central zone. Based on the tomograms, the rocks were divided into groups by their wettability: absolutely hydrophobic, with strong signs of hydrophobicity, with signs of hydrophobicity, and hydrophilic. Comparison of the results of tomography with the standard approach showed that the Tulbovich method commonly used for the study area does not fully reflect the rock wettability. Comparison of the results of core tomography and study of thin sections with the results of electrometric logging shows their good agreement. The rocks with absolute hydrophobicity established by tomography have an anomalously high electric resistivity, >1000 Ohm∙m, and the rocks with signs of hydrophobicity, >120 Ohm∙m. For the hydrophilic intervals, the electric resistivity values are significantly lower, from 17 to 100 Ohm∙m. Thin sections of the core samples were studied. Their microscopic analysis has shown a higher content of organic matter in the hydrophobic rocks as compared with the hydrophilic ones. Few exceptions might be due to the study of only local thin sections of the samples. Thus, rock wettability can be monitored by electrical methods, especially lateral logging. The results of the assessment of rock wettability by core study and well logging can be compiled for the exploration of Visean deposits of the Solikamsk depression. Geological models constructed with regard to the recognized zones of hydrophilic and hydrophobic reservoirs can be effectively used to optimize exploration of deposits, especially reservoir flooding.

One of the effective methods of oil production intensification for heterogeneous Kashiro-Vereyskian clay-carbonate sediments of the Volga-Ural oil and gas bearing province is proppant hydraulic fracturing. Prospects of realization for this technology are considered in the article on the example of the Vereyskian development object of Moskud’inskoye field. Based on the analysis of rocks samples investigations of Vereyiskian sediments, lithological types of carbonate rocks differing in their structural features are distinguished. Tomographic investigations of rock samples were carried out, as a result of which the rock fracturing for some lithotypes was determined and studieds. Under natural geological conditions, depending on the degree of fracturing progression and technological conditions of development, these intervals may or may not be involved in well operation. When hydraulic fracturing is performed, potentially fractured areas that are not in operation can be successfully added to oil production. Based on analysis of hydrodynamic well investigations, the fracturing of the Vereyskian object of the Moskud’inskoye field was studied on the basis of the Warren-Ruth model. With the help of geological and technological indicators of development, prediction fracturing was obtained, which was used for the construction of the natural fracturing scheme. Areas of both pore and fractured reservoirs development were identified on the deposit area. As a result of statistical analysis, the influence of fracturing on efficiency of proppant hydraulic fracturing was determined. Based on the linear discriminant analysis, a statistical model for predicting the efficiency of proppant fracturing was developed. It was shown that in addition to natural fracturing, the results are most strongly influenced by specific proppant yield, formation pressure, permeability of the remote bottomhole zone and skin effect. Based on the developed model, prospective production wells of the Moskud’inskoye field are identified for proppant hydraulic fracturing.

The relationship between well electrometry data and wettability of Visean clastic reservoirs of the Solikamsk depression was studied. Results of lateral logging with conventional and special core analysis are compared. Theoretical aspects of the influence of reservoir properties, characteristics of the pore space structure and wettability on electrical conductivity is considered. Theoretical calculations of the range of variation of the specific electrical resistance in the conditions of clastic reservoirs of various types are performed. The significant influence of wettability index of surface rocks on the rock resistance is substantiated. The analysis and comparison of different methods for assessing the wettability of rocks from core data are performed. It was found that the greatest errors in rock wettability assessments are associated with hydrophilization of the surface due to core extraction. It is concluded that the X-ray core tomography as a direct method for visualization of pore space in assessing the wettability of operational objects is a perspective method. As a result of generalization of core studies and considered analysis of the development history the geological section with anomalously high specific electrical resistances (200 Ωm and above) is interpreted as predominantly hydrophobic. A section with standard resistance values for clastic reservoirs (less than 120 Ωm) is classified as a hydrophilic type As a result of generalization of core studies and considered analysis of the development history the geological section with anomalously high specific electric resistances (200 Ωm and above) is interpreted as predominantly hydrophobic. A section with standard resistance values for clastic reservoirs (less than 120 Ohm·m) is classified as a hydrophilic type. For the Visean reservoirs (Tl, Bb, Ml) of the Shershnevskoye oil field zonation on distribution of reservoirs of various wettability types is carried out on the basis of resistance values. Schemes of distribution of hydrophilic and hydrophobic reservoirs for the Visean operational reservoirs of the Solikamsk depression can be used to develop design solutions for both production and injection wells.Ключевые слова: удельное электрическое сопротивление, боковой каротаж, геофизические исследования скважин, смачиваемость, гидрофильный коллектор, гидрофобный коллектор, керн, структура порового пространства.Изучена взаимосвязь данных электрометрии скважин со смачиваемостью терригенных коллекторов визейского возраста Соликамской депрессии. Проведено сопоставление результатов бокового каротажа со стандартными и специальными исследованиями керна. Рассмотрены теоретические аспекты влияния на электрическую проводимость фильтрационно-емкостных свойств пород, характеристик структуры порового пространства, смачиваемости. Выполнены теоретические расчеты диапазона изменения удельного электрического сопротивления в условиях терригенных коллекторов различного типа. Обосновано значительное влияние на сопротивление пород показателя смачиваемости поверхности горн...

With an increase in the accuracy of fiber-optic sensors, the possibility of their use in various fields is being formed. In this article, the authors present their own experience in the implementation of fiber-optic technologies in geophysical surveys of wells, indicate current problems and prospects for the development of this direction in the region of activity. Since 2014, LLC “PITC Geofizika” has been actively developing the direction of fiber-optic temperature measurement systems. To date, these are measurements in more than 40 wells (15 wells are being measured at present time). As a result, we can say that today there is already a certain niche in the basket of the geophysical sector, confidently occupied with fiber-optic sensors technologies, but the prospects for the development of this technology are significant and are fully revealed only in the process of work. However, it is worth approaching the implementation of this method only with a complete understanding of the processes occurring in the well.