Perm Journal of Petroleum and Mining Engineering (Dec 2017)
Study of zones of wettability distribution based on lateral logging for oil-bearing Visean reservoirs of the Solikamsk depression
Abstract
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.
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