Perm Journal of Petroleum and Mining Engineering

The distribution of geochemical properties of rocks of the Bazhenov Formation (BF) by area and section has been refined, regularities have been searched, and conclusions have been obtained that have predictive power. Due to the high cost of continuous core sampling and pyrolysis of samples from BF intervals, the fragmentation and heterogeneity of the accumulated information, as well as the high value of knowledge about the oil-generating properties of BF rocks and their changes over the area, there is a need to increase the information content of the database of geochemical core studies and adapt its application in conditions of limited data. To solve this problem, a database of results of geochemical studies was collected and analyzed, consisting of 5272 samples from 123 wells of 32 fields. As a result of the analysis, conclusions were obtained about the oil-generating properties of BF within the study area and the degree of maturity of the organic matter of the rock. Two regression models were developed to predict the geochemical parameters of free hydrocarbon content, residual generation potential and total organic carbon from well logging data. An algorithm was implemented in the Python programming language to automate the calculation process. Using this algorithm and the resulting regression equation, the calculation of geochemical parameters was carried out in 390 wells in the study area that were not presented by core data, which significantly increased the detail and information content of predictive maps of the distribution of parameters over the area. Using the data obtained, a geological and mathematical model was developed for predicting oil content by geochemical parameters. The developed model reflects the probability of oil content depending on the oil source properties of the rocks of the Bazhenov formation in the study area. The developed forecast model included the parameters of the organic carbon content in the rock, the current reservoir temperature and the thickness of the rocks of the Bazhenov formation.

The relevance of the research lies in the approach to assessing the engineering-geological conditions within the local tectonic structures and their role in the formation of the properties of rocks and the state of the massifs composed by them. The formulation of the question regarding the rocks of the red-colored terrigenous formation as a separate object of engineering and geological research allows us to take into account the features of the history and mechanism of development of local structures, as well as their influence on the reaction of rocks in this case. Particular attention is paid to the role of tectonic fracturing as a consequence of the mechanism of development of local structures and its influence on the activation of hypergenesis processes. An analysis of the behavior of rocks during the development of local structures and the response of the massif to changes in the state of rocks and the activation of hypergenesis processes was carried out, which, in turn, determined the engineering-geological situation at the current moment. Particular attention was paid to the assessment of tectonic fracturing, identification of weakened zones and criteria confirming the correctness of their identification. The methods used in solving the tasks were reduced to a comprehensive study of local structures: the study of the history of their development, size, amplitude of uplift of the foundation, instrumental survey of fracturing in outcrops with subsequent construction of a map of fracturing, sampling, laboratory studies of the structure and properties of rocks, fixation of exogenous processes within the structure. The results of the research were the established dependences of the influence of tectonic fracturing on the state of rocks at three levels: the microlevel (the reaction of the minerals of the constituent rocks at the level of the crystal lattice in the form of defects that have arisen); mesolevel (changes in the physical and mechanical properties of rocks); macrolevel (activation of exogenous processes). Thus, criteria have been defined that allow using them to confirm the correctness of the selection of the most fractured sections of the massif. The correctness of the methodology for identifying zones of increased fracturing within local structures is confirmed by the criteria that were used to solve this problem. It can be used as a basis for large-scale geotechnical zoning within local tectonic structures.

An important aspect of hydrocarbon drilling is the use of drilling fluids that remove cuttings and stabilize the wellbore, providing better filtration. The properties of drilling fluids are essential to the success of any drilling operation. Fluids were originally developed to enable and cost effectively rotary drilling in subterranean formations. In addition, drilling fluids were designed to form a filter cake, which was primarily designed to reduce filtrate loss to the formation, was thin, and retained the drilling fluid in the wellbore. One of the most important functions of drilling fluids is to minimize the amount of drilling fluid filtrate entering a hydrocarbon containing formation, which can cause damage to the formation due to changes in rock wettability, fines migration, mud plugging with solids, and formation water incompatibility. To stabilize these properties, a number of additives are used in drilling fluids to ensure satisfactory rheological and filtration properties of the fluid. However, the commonly used additives are hazardous to the environment: when drilling fluids are disposed of after drilling operations, they, together with drill cuttings and additives, are discharged into water bodies and cause unwanted pollution. Therefore, these additives should be replaced with additives that are environmentally friendly and provide superior performance. In this regard, biodegradable additives are needed for future research. The review article presents an investigation into the role of various biowastes as potential additives for use in water-based drilling fluids. The use of waste-derived nanomaterial was considered, and rheological and filtration studies of water-based drilling fluids were carried out to evaluate the effect of waste additives on the performance of drilling fluids.