Perm Journal of Petroleum and Mining Engineering

Today, 3D seismic surveys carried out in the south of Perm Krai are increasingly focused on identifying and preparing for deep drilling local geological structures, the amplitude of which is often comparable to the accuracy of structural constructions. Based on this, there is a need to develop a new geological and statistical approach that allows assessing the risks associated with the problem of unconfirmability of prepared objects by deep drilling. Minimizing such risks would reduce the number of negative results of exploration and appraisal drilling, which would directly affect the efficiency of the oil and gas producing enterprise in the field of geological exploration for oil and gas. This article proposes one of the options for developing a geological-statistical approach to assessing the accuracy of the structural constructions of the studied area, which allows drawing conclusions about the degree of exploration of the territory under consideration. Based on the results obtained, conclusions were drawn about the correspondence of the structural plans of the reflecting horizons of the southern part of the Perm region with each other. A comparison of the obtained boundary values of discrepancies with the errors of structural constructions estimated from the results of 3D CDP seismic surveys in the south of Perm Krai. This geological and statistical approach can be used to clarify the risks associated with the problem of unconfirmation of the geological and morphological characteristics of structures.

Solutions used in well drilling must have a number of properties that ensure their functionality. Along with cleaning the bottomhole, removing drilling mud, cleaning and cooling the drill bit, they must maintain hydrodynamic pressures in the well to prevent formation fluids from entering the wellbore and absorption of the drilling mud, as well as regulate the formation of a thin filter cake that covers the pores in the rocks being drilled, which prevents them from crumbling. In drilling practice, drilling muds on water, hydrocarbon and aerated basis are used. From the point of view of environmental safety, water-based solutions are preferable. But to ensure the necessary properties of water-based drilling muds, a number of special chemical additives are used, which, being toxic products of long action, have a negative impact on the environment. Currently, the task is to develop new drilling muds that not only ensure the drilling process in any, including difficult conditions, but also do not harm the environment. The economic component of the issue should also be taken into account. In order to obtain new environmentally friendly drilling fluids, as well as to solve the problem of accumulation of food waste, it is proposed to use biodegradable additives obtained from plants or agro-industrial waste. The article presents studies of the effect of bioadditives on the rheological and filtration characteristics of water-based drilling fluids. The effect of plant additives on the viscosity, density, yield point, filtration of drilling fluids, as well as on the formation and thickness of the clay cake is shown. In addition, the possibility of using agro-industrial waste, such as orange and tangerine peel, sunflower seeds, rice and peanut husks, eggshells, as an alternative to polymers currently used to reduce and prevent absorption of drilling fluids is shown. The possibility of using biodegradable additives as potential environmentally friendly and inexpensive additives to drilling fluids is considered.

Reservoir rock almost never consists of a single mineral. Thus, terrigenous deposits contain carbonates, clays and other components in varying quantities along with quartz. True wettability also depends on the liquids contained in the pores, i.e. on the properties of oil and water. Formation oil contains surface-active and polar substances that can be adsorbed by the rock. In this case, the wetting ability of water decreases, and oil wetting ability increases. As a result, oil can behave as a wetting phase, especially in rocks with a high content of organic matter. Formation water can also be surface-active. The study of the wettability of the reservoir rocks surface has been and remains relevant. In the article, consisting of three parts, the role of wettability of the reservoir surface in the methods of influencing the bottomhole formation zone (BFZ) is considered from the standpoint of its general state, disturbed due to water saturation and the course of a number of colmatation processes. The fundamental principles of filtration of reservoir fluids through macro- and micro-open channels of oil and gas reservoirs indicate the preference for a hydrophilic state of their surface for the advanced inflow of oil along the curves of the relative permeability of oil and water. However, the incorrect idea that emerged in the early 1990s about the need for its hydrophobic state in order to reduce the water saturation of the BFZ and the hypertrophied role of capillary forces in this case attracted many specialists to its side and has proven to be stable to this day. The authors consistently outlined the formation of these ideas and the positioned "efficiency" of hydrophobization mainly due to hydrocarbon saturation of the BFZ.

An increase in the productivity of wells at operational facilities is achieved through the use of various geological and technical measures. Hydraulic fracturing (HF) in production and injection wells is one of the effective methods for increasing oil recovery, involving low-permeability zones and interlayers in the development, a mechanism for a wider coverage of productive zones by waterflooding, which makes it possible to convert part of off-balance reserves into commercial ones. According to experts, the use of hydraulic fracturing can increase the oil and gas recovery factor by 10-15%. The Perm Territory belongs to the old oil-producing region of the Russian Federation. To date, more than 60% of the remaining recoverable oil reserves of the fields of the Perm region are concentrated in carbonate deposits. Most of the fields are currently in the late stages of development. These fields, as a rule, are characterized by the presence of undrained zones with residual reserves and low well flow rates. Most of the remaining reserves of the fields are concentrated in low-permeability reservoirs with a high degree of heterogeneity and difficult fluid filtration. Unfortunately, the results obtained in practice do not always correspond to preliminary calculations and do not reach the planned oil production rates. In connection with the above, the problem arises of predicting the effectiveness of hydraulic fracturing operations using mathematical methods of analysis. The effectiveness of hydraulic fracturing is undoubtedly influenced by both geological and technological parameters. In this paper, for the carbonate Kashirsky (K) and Podolsky (Pd) productive deposits of one of the oil fields in the Perm region, using step-by-step regression analysis based on geological and technological parameters, a forecast of the initial oil production rate after hydraulic fracturing was made. Good agreement between model and experimental results is obtained.