Perm Journal of Petroleum and Mining Engineering

The results of a probabilistic-statistical assessment of the geochemical characteristics of the section of the main oil and gas source strata of the Solikamsk depression and their relationship with the total oil and gas content of the section are presented. For comprehensive accounting and identification of the optimal combination of geochemical parameters that determine the oil and gas content distribution, a complex probabilistic criterion has been developed for each oil and gas complex - Rcomp. Statistical analysis confirmed that the Upper Devonian-Tournaisian deposits in most of the Solikamsk Depression territory were in the main phase of oil formation, and there the maximum mobile bitumen formation occurred, including hydrocarbons, which took an active part in the total oil and gas content formation of the Solikamsk Depression. A fundamentally different nature of changes in the values of the developed complex geochemical criterion has been established in depth for wells located within the oil and gas bearing contours and beyond them. The most informative criterion indicating the relationship between DOM and the total oil and gas content of a section is the bitumen coefficient β.

A promising method for monitoring the process of waiting for cement hardening in wells is the use of fiber optic well thermometry or distributed temperature sensing (DTS). The DTS method creates the opportunity to move from post-facto measurements to real-time monitoring with the identification of complicated areas and timely adoption of the necessary design decisions. As a result of the research, the technology for thermometric monitoring of the process of cement stone formation was developed. The purpose of the work was to determine the applicability of practical skills developed over more than 10 years in the field of production geophysical research using the DTS method to solve the applied problem of well construction. It was established that the data obtained from DTS, in addition to solving applied problems (determining the reaction temperature, data on the result of cementing, etc.), made it possible to solve the problems of monitoring the processes occurring in the annulus during the formation of cement stone and create a platform for the further development of technologies for rapid response to identified complicated areas. The results of the work performed can be widely used in monitoring the well construction process, and are also of interest from the point of view of further development, both from a technological point of view and methodologically.

During the oil and gas reservoirs development, various processes occur, ranging from varying the physicochemical properties of formation fluids to changing the reservoir properties of productive formations, which leads to their destruction. All these processes can influence the final oil recovery in different ways. Research into the influence of clays on the permeability of sandstones has been conducted for more than 50 years, but the presence of clay minerals in reservoir rocks still poses a problem for oil production. When oil is displaced from productive formations, the injected water interacts with the clay minerals of the rock, which leads to significant changes in the dynamics of oil production in the fields. This parameter can especially change when maintaining reservoir pressure by injecting fresh water, since the composition of the injected water significantly affects the permeability of reservoirs. In addition to the type and spatial distribution of clay minerals, another important component that influences the degree of permeability change is fluid composition. Basically, the reduction in permeability occurs when the injected water is less mineralized than the formation water. To establish the dependence of swelling on clay minerals, the work analyzed the results of 1007 laboratory samples that were used to study the mineral composition of clay fractions. To identify the dependence of swelling on various clay minerals, a significant number of graphs were constructed and a relationship was established between swelling and mixed-layer formations of the hydromica-montmorillonite series, which made it possible to establish the swelling values for other fields. To determine the effect of swelling on the change in porosity, a coefficient for reducing porosity due to swelling was introduced. The calculation of oil reserves for the YuV1 layer of 13 fields showed that when taking into account the clay minerals swelling, the value of reserves decreased by an average of 8.6%. It was shown that the injection of fresh water led to the destruction of reservoir rocks of fields with high swelling and low porosity, which was confirmed by the low production of reserves for other fields characterized by opposite values of swelling and porosity. Freshwater injection did not affect production from initial recoverable reserves.