Study of synthesis of hydrogen and hydrocarbons by mechanochemical activation of the surface of mineral rocks

In the light of the eternal discussion regarding the sources of hydrocarbons for the initial oil and gas-forming substance, it is possible to recognize the legitimacy of both organic matter, which is confirmed by the biogenic theory of the origin of oil, and deep gases, declared by supporters of the theory of the inorganic concept, referring to the extraordinary richness of hydrocarbons in the mantle. But, the catagenic stage, the process of obtaining oil from the initial substance, in which the primary carbonaceous substance (often under such hypothetical concepts as “micron-oil”, “fluids”) passes into hydrocarbons in the form of oil deposits, causes no less scientific interest and also insufficiently studied. The author sees it as fair to attempt to put emphasis on predominantly geodynamic conditions, tectonic stresses, physico-chemical and thermobaric conditions, the generation of hydrocarbons, on the basis of the synthesis of hydrocarbons in any geological period. The article proposes the author’s chemical model describing the low-temperature polycondensation synthesis of hydrocarbons from water and carbon dioxide in the process of mechanical reactions on the surface of a rock model.

Enhanced Learning of Fundamental Petrophysical Concepts Through Image Processing and 3D Printing

We designed a multidimensional visual learning project with the primary goal of helping undergraduate students better understand fundamental concepts in petrophysics through a set of exercises centered around an analysis of flooding experiment images. More specifically, we focused on concepts related to the trapped fluid within a rock’s pores in this project. To do this, eight different pore networks with unique internal structures were used and then 3D printed. The models were printed using a transparent resin to showcase the movement of fluids inside the rock model. The fluid’s displacement within the 3D-printed rock model was recorded using a high-definition camera, and still images were taken. Undergraduate petroleum engineering students were then assigned a set of exercises to guide them through an analysis of the pore network model images. Students conducted the analysis through an open-source image analysis software (Fiji) to help explore and better understand fundamental petrophysical properties: porosity, fluid saturation, wettability, grain-size distribution, and displacement efficiency. A survey was given to the students to gauge the effectiveness of the exercise in improving their understanding of these concepts. Survey results illustrated that the project-based learning exercises were effective in helping students to better understand difficult-to-grasp petrophysical concepts as they could be more easily visualized through the captured flooding experiment images and the accompanying analysis. An additional benefit to this unique visual learning experience is the ease at which it can be delivered remotely to adhere to safety measures as a result of the global COVID-19 pandemic.

EVALUATION OF RELATIVE PERMEABILITY OF A TIGHT OIL FORMATION IN DAQING OILFIELD

Relative permeability is one of the most important petrophysical parameters to evaluate a reservoir’s production during primary and subsequent secondary or enhanced oil recovery processes. Yet measured relative permeability data for tight oil reservoirs are very scarce to find in the literature, mainly because the measurement is difficult and time consuming to make. In this paper the protocol and results of water/oil, surfactant /oil, CO2/oil, and N2/oil relative permeability are presented, and compared to the digital core analysis results where wettability was set to water-wet or mixed-wet, as well as the Brooks-Corey model. Amott-Harvey wettability index was measured to explain the differences. The target formation is a sandstone tight oil formation located in Songliao Basin, China. Its permeability is mostly in the 0.01-5mD range. Core and oil samples from the target formation were used in the wettability and relative permeability determination. Relative permeability was measured at reservoir conditions using a customized core flow setup. Core samples were cleaned then wettability restored. To match the reservoir fluid viscosity and avoid changing wettability, stock tank oil was blended with kerosene to reservoir fluid viscosity at reservoir temperature. Relative permeability was measured using the unsteady-state method. Amott-Harvey wettability index was measured on core samples from the same formation at reservoir temperature. Amott-Harvey wettability index results show that the restored wettability ranged from water-wet to oil-wet, with most samples being mixed-wt. The addition of non-ionic surfactant promoted wettability change toward more water-wetness. However, anionic surfactant had little effect on reversing wettability. Oil relative permeability (Kro) results obtained from the digital rock analysis (DRA) assuming uniform water-wetness are consistent with relative permeability calculated from mercury injection capillary pressure using Brooks-Corey model. When wettability of the digital rock model was set to mixed-wet, the resulted Kro matches the measured Kro of a sister plug to the sample used to build the digital rock model, which is consistent with the wettability measurements. The addition of surfactants increased both water and oil relative permeability through wettability alteration and IFT reduction. CO2 flood was conducted as an immiscible flood due to reservoir pressure lower than MMP. CO2 flood left high residual oil saturation compared with water floods. N2 flood left even more oil behind compared with CO2 flood. Relative permeability provides key input parameters for formation evaluation and the subsequent EOR processes such as huff-n-puff operations. There are very little published relative permeability data for tight oil reservoirs. This work extends the relative permeability database, and is a starting point for future EOR work.

Anisotropic Rock Model-Guided Post-Stack Attribute Analysis With Pore Type and Production Data for a Carbonate Gas Reservoir

The Moxi area in the Sichuan Basin is dominated by carbonate gas reservoirs, where gas productivity is most strongly influenced by their pore types. Fractured caves are the most favorable pore structure type for reservoir productivity, followed by cave and vuggy pore structures, and interparticle pore structures are the least productive. The spatial discrimination of these three pore types is important for cost-effective development. However, the pore type identification remains difficult owing to poor-quality azimuthal seismic data. A practical approach is to understand the seismic signatures of the different pore types and the related productivities from the post-stack data. In this work, seismic forward modeling is conducted using a constructed theoretical model of Hudson's anisotropic representation, and the pre-stack and post-stack anisotropy signatures are analyzed for different pore types. The rock model is further calibrated using log data, and forward modeling is performed based on the calibrated logs. We propose a new attribute of these signatures: namely, the ratio of the absolute peak and the absolute trough immediately below the peak, which is applied to the three-dimensional seismic data in the Moxi area. In contrast with other conventional attributes, this ratio effectively correlates with pore type, which allows the pore types in wells to be differentiated. This attribute also reasonably correlates with open flow gas rate of the well. The results demonstrate that this attribute from the post-stack data is a promising indicator of pore type and gas productivity and can also be readily mapped spatially for the selection of new drilling locations.

Simulation of Fractured Rock Heterogeneity with the Grid Characteristic Method Using Structured Multiblock Grids

Основной задачей, стоящей перед сейсмической разведкой, является восстановление структуры и свойств подповерхностного пространства на основе регистрации колебаний земной поверхности. Для этого необходимо решить обратную задачу, что, в свою очередь, требует решения серии прямых задач с последовательно изменяющейся моделью геологического массива. В связи с открытием нетрадиционных месторождений (например, Баженовская свита), актуальной становится задача интерпретации сейсмического сигнала, обусловленной неоднородной структурой трещиноватых пластов. В настоящей работе была построена трещиноватая модель, отражающая некоторые особенности нефтеносных геологических сред. Проведено численное моделирование распространения сейсмических волн и получены синтетические площадные сейсмограммы. Также был проведен анализ сейсмического отклика. The key objective of seismic exploration is the recreation of the subsoil structure and properties by registering the surface waves. To solve a reverse problem, several direct problems shall be solved as the rock model is gradually changed. As nonconventional deposits are discovered (like the Bazhenov suite), it becomes necessary to interpret the seismic response caused by the heterogeneous structure of the fractured rock. This study presents a fractured rock model that represents some features of oilbearing geology. The seismic waves propagation was simulated, and composed widepatch seismic records were produced. The seismic response was also analyzed.

Numerical experiment research on failure characteristics of anchored rock with negative Poisson’s ratio bolt

With the continuous increase of mining depth and engineering burying depth, the nonlinear physical and mechanical phenomena exhibited by rock are also more complicated. The load value often exceeds the yield strength of the traditional Poisson's ratio supporting materials, causing the supporting body to fail. Therefore, the bolt still needs to further in-depth research on new materials. In this paper, the rock model with a negative Poisson’s ratio bolt had been established, the material properties of negative Poisson’s ratio and the working principle of RFPA software were introduced, and RFPA software was used to study the reinforcement effect of negative Poisson's ratio bolt on the rock. The numerical experiment results show that, compared with the positive Poisson's ratio bolt, the negative Poisson's ratio bolt can significantly increase the bearing capacity of anchored rock, enhance the friction between the bolt body and the surrounding rock, and limit the rock movement. The anchored rock with negative Poisson’s ratio bolt can absorb more energy. Negative Poisson's ratio material is one of the future development directions of bolt material.

Dynamic Response and Time-Frequency Characteristic of Dangerous Rocks under the Combined Action of Rock Cavity Weathering and Earthquake

In order to further reveal the failure mode and dynamic response law of dangerous rocks with different degree of weathering in the rock cavity under the action of earthquake and to provide early warning and forecast for steep slope of dangerous rocks in similar earthquake areas, a typical steep slope of dangerous rock in earthquake area of Sichuan, China, was taken as the research object, after detailed geological survey, and according to the chain development law of dangerous rock, the steep slope of dangerous rock before the earthquake was restored. Based on the 3D particle flow software PFC3D, the dangerous rock was divided into 3 modes according to the degree of weathering of the mudstone rock cavity, and the three-dimensional discrete element dangerous rock model under different modes was established. By introducing the horizontal and vertical two-way coupled seismic waves in Wenchuan, Sichuan, in 2008, the failure evolution process of steep slope of dangerous rock under the action of the horizontal and vertical coupled seismic waves was dynamically simulated, which proved the rationality of the simulation. The frequency spectrum of velocity-time history signal of each rock block in the dangerous rock model was analyzed by MATLAB programming, and the time-frequency characteristics of each dangerous rock model under the action of coupled seismic wave were studied. The research results have important scientific guiding significance and practical value for the dynamic stability evaluation and prediction of such steep slope of dangerous rocks under the combined action of rock cavity weathering and earthquake.

Numerical Experiment Research on Failure Characteristics of Anchored Rock With Negative Poisson’s Ratio Bolt

With the continuous increase of mining depth and engineering burying depth, the nonlinear physical and mechanical phenomena exhibited by rock are also more complicated. The load value often exceeds the yield strength of the traditional Poisson's ratio supporting materials, causing the supporting body to fail. Therefore, the bolt still needs to further in-depth research on new materials. In this paper, the rock model with a negative Poisson’s ratio bolt had been established, the material properties of negative Poisson’s ratio and the working principle of RFPA software were introduced, and RFPA software was used to study the reinforcement effect of negative Poisson's ratio bolt on the rock. The numerical experiment results show that, compared with the positive Poisson's ratio bolt, the negative Poisson's ratio bolt can significantly increase the bearing capacity of anchored rock, enhance the friction between the bolt body and the surrounding rock, and limit the rock movement. The anchored rock with negative Poisson’s ratio bolt can absorb more energy. Negative Poisson's ratio material is one of the future development directions of bolt material.