Key parameters and evaluation methods for large-scale production of lacustrine shale oil

Expansion of shale oil production to commercial scale in Colorado, USA required an investigation of potential adverse health effects that could result from exposure to raw shale oil, intermediate streams and final products. Comparison of Scottish shale oil products, operations, occupational exposures and adverse health effects with shale oil products and operations planned for Colorado showed the importance of severe hydro‐treating of raw shale oil to remove biologically active molecules (believed to be mainly aromatic heterocyclics) that apparently were responsible for most of the adverse health effects experienced by Scottish shale oil workers, neighbors and users.

Controlling factors for oil production in continental shales: A case study of Cretaceous Qingshankou Formation in Songliao Basin

Theories, technologies and practices of lacustrine shale oil exploration and development: A case study of Paleogene Kongdian Formation in Cangdong sag, Bohai Bay Basin, China

The success of shale oil exploration and production is highly dependent on the heterogeneous nature of the reservoir pore structure. Despite this, there remains limited research on the heterogeneity characteristics of pores at different scales in lacustrine shale oil reservoirs and the factors that impact them. This study aims to quantitatively characterize the multi-scale pore heterogeneity differences of the lacustrine shale found in the Funing Formation in Gaoyou Sag. Additionally, the study seeks to clarify the impact of the total organic carbon (TOC) and lithofacies type on pore structure heterogeneity. To achieve this, nitrogen adsorption, scanning electronic microscope (SEM), mercury intrusion porosimetry (MIP), and other experimental means were adopted in combination with the fractal dimension model of FHH and capillary. The results show that the predominant lithofacies of the Funing Formation shale samples are mixed shale (MS) and siliceous shale (SS), with a limited presence of calcareous shale (CS). The micro-pores of lacustrine shale are dominated by inorganic mineral pores and fewer organic pores. Intragranular pores and clay mineral pores are two types of inorganic mineral pores that are widely found. Small pores (pore diameter < 50 nm) make up 89% of the pore volume (PV) and 99% of the specific surface area (SSA). The fractal dimensions D1, D2, and D3 were calculated to characterize the roughness of the pore surface, the structural complexity of small pores, and the structural complexity of large pores (pore diameter > 50 nm), respectively. The increase in the total organic carbon (TOC) resulted in a decrease in the D1, D2, PV, and SSA, while connectivity showed a slight improvement. The fractal dimension of shale across all lithofacies followed the pattern: D3 > D2 > D1. The pore structure is more complex than the pore surface, and the large pores showed a greater heterogeneity than the small pores. Among the three lithofacies, CS had the largest PV, SSA, D1, and D2, indicating the development of a more complex pore structure network. This expands the space required for shale oil occurrence. However, the connectivity of the CS lithofacies is the lowest among the three, which hinders shale oil production. Although the PV of SS is slightly lower than that of CS, its average pore diameter (AVE PD) and connectivity are significantly advantageous, making SS an ideal shale reservoir. This study provides an important reference for the reservoir evaluation required to better develop lacustrine shale oil around the world.

Topochemical heat in-situ pyrolysis of oil shale is achieved by injecting high temperature nitrogen to promote oil shale pyrolysis and release heat, and then injecting air to trigger oil shale combustion in the early stage of oil shale pyrolysis, and then by injecting normal temperature air continuously to promote local oxidation of oil shale in the later stage. In order to verify the oil and gas recovery by topochemical heat method, Jilin University has chosen Fuyu City, Jilin Province, to carry out pilot project of oil shale in-situ pyrolysis by topochemical heat method. Besides, in order to infer the spontaneity, feasibility and difficulty of continuous pyrolysis of oil shale based on topochemical heat, this paper, the mechanism of solid-state pyrolysis and the thermodynamic analysis of transition state of oil shale in Fuyu area are discussed. Because the second stage of oil shale pyrolysis is the main stage of oil production. Therefore, the characteristics of Gibbs free energy, free enthalpy and free entropy of transition state in the main oil production stage of oil shale pyrolysis are obtained by calculation. The results show that in situ pyrolysis of oil shale topochemical heat can be carried out spontaneously and continuously, and the release characteristics of volatiles during pyrolysis of oil shale are described.

Depletion of conventional oil fields contributes to the development of hard-to-recover raw materials. This raw material is shale oil. The Russian Federation ranks third in the world's shale oil reserves. However, the high cost, significant environmental risks, low productivity of existing mining methods are a constraining factor for the development of this type of raw material. The most common oil production methods are gas injection, water based chemical injection, thermal and biological methods. The article provides recommendations for choosing a method for shale oil production with examples of well treatment based on the experience of the authors. previously proposed methods of oil production using thermobarochemical treatment of the bottomhole zone of the well are described. A method of shale oil production based on the use of powder charges providing flameless smokeless combustion in the case of directional drilling is proposed. This method provides for a longer maintenance of the temperature, which allows to open cracks in the oil shale formation and preserve light fractions of hydrocarbons.

An investigation of long range reliance on shale oil and shale gas production in the U.S. market

Oil shale mining and processing in northeast Estonia have brought about several ecological problems. The mined oil shale is used as fuel in power stations and in processing plants producing crude oil and about 40 manufactured articles. Pollutants emitted from oil shale processing and chemical plants include SO2, CO, NO x , oil shale fly ash, and organic compounds in which aromatic and aliphatic hydrocarbons, phenols, formaldehyde, etc., are represented. Pollution has caused changes in the condition of the forest ecosystem and the chemical character of soil and ground water. The condition of coniferous forest sites was investigated in 1995–1998. Because of the high concentration of alkaline fly ash in the air, the pH of rain water is somewhat elevated (pH = 7.0–7.1) and exceeds the level regarded as normal for rain water. The analysis of the soil samples showed that the concentrations of Ca, Mg and K, which dominate in the solid fraction of the pollutant mixture, are high, being respectively 18, 14, and 4 times as high as the control. The increases in the concentrations of K, Mg, Cu, Pb, and Ni in stemwood reflect increases in the regional oil shale fly ash deposition. Conifers influenced by high levels of air pollution emitted from the oil shale industry are characterized by retarded growth of needles and shoots and radial growth as a result of disturbances in their mineral nutrition and imbalance in their mineral composition.

The inconsistency of shale oil and gas production decline prediction methods leads to the inconsistency of shale oil and gas production decline curve prediction. Aiming at this problem, this paper introduces five commonly used shale oil and gas production decline curve models: typical curve model based on ARPS model, modified hyperbolic decline model, power index model, mixed typical curve model and Duong model. The prediction methods of uncertainty typical curve model and certainty typical curve model are studied. The results show that the production history of multistage fractured horizontal wells is not long enough, and it is difficult to verify the production decline in the later stage, so it is suggested to use hyperbolic decline model or modified hyperbolic decline model. Aiming at the blocks with production data, a prediction method of uncertain shale oil and gas production decline based on production performance data is proposed. The results are in good agreement with the actual production data, and can be used in oilfield production allocation. Due to the characteristics of shale reservoir such as nanometer pore size, nadasi permeability, strong heterogeneity and high fracturing strength of long horizontal wells, the output of shale oil and gas wells varies greatly. The typical production decline curve obtained by deterministic method has certain risk.

A 40 degrees A.P.I. crude shale oil has been produced from the Green River Formation in the Piceance Creek Basin of Colorado by injection of hot natural gas at a controlled temperature. The quality of the shale oil differs very markedly from the customary shale oil from the same formation produced in a high temperature retort. The characteristics of the oil fractions have now been determined. These include distillation analyses, viscosity, and pour point determination. Kinetic data on the production of the shale oil under the conditions used in the field, but carried out on a small scale in the laboratory will be presented. A possible mechanism for the production of this oil, as well as a mechanism for the production of shale oil by more usual high temperature methods will be presented. TEXT Various methods for the production of shale oil by in situ techniques are being investigated in the United States. The method with which this paper is concerned involves the use of hot natural gas as the energy conveying medium to convert the kerogen in the oil shale to a petroleum like liquid. The basic concept, which was developed by the late J.L. Dougan of Equity Oil Company and tested in the Fuels Engineering Department laboratories at the University of Utah and subsequently field tested in the Piceance Creek Basin of Colorado, is basically a low temperature conversion and distillation process. Natural gas is heated to a temperature below its thermal decomposition temperature and injected through an insulated pipe into the Green River Oil Shale formation where it loses its heat rapidly to the oil shale, gradually raising the temperature of the shale toward that of the injected gas. The kerogen is converted to bitumen and finally to a low pour point, high gravity crude oil. Since the temperature of the natural gas is below that for thermal decomposition of the mineral carbonates in the oil shale, little CO2 is produced. The natural gas is compatible with the oil, being soluble in it; this aids in the penetration of the formation by the natural gas and in the heat transfer. Since the heating gas is completely free from oxygen, no oxidation induced polymerization of the oil occurs. Prior to the field experiment, oil shale cores from the Piceance Creek Basin were heated in a natural gas stream under two conditions. Some experiments were run at a gas pressure of 300 lb/sq. inch.

Investigating pilot test of oil shale pyrolysis and oil and gas upgrading by water vapor injection

Influences of controlled microwave field irradiation on occurrence space and state of shale oil: Implications for shale oil production

Enrichment factors of movable hydrocarbons in lacustrine shale oil and exploration potential of shale oil in Gulong Sag, Songliao Basin, NE China

Heating development has become the main development mode of medium- to low-maturity shale oil. In this study, the thermodynamic mathematical models of flow and heating development of organic matter, inorganic matter, hydraulic fracture, and natural fracture are established based on the embedded discrete fracture model (EDFM). A model for calculating the apparent permeability is established based on the fractal theory considering the effect of adsorption and slippage of fluid in shale pores. The mathematical model is solved by the finite volume method. The results show that improving formation temperature can increase the shale oil production. When the temperature increases from 338 K to 500 K, the cumulative production of shale oil can increase by 40.34%. The more natural fractures are, the greater the cumulative production of shale oil is. As the half-length of hydraulic fracture increases, the cumulative production of shale oil increases. When there is greater thermal conductivity and a decrease in the heat capacity of the matrix, the formation area affected by the thermal effect is enlarged and the cumulative oil production increases. There is a negative correlation between the shale oil production and the proportion of pore volume of organic matter. Through the study of the influencing factors of shale oil heating development, characteristics of shale oil production under different fracture and matrix parameters are clarified, and the optimal parameters under different influencing factors are obtained and a significant theoretical basis for shale oil heating development is achieved.

Evaluating microdistribution of adsorbed and free oil in a lacustrine shale using nuclear magnetic resonance: A theoretical and experimental study