Hasil untuk "Petroleum refining. Petroleum products"

Nayan Adhikary, Anima Nagar

The dual concepts of `universality' and `hypercyclicity' are better understood and studied as `topological transitivity'. In this article we consider transitivity properties of skew products, essentially with non-compact fibers. We study the `Universality Conditions' and `Hypercyclicity Criterion' associated with the dynamical properties of transitivity, weakly mixing and mixing for these skew products.

M. R. Riazi, Dicho Stratiev

Zhujiang Liu, Zhenxue Jiang, Fubin Wei et al.

Deep shale gas has become an important frontier for future shale gas exploration and development. The Wufeng-Longmaxi formations in southern China have undergone complex tectonic and transformation through multi-stage tectonic movements. Deep shale gas enrichment conditions are complex, which greatly restricts the exploration and development of deep shale gas. In this study, based on systematic analysis of basic geological characteristics and gas reservoir characteristics of deep shales, the main factors controlling deep shale gas enrichment in southern China were investigated, and enrichment modes were established. The results show that high-quality shales were developed in the deep-water continental shelf facies, characterized by moderate thermal maturity, high silica content, and abundant organic matter. These characteristics provide a good basis for the formation and enrichment of shale gas. The deep shale gas reservoir is featured by overpressure, high porosity and high gas content. The development and maintenance of high porosity, favorable roof and floor sealing conditions, and weak tectonic activity during uplift stage are the main factors to control deep shale gas enrichment. Based on a comprehensive analysis, the enrichment modes of deep shale gas under three different tectonic patterns were established, namely overpressure enrichment within the basin, overpressure enrichment in the faulted nose or slope of the margin, and overpressure enrichment in the remnant syncline outside the basin. This study provides a reference for exploration and development of deep shale gas in Sichuan Basin and other areas.

Mehdi Razavifar, Timur Yunusov, Aliya Mukhametdinova et al.

Abstract In the last two decades, ultrasonic wave irradiation has gained increased attention from both environmental and economic perspectives in the oil industry. This study investigates the effects of ultrasonic wave irradiation on the components of crude oil and asphaltene deposition in porous media. A series of various experimental methods, including gas chromatography, microscopic imaging, viscosity and average molecular weight measurements, and core flooding, were conducted before and after ultrasonic treatment. The results showed that ultrasonic treatment reduced the number of asphaltene clusters. Additionally, ultrasonic irradiation reduced the average molecular weight of crude oil by 7%. Ultrasonic treatment also decreased core damage by restoring rock permeability. The permeability of the core decreased dramatically from 131 to 27 mD (about 79%) after the injection of crude oil due to asphaltene deposition. However, after ultrasonic treatment, the permeability of the damaged core improved to 82 mD. The findings of this study are valuable for improved oil recovery projects aimed at reducing formation damage near production wells. Graphical abstract

Kyriakos Giagiakos

In this diploma thesis, the mathematical model of a multi-product manufacturing unit will be presented. The unit consists of a set of three conveyors, a robot, a lathe, a milling machine, an assembly machine, and a painting machine. Finally, the connection of the above elements is carried out via one slot buffer. The products can be divided into two distinct sets according to the route they will follow through the machines of the unit. The mathematical models of the individual subsystems of the plant using finite deterministic automata will be presented. The two different routes that the products can follow will be presented. The desired product flow will be presented in the form of desired regular languages. The properties of the desired languages with respect the overall automaton of the system will be investigated. A supervisory architecture will be designed based on the desired regular languages.

Tomoaki Okayama

The Sinc convolution is an approximate formula for indefinite convolutions proposed by Stenger. The formula was derived based on the Sinc indefinite integration formula combined with the single-exponential transformation. Although its efficiency has been confirmed in various fields, several theoretical issues remain unresolved. The first contribution of this study is to resolve those issues by refining the underlying theory of the Sinc convolution. This contribution includes an essential resolution of Stenger's conjecture. The second contribution of this study is to improve the convergence rate by replacing the single-exponential transformation with the double-exponential transformation. Theoretical analysis and numerical experiments confirm that the modified formula achieves superior convergence compared to Stenger's original formula.

Yiqun Li, Hong Wang, Xiangcheng Zheng

We investigate complex boundary conditions of the miscible displacement system in two and three space dimensions with the commonly-used Bear-Scheidegger diffusion-dispersion tensor, which describes, e.g., the porous medium flow processes in petroleum reservoir simulation or groundwater contaminant transport. Specifically, we incorporate the no-flux boundary condition for the Darcy velocity to prove that the general no-flux boundary condition for the transport equation is equivalent to the normal derivative boundary condition of the concentration, based on which we further prove several complex boundary conditions by the Bear-Scheidegger tensor and its derivative. The derived boundary conditions not only provide new insights and distinct properties of the Bear-Scheidegger diffusion-dispersion tensor, but accommodate the coupling and the nonlinearity of the miscible displacement system and the Bear-Scheidegger tensor in deriving the first-order optimality condition of the corresponding optimal control problem for practical application.

Xiaojun Ji, Hao Wang, Wenjian Liu

Milestoning is an accurate and efficient method for rare event kinetics calculations by constructing a continuous-time kinetic network connecting the reactant and product states. However, even with adequate sampling, its accuracy can also be limited by the force fields, which makes it challenging to achieve quantitative agreement with experimental data. To address this issue, we present a refinement approach by minimizing the Kullback-Leibler divergence rate between two Milestoning networks while incorporating experimental thermodynamic (equilibrium constants) and kinetic (rate constants) data as constraints. This approach ensures that the refined kinetic network is minimally perturbed with respect to the original one, while simultaneously satisfying the experimental constraints. The refinement approach is demonstrated using the binding and unbinding dynamics of a series of six small molecule ligands for the model host system, $β$-cyclodextrin.

FANG Dazhi, MA Weijun, YAN Xu et al.

Lithology identification is one of the main application directions of deep learning in oil and gas field development. Artificial intelligence models can effectively improve the efficiency of oil and gas field development and on-site construction. By using wavelet denoising technology, 15 764 logging data from a block are denoised with 7 features to improve the signal-to-noise ratio of logs, and then random forest, XGBoost, and support vector machine models are constructed. The model is used to compare and evaluate the prediction effect of the model by using the precision, recall rate and F1 score. The research results show that the wavelet noise reduction technology can effectively improve the signal-to-noise ratio of the logs and highlight the lithological characteristics. After noise reduction, the XGBoost model performed the best, with test set accuracy, recall, and F1 score all reaching 0.998. The support vector machine adopts the data training after noise reduction, and the prediction effect is improved most obviously, and the total score is increased by 9.2%.

Gaofeng LIU, Huan LIU, Baoan XIAN et al.

From the perspective of geological zone selection for coalbed methane (CBM) development, the evaluation parameters (covering geological conditions and production conditions) of geological sweetspot for CBM development are determined, and the evaluation index system of geological sweetspot for CBM development is established. On this basis, the fuzzy pattern recognition (FPR) model of geological sweetspot for CBM development is built. The model is applied to evaluate four units of No.3 Coal Seam in the Fanzhuang Block, southern Qinshui Basin, China. The evaluation results are consistent with the actual development effect and the existing research results, which verifies the rationality and reliability of the FPR model. The research shows that the proposed FPR model of geological sweetspot for CBM development does not involve parameter weighting which leads to uncertainties in the results of the conventional models such as analytic hierarchy process and multi-level fuzzy synthesis judgment, and features a simple computation without the construction of multi-level judgment matrix. The FPR model provides reliable results to support the efficient development of CBM.

CUI Chuanzhi, YAN Dawei, YAO Tongyu et al.

CO₂ gas channeling time prediction is of great significance for CO₂ gas channeling prevention and enhanced oil recovery. Current studies rarely involve quantitative characterization of the gas channeling time. According to the parameters of the target block reservoir, the crude oil viscosity, reservoir permeability, gas injection rate and injection-production well spacing and other factors impact on the moving rule of the CO₂ drive front is analyzed by the numerical simulation method, then the characterization formula of gas flow time and gas flow influence coefficient considering multiple factors is established, and the accuracy of the formula is verified by comparing with the field practice. The results show that under the condition of constant pressure production, the sweep efficiency decreases with the increase of crude oil viscosity. When the crude oil viscosity is greater than 3 mPa·s, the increase of gas emergence time slows down. When the reservoir permeability increases, the seepage resistance decreases, the displacement front moves faster, and the oil well breaks out earlier. When the gas injection velocity increases, the leading edge movement speed increases and the gas appearance time advances. When the gas injection velocity is 2 500 m³/d, the sweep efficiency is the minimum. When the injection-production well spacing increases, the moving speed of gas front slows down, and the gas emergence time of oil well prolongs. When the injection-production well spacing is larger than 250 m, the well spacing continues to increase, and the sweep efficiency increases slightly.

CHEN Qianqian

The gas test breakthrough of mudstone shale of Taiyuan Formation in Well-MY1 and Well-ZDY2 has proved that the Upper Paleozoic marine-continental transitional shale gas in the South of North China Basin has potential for further tapping resources. Based on the latest data of Well-TX3 and Well-TX4, this paper comprehensively analyzes the shale geochemistry, petrology, reservoir space, physical properties and gas bearing properties of the Taiyuan Formation and Shanxi Formation of the Upper Paleozoic in Tongxu area in the South of North China Basin, the results show that: ① The organic matter of the mud shales of the Taiyuan and Shanxi Formations comes from the vascular plant and belongs to type Ⅲ Kerogen; <i>TOC</i> value is 1.0 %~4.5 % and belongs to good source rock; <i>R</i>_o value is 2.4 %~3.4 % and is in the over mature stage. The mud shale reservoir has higher brittle mineral content, which is favorable for the later fracturing reconstruction. ②The reservoir space is dominated by fractures and micro-fractures, followed by inorganic pores, less developed organic pores and isolated distribution. ③Based on the comparison of the gas test results and shale gas evaluation parameters, the shale gas resource potential of Taiyuan Formation is obviously better than that of Shanxi Formation.

Asuman Güven Aksoy, Francesca Arici, M. Eugenia Celorrio et al.

We study the decomposability of a finite Blaschke product $B$ of degree $2^n$ into $n$ degree-$2$ Blaschke products, examining the connections between Blaschke products, the elliptical range theorem, Poncelet theorem, and the monodromy group. We show that if the numerical range of the compression of the shift operator, $W(S_B)$, with $B$ a Blaschke product of degree $n$, is an ellipse then $B$ can be written as a composition of lower-degree Blaschke products that correspond to a factorization of the integer $n$. We also show that a Blaschke product of degree $2^n$ with an elliptical Blaschke curve has at most $n$ distinct critical values, and we use this to examine the monodromy group associated with a regularized Blaschke product $B$. We prove that if $B$ can be decomposed into $n$ degree-$2$ Blaschke products, then the monodromy group associated with $B$ is the wreath product of $n$ cyclic groups of order $2$. Lastly, we study the group of invariants of a Blaschke product $B$ of order $2^n$ when $B$ is a composition of $n$ Blaschke products of order $2$.

Huili Xing

The notion of covariant-contravariant refinement (CC-refinement, for short) is a generalization of the notions of bisimulation, simulation and refinement. This paper introduces CC-refinement modal $μ$-calculus (CCRML$^μ$) obtained from the modal $μ$-calculus system K$^μ$ by adding CC-refinement quantifiers, establishes an axiom system for CCRML$^μ$ and explores the important properties: soundness, completeness and decidability of this axiom system. The language of CCRML$^μ$ may be considered as a specification language for describing the properties of a system referring to reactive and generative actions. It may be used to formalize some interesting problems in the field of formal methods.

Camilla C. N. de Oliveira, G. Angelkorte, P. Rochedo et al.

Integrated assessment models (IAMs) indicate biomass as an essential energy carrier to reduce GHG emissions in the global energy system. However, few IAMs represent the possibility of co-producing final energy carriers and feedstock. This study fills this gap by developing an integrated analysis of energy, land, and materials. This allows us to evaluate if the production of biofuels in a climate-constrained scenario can co-output biomaterials, being also driven by hydrocarbons/carbohydrates liquid streams made available from the transition to electromobility. The analysis was implemented through the incorporation of a materials module in the Brazilian Land Use and Energy System model. The findings show that bio-based petrochemicals account for 33% of the total petrochemical production in a stringent carbon dioxide mitigation scenario, in 2050. Most of this comes as co-products from facilities that produce advanced fuels as the main product. Moreover, from 2040 mobility electrification leads to the repurpose of ethanol for material production, compensating for the fuel market loss. Finally, the emergence of biorefineries to provide bio-based energy and feedstock reduces petroleum refining utilization in 2050, affecting the production of oil derivatives for energy purposes, and, hence, the GHG emissions associated with their production and combustion.

Sun Lin, Yang Wanyou, Huang Bo et al.

To address the problem of few stimulations for offshore oilfields, research and experiments on combined hydraulic impact fracturing and acidification technology are carried out. Based on the compressible Navier-Stokes equations and continuity equations, a hydraulic impact fracturing pressure wave model is established. A high-precision simulation software is compiled. The acid-resistant joint tool for use in &#248;244.5 and &#248;177.8 mm casing holes in the offshore oil field is optimized. The impact plate and the impact chamber are optimized to improve the stability, safety and acid resistance of the tool. The safety checks of the casing and the operating string are carried out, and the suitable peak pressure control range is given. The on-site cuttings dissolution rate by the developed strong dissolution acid liquid system can reach 42.07%～43.13%. The permeability in the dynamic displacement test was 1.57～1.76 times that before the displacement. The technical verification experiment carried out verified the rock breaking performance, the software simulation accuracy, and the performance of the acid. The research results can further strengthen the stimulation performance of technology in offshore oilfields, and improve the accuracy and safety of technical simulation, which has certain reference significance for the development of similar oilfields.

Ilia Beloglazov, Valentin Morenov, Ekaterina Leusheva

Today, the issues related to solving the problem of finding an effective distribution of oil flows through the system of oil pipelines in order to reduce the total energy consumption are relevant. The solution to this problem is connected with selection of rational pumping modes for various technological sections of oil pipelines using modern methods of mathematical programming or new techniques for improving the energy and transport characteristics of oil.Reducing energy consumption during pumping of crude through oil trunk pipelines can be achieved by various methods. Numerous investigations in this direction are mainly carried out to save energy on separate single-line pipelines. However, due to the development of the network of trunk oil pipelines in the world over the past decades, the issues of energy efficient management of oil flows throughout the entire oil pipeline system of oil and gas enterprises become urgent.This paper analyses parameters for pipeline transport of high-viscosity and heavy oils. The article proposes a method for assessing the rheological properties of oil for further planning of pumping taking into account the preservation of oil quality and an increase in energy and transport characteristics. The proposed solutions and tasks for predicting changes in the viscosity-temperature characteristics of the flow for blends of different oil types are especially relevant in the current conditions of an increase in the share of oil production with complex rheological characteristics. Results of the presented investigations may be used for planning the measures of efficient transportation of high-viscosity and heavy oils.

Mingshui SONG, Huimin LIU, Yong WANG et al.

Based on formation testing data of more than 40 wells with industrial oil flow, systematic observation of 1 010.26 m long cores taken from 4 wells and test data of over 10 000 core samples combining with drilling and pilot fracturing data of multiple wells, the geological characteristics of the upper submember of the Sha 4 Member to the lower submember of the Sha 3 Member of Paleogene (Es4s-Es3x) in the Jiyang Depression were investigated to find out factors controlling the enrichment of shale oil and the accumulation model of shale oil, and a comprehensive evaluation method for shale oil sweet spots was established. It is found through the study that the target shale layer is characterized by strong heterogeneity, weak diagenesis, low thermal evolution and high content of clay and carbonate minerals. Shale lithofacies, microcrack, thin interlayer and abnormal pressure are the main factors affecting enrichment and stable production of shale oil, the organic rich laminar shale has the best storage and oil-bearing capacity, microcrack network system improve the storage capacity and permeability of the shale, the thin interlayer is the main flow channel for stable shale oil production, and the abnormal high pressure layer is rich in free state shale oil and high in oil content. The shale oil layers in the target section were divided into three types: matrix, interlayer and fracture ones. According to the occurrence state and exploration practice of shale oil at home and abroad, it is concluded that the interlayer shale oil is the most profitable type at present. The selection parameters for the different types of shale oil were determined, and accordingly the favorable areas were pointed out by comprehensive evaluation of multiple factors. Vertical wells in the interlayer shale oil reservoir, such as Fan 159, Fan 143 and GX 26, were stimulated by volume fracturing and high conductivity channel fracturing jointly. After fracturing, they had a daily oil production of over 6 t, up to 44 t, and stable productivity. Shale oil is expected to become an important replacement energy resource in the Jiyang Depression. Key words: shale oil, enrichment elements, enrichment model, shale oil sweet spot, lithofacies, microcrack, thin interlayer, abnormal pressure, Jiyang Depression

LI Yuelin, XU Sihui, WANG Lijuan et al.

As the actual logging situation is complex, some resistivity curves of mud invasion wells only contain resistivity curve while drilling. And as the mud invasion is not complete during the measurement, conventional mud invasion correction methods can not be applied to the mud invasion correction in this kind of wells. In order to solve this problem, a new correction method is proposed, that is, the water saturation are corrected directly with the relation between water saturation before and after mud invasion according to the improved volume model. The water saturation measured by RPM is corrected directly to effectively avoid the inapplicability of resistivity logging data. Then the correction model is applied to the interpretation of logging data, and it is found that the interpretation conclusion is consistent with the actual outputs. The interpretation results of mud invasion correction by resistivity curves while drilling is corrected, which verifies the feasibility of the correction method. This method provides a new idea for the mud invasion correction.