Hasil untuk "Oils, fats, and waxes"

Junliang Li, Lili Ji, Wenbin Jiang et al.

Abstract Multiscale pore-slit structures, non-linear flow and complex lithofacies of continental shale in Dongying Sag present significant challenges for reservoir evaluation and sweet spots identification. This study establishes a comprehensive analytical framework through integrated physical experiments and high-resolution imaging to characterize pore-slit structures and flow dynamics across various lithofacies. Firstly, a novel PSD (pore size distribution) splicing technique is developed by combining multiscale feature extraction and a transformed method, seamlessly uniting nitrogen adsorption data with SEM (scanning electron microscopy) image analysis. Compared with traditional methods, this advanced technique provides a more comprehensive representation of shale pore size distribution and structural characteristics. Three permeability indexes, including the non-Darcy index (K non−D ), anisotropy index (K a ), and slit index (K f ), are proposed to quantify flow behavior based on the cubic-block and matrix permeability experiments. These innovative indexes allow us to explore the complex non-linear flow behaviors, the anisotropic flow properties and pore-slit crossflow characteristics of shale. Comparative analysis reveals distinct pore structure and flow characteristics among different lithofacies: clay-rich shale exhibits high porosity and matrix permeability, while carbonate-rich shale demonstrates stronger nonlinear flow capacity and anisotropic permeability. Finally, the intrinsic relationship between mineral composition, pore structure, and complex flow has been investigated, and the identification charts for porosity and permeability have been established. These findings provide valuable tools for enhanced reservoir evaluation and sweet spot identification in the continental shale formations of Dongying Sag.

WANG Shoujun

Microsphere flooding technology has attracted much attention because it effectively blocks high-permeability channels and improves reservoir flow performance. Based on core flooding experiments and rheological experiments， the dispersion， oil displacement performance， long-term stability， and action mechanism of microspheres in sewage at different concentrations and pH values from Shengli Oilfield were systematically analyzed. The results show that as the concentration of sewage from Shengli Oilfield increases from 0 to 50%， the average particle size of the microspheres increases from 1.2 µm to 2.0 µm， indicating a significant deterioration in dispersion. Under different pH conditions， the average particle size of the microspheres is 2.2 µm in the sewage with a pH of 4， while it decreases to 1.3 µm， showing better dispersion in the sewage with a pH of 9. The core flooding experiments indicate that the oil displacement efficiency of the microspheres is the highest， reaching 50.3%， in sewage with high organic content from Shengli Oilfield. The long-term stability of the microspheres is poor in the sewage at a concentration of 30%， with the average particle size increasing to 2.1 µm after 28 days. The rheological experiments show that microsphere suspensions exhibit shear thickening properties， with a shear stress of 9.1 Pa at a shear rate of 1 000 s-¹. The mechanism analysis reveals that the microspheres interact with impurities and suspended particles in the sewage through electrostatic adsorption， physical adsorption， and chemical adsorption， significantly affecting their dispersion and oil displacement effects.

DING Jiaqian, LIU Haitao, SUN Jianmeng et al.

Accurate evaluation of cementing quality plays a crucial role in ensuring the safety and efficiency of oil and gas field development. To address the limitations of traditional methods in dual-casing wells, this study proposes a cementing quality evaluation method for dual-casing wells based on continuous wavelet transform (CWT). This paper systematically elaborates on the basic theory of CWT, uses the Morlet wavelet as the basis function to perform time-frequency transformation and in-depth analysis on actual well logging data, and extracts multi-dimensional characteristic parameters such as first arrival time and amplitude. It clarifies the thresholds and judgment logic for characteristic parameters, establishes a multi-scale time-frequency analysis framework and quantitative identification criteria for the cementation state at the multi-interfaces (casing-cement sheath-formation), and conducts comparative verification by combining numerical simulations and logging data from single-casing and dual-casing wells. The research results show that: ① It successfully distinguishes different states, including good cementation at all interfaces and poor cementation at 1 to 4 interfaces, and identifies the differences in time-frequency characteristics under different cementation states. For example, when cementation is good, obvious formation waves exist in the frequency band of 8～12 kHz; when cementation at the first interface is poor, the energy in the time window of 0.30～0.45 ms and frequency band of 15～30 kHz exceeds the threshold of 500. ② In the application of the 35～220 m interval of Well A, it is found that the proportion of poor cementation at the second and third interfaces is significantly higher than that of other interfaces. Poor cementation at the third interface occurs concentratedly in the 110～150 m interval; continuous poor cementation at the second interface appears in the 65～70 m and 72～82 m intervals; and continuous poor cementation at the fourth interface is observed in the 195～220 m interval. ③ Compared with traditional methods, the adaptability of the proposed method to complex formations is significantly improved. It can accurately distinguish the cementation quality of the second and third interfaces, which are difficult to judge by traditional methods, and solves the problems of reduced resolution and insufficient collaborative evaluation of multi-interfaces in traditional methods. ④ Through the comparison between simulated data and actual data, the reliability of the quantitative relationship model is verified, and the evaluation results of poor cementation at the four interfaces of dual-casing wells are in good agreement with those of single-casing wells. It is concluded that this quantitative evaluation method based on CWT provides an effective new approach for cementing quality evaluation of dual-casing wells, significantly improves the accuracy and reliability of evaluation, and promotes the development of related evaluation technologies in oil and gas exploration and development.

Qin Saibo, Yi Xianzhong, Zhang Xuwen et al.

As the exploration and exploitation of petroleum gradually shift from land to ocean, from shallow sea to deep sea and then to ultra-deep sea, the conventional onshore iron roughnecks are unable to work directly on deepwater offshore platforms. To address this issue, a new type of iron roughneck arm structure supporting the seabed drilling system was proposed. The numerical simulation method was used for safety analysis on the strength, fatigue strength, stiffness, stability and vibration resistance of the iron roughneck arm structure. According to the research results, when the structure of the iron roughneck arm used in seabed drilling is in a dangerous posture(extending 1.8 m), the maximum von Mises stress is 195.45 MPa(less than the allowable stress [σ]=320 MPa), and the fatigue strength safety factor n=4.63(greater than the allowable safety factor [n]=2.0). The total flexural rigidity and the flexural rigidity in the x, y, and z directions of the iron roughneck arm structure are 1.11×10¹⁰, 1.62×10¹², 2.43×10¹³ and 7.34×10¹⁰ N·m², respectively, meeting the rigidity requirements of the iron roughneck arm structure. The critical buckling load of the iron roughneck arm structure P_cr=915.80 kN, which is 45.79 times the actual load, meeting the stability requirements of the structure. There is a 68.23% probability that the maximum von Mises stress of the iron roughneck arm structure does not exceed 179.77 MPa under random vibration excitation, meeting the material strength safety requirements. The research results have verified the safety and reliability of the designed structure of the new type of iron roughneck arm used in seabed drilling, and provide some reference for the structural design of it.

Jinmin SONG, Shugen LIU, Zhiwu LI et al.

The depositional facies types of the fourth member of the Middle Triassic Leokoupo Formation (Lei-4 Member) in western Sichuan Basin are examined through the methods of sedimentology, lithology and analysis of well-logging data, as well as the special lithofacies indicators such as microbialite, gypsum-salt rock and tempestites, using the data of about 400 wells and 11 outcrop sections. The distribution and evolution and its hydrocarbon geological significances of the bay facies have been discussed. The Lei-4 Member in western Sichuan Basin has an ocean–bay–flat depositional model, with the presence of evaporated tidal flat, restricted tidal flat and paleo-bay facies from east to west. The subfacies such as bay margin, subtidal bay and bay slope are recognized within the paleo-bay, with microbial reef and grain bank microfacies in the bay margin, microbial flat, deep-water spongy reef and hydrostatic mudstone microfacies in the subtidal bay, and tempestites and collapsed deposits in the upper bay slope. The bay boundary covered the Guangyuan-Zitong-Dujiangyan area in the period of the first submember of the Lei-4 Member (Lei-4-1) with falling sea level, regressed westward into the Shangsi-Jiangyou-Dujiangyan area in the period of Lei-4-2, and expanded to the Shangsi-Zitong-Langzhong- Wusheng-Yanting-Chengdu area in the northern part of central Sichuan Basin in the period of Lei-4-3 along with a small-scale transgression. The topographic pattern of “one high and two lows” is confirmed in the Lei-4 Member, corresponding to a configuration of source rocks and reservoir rocks alternated horizontally and superimposed vertically. Two efficient source-reservoir configuration models, i.e. side source & side reservoir, and self-generating & self-storing, are available with the microbial reef and grain bank reservoirs at the bay margin and the high-quality source rocks within the sags on both sides of the bay. The research findings will inevitably open up a new situation for the hydrocarbon exploration in the Leikoupo Formation.

XU Ning, CHEN Zhewei, XU Wanchen et al.

Energy storage volume fracturing is a pivotal early development technique for shale reservoirs, designed to supplement reservoir energy preemptively and significantly boost single well production. A method for predicting the maximum cumulative oil production during the development stage of energy storage fracturing is proposed, based on the mechanisms of imbibition and displacement coupled with the statistical analysis of actual production data. The results demonstrate that following a 30% flowback ratio, the cumulative oil production from energy storage fracturing exhibits a strong linear relationship with the logarithm of the flowback ratio. This relationship can predict the maximum cumulative oil production of a single well after fracturing. Validated by actual production data from other shale reservoirs, this method proves to be more accurate and universal than the decline curve analysis method. It encompasses a comprehensive evaluation of subjective and objective factors such as reservoir conditions, fracturing scale and technology, production system design, and drainage efficiency. Additionally, the method facilitates the determination of the liquid-to-oil ratio and the reasonable flowback rate. By controlling the average rate of discharge and production within the range of 6~8 m³/（d·km）, which aligns with the rates of oil drainage and imbibition, higher oil recovery and a lower liquid-to-oil ratio are achieved. This prediction method for maximum recoverable oil post-single well fracturing provides a basis for the economic benefit evaluation, production system optimization, and fracturing cost control of energy storage fracturing. It holds significant guiding importance for geological-engineering integration, well spacing optimization, and fracturing design.

Gongcheng ZHANG, Dianjun TONG, Kai CHEN et al.

The Bohai Bay Basin, as a super oil-rich basin in the world, is characterized by cyclic evolution and complex regional tectonic stress field, and its lifecycle tectonic evolution controls the formation of regional source rocks. The main pre-Cenozoic stratigraphic system and lithological distribution are determined through geological mapping, and the dynamics of the pre-Cenozoic geotectonic evolution of the Bohai Bay Basin are investigated systematically using the newly acquired high-quality seismic data and the latest exploration results in the study area. The North China Craton where the Bohai Bay Basin is located in rests at the intersection of three tectonic domains: the Paleo-Asian Ocean, the Tethys Ocean, and the Pacific Ocean. It has experienced the alternation and superposition of tectonic cycles of different periods, directions and natures, and experienced five stages of the tectonic evolution and sedimentary building, i.e. Middle–Late Proterozoic continental rift trough, Early Paleozoic marginal-craton depression carbonate building, Late Paleozoic marine–continental transitional intracraton depression, Mesozoic intracontinental strike-slip–extensional tectonics, and Cenozoic intracontinental rifting. The cyclic evolution of the basin, especially the multi-stage compression, strike-slip and extensional tectonics processes in the Hercynian, Indosinian, Yanshan and Himalayan since the Late Paleozoic, controlled the development, reconstruction and preservation of several sets of high-quality source rocks, represented by the Late Paleozoic Carboniferous–Permian coal-measure source rocks and the Paleogene world-class extra-high-quality lacustrine source rocks, which provided an important guarantee for the hydrocarbon accumulation in the super oil-rich basin.

Bulat Galimzyanov, Maria Doronina, Anatolii Mokshin

The viscosity of crude oil is an important physical property that largely determines the fluidity of oil and its ability to seep through porous media such as geological rock. Predicting crude oil viscosity requires the development of reliable models that can reproduce viscosity over a wide range of temperatures and pressures. Such viscosity models must operate with a set of physical characteristics that are sufficient to describe the viscosity of an extremely complex multi-phase and multi-component system such as crude oil. The present work considers empirical data on the temperature dependence of the viscosity of crude oil samples from various fields in Russia, China, Saudi Arabia, Nigeria, Kuwait and the North Sea. For the first time, within the reduced temperature concept and using the universal scaling viscosity model, the viscosity of crude oil can be accurately determined over a wide temperature range: from low temperatures corresponding to the amorphous state to relatively high temperatures, at which all oil fractions appear as melts. A novel methodology for determining the glass transition temperature and the activation energy of viscous flow of crude oil is proposed. A relationship between the parameters of the universal scaling model for viscosity, the API gravity, the fragility index, the glass transition temperature and the activation energy of viscous has been established for the first time. It is shown that the accuracy of the results of the universal scaling model significantly exceeds the accuracy of known empirical equations, including those developed directly to describe the viscosity of petroleum products.

Tang Ruihuan

As the number of ultra-deep and long horizontal wells of unconventional oil and gas continuously increase,the reservoir reconstruction technology for oil and gas exploitation is also continuing to follow up,thus promoting the development of fracturing equipment in the direction of high power,high load,continuous operation and intelligence.Sichuan-Chongqing block is the main battlefield of shale gas development in the “14th Five-Year Plan” in China.On the basis of introducing the operation status of traditional fracturing equipment,this paper analyzed its shortcomings in shale gas fracturing in Sichuan-Chongqing area,pointed out that fracturing equipment would develop in the direction of electric fracturing equipment and turbine fracturing equipment,conducted outlook on application of fault state monitoring and diagnosis system of fracturing set,fracturing energy storage(power transformation)system technology and low-voltage integrated Internet of Things(IOT)system technology in fracturing equipment,and further pointed out the development direction of fracturing technology and equipment in China,i.e.,development in the direction of environmental optimization,light weight and automation.The conclusions provide reference for the efficient development of shale gas and the field application and optimization of fracturing equipment in Sichuan-Chongqing area in China.

Alexey V. Calabourdin, Konstantin A. Aksenov

We develop an online learning MCMC approach applicable for hierarchical bayesian models and GLMS. We also develop a fat-tailed LTV model that generalizes over several kinds of fat and thin tails. We demonstrate both developments on commercial LTV data from a large mobile app.

ZHAO Lan

The average porosity and permeability of sandstone of Lower Shihezi Formation of Permian system in Shilijiahan area of Hangjinqi area are of 8.3 % and 0.89×10^-3 μm² respectively, causing the reservior to be a typical tight sandstone reservoir. Meanwhile, the microfractures play an important role in improving the physical properties of tight sandstone reservoir. Therefore, the researches of the reservoir in this area focus on the microfractures. By the observation of the microscopic thin section, and combined with the mercury injection, core physical properties and structural characteristics, the types and genesis, formation stages, control factors and the influence of micro fractures on physical properties in this area have been studied. The results show that the tight sandstone of Lower Shihezi Formation in the study area can be divided into intragranular fracture, grain edge fracture and grain penetrating fracture according to the contact relationship of strata, and can be divided into unfilled fracture, incomplete filled fracture and complete filled fracture according to the filling degree. According to the genetic analysis, there are at least three stages of micro fractures in the study area. Their development degree are controlled by the combination of internal factors （sandstone particle size, rock debris composition, rock debris and interstitial content, contact relationship between particles, etc.） and external factors （tectonic stress）. The microfractures mainly affect the permeability of the reservoir. The multi-factor influence is a basic feature of micro fractured tight reservoir. The average throat radius plays a major role in controlling the permeability of the reservoir.

Gao Junhong, Fu Biwei, Dong Zongzheng

In order to improve the application results of hydraulic radial drilling technology in hydrate exploitation and reservoir stimulation,numerical simulation method was used to study the drilling performance of self-propelled nozzle,which is the core component of hydraulic radial drilling.The drilling performances of three commonly used self-propelled nozzles were compared and analyzed in terms of the propulsion performance and rock-breaking effect.The results show that the jet core length of the straight-rotary mixing jet nozzle is 1.18 times that of the rotary jet nozzle,which enables to eliminate the low-speed zone in the center of the rotary jet.And the tangential velocity and radial velocity of the jet are larger,which enable better shear rock breaking effect.The straight-rotary mixing jet nozzle has obviously larger effective rock-breaking area than that of the straight jet nozzle and it helps to produce larger holes.In addition,there is an optimal operating pressure range for the best drilling performance of the straight-rotary mixing jet nozzle.The study shows that the straight-rotary mixing jet nozzle has good drilling performance with the rock-breaking advantages of both straight jet and rotary jet.The results provide reference for efficient exploitation of marine natural gas hydrate and reservoir stimulation.

DENG Jiasheng, WANG Ziyi, HE Wangda et al.

During the reaction between CO₂ and rocks, there is a synergistic/coupling effect among minerals because the rocks contain quartz, potassium feldspar, albite and other components, which promotes or inhibits the reaction process to a certain extent. The chlorite is an important clay mineral of sedimentary rocks. In order to clarify the chemical behavior and change process of the chlorite in the CO₂ aqueous solution, the state of chlorite reacting with CO₂ respectively for 7 and 30 days at 10 MPa and 60 ℃ are systematically evaluated by means of XRD（X-Ray Diffraction）, XRF（X-Ray Fluorescence）, ICP（Inductively Coupled Plasma）, and SEM（Scanning Electron Microscopy）, focusing on the comparison of the change of the solid elements, the crystal structure and the ion concentration in the reaction solution before and after chlorite powder reaction. Combined with the structural characteristics of chlorite, the mechanism of chlorite change is clarified. The results show that the concentrations of Ca²⁺, Mg²⁺ and Al³⁺ in the liquid phase firstly increase and then decrease after the reaction of the chlorite with CO₂. The concentration of Si⁴⁺ firstly increases and then is stabilized. The crystal planes corresponding to chlorite d（002） and d （004） peaks in the solid phase are destroyed after the reaction, and the mass ratio of Si and Al in the solid element increase from 4.82 to 5.39. Under the acidic conditions, hydroxyl groups in brucite flakes are easier to combine with H⁺ and release cations such as Fe²⁺, Mg²⁺, Al³⁺, etc. Because the brucite octahedron is more prone to ion exchange than silica tetrahedron and alumina octahedron, Mg, Al, Fe and other elements in brucite flakes are dissolved before Si and Al in silica tetrahedron and alumina octahedron.

Pierre Mendy, Babacar M. Ndiaye, Diaraf Seck et al.

By considering the Wade Formula, we propose a model to study the evolution of the oil price per barrel. Our model shows that the policy of diversification of the energy is to be supported. This model is proposed to see how it is possible to control parameters so that the oil price should decrease.

Sebastian Dehe, Steffen Hardt

Fluidic interfaces disintegrate under sufficiently strong electric fields, leading to electrohydrodynamic (EHD) tip streaming. Taylor cones, which emit charged droplets from the tip of a conical cusp, are among the most prominent and well-studied examples of EHD instabilities. In liquid-liquid systems, more complex interface deformation modes than simple Taylor cones can be observed, with the interface being pushed away from the electrode, and additional cone structures emerging from the rim of the dimple. In this article, we investigate the mechanisms behind these deformation modes experimentally and numerically, and demonstrate that the presence of droplets triggers the dimple at the interface. In order to characterize the underlying processes, we replace the pin electrode by a hollow metallic needle with a prescribed electrolyte volume flow. The submerged electrospray introduces droplets of an aqueous KCl solution with varying ion concentrations into silicone oils with varying viscosities. By measuring the corresponding electric current and by optical investigation of the interface deformation, we study the system response to variations of the ionic concentration, viscosity, applied voltage as well as flow rate. In addition to the experiments, we use a finite element solver and compute the charge transport due to the droplets in the oil phase. Further, we compute the electric potential distribution, flow field and interface deformation. After calibration of our model with particle tracking velocimetry data of the flow inside the oil phase, we reproduce the experimentally observed dimple at the liquid-liquid interface. In summary, this work highlights the importance of charged droplets for the complex dynamic modes observed when a liquid-liquid interface is exposed to a local electric field.

Andrés C. Rodríguez, Stefano D'Aronco, Konrad Schindler et al.

Accurate mapping of oil palm is important for understanding its past and future impact on the environment. We propose to map and count oil palms by estimating tree densities per pixel for large-scale analysis. This allows for fine-grained analysis, for example regarding different planting patterns. To that end, we propose a new, active deep learning method to estimate oil palm density at large scale from Sentinel-2 satellite images, and apply it to generate complete maps for Malaysia and Indonesia. What makes the regression of oil palm density challenging is the need for representative reference data that covers all relevant geographical conditions across a large territory. Specifically for density estimation, generating reference data involves counting individual trees. To keep the associated labelling effort low we propose an active learning (AL) approach that automatically chooses the most relevant samples to be labelled. Our method relies on estimates of the epistemic model uncertainty and of the diversity among samples, making it possible to retrieve an entire batch of relevant samples in a single iteration. Moreover, our algorithm has linear computational complexity and is easily parallelisable to cover large areas. We use our method to compute the first oil palm density map with $10\,$m Ground Sampling Distance (GSD) , for all of Indonesia and Malaysia and for two different years, 2017 and 2019. The maps have a mean absolute error of $\pm$7.3 trees/$ha$, estimated from an independent validation set. We also analyse density variations between different states within a country and compare them to official estimates. According to our estimates there are, in total, $>1.2$ billion oil palms in Indonesia covering $>$15 million $ha$, and $>0.5$ billion oil palms in Malaysia covering $>6$ million $ha$.

Alyssa M. Tate, Brittany Hundman, J. Heile

ABSTRACT Leather has been produced by a variety of methods throughout human history, providing researchers unique insight into multiple facets of social and economic life in the past. Archaeologically recovered leather is often fragile and poorly preserved, leading to the use of various conservation and restoration efforts that may include the application of fats, oils, or waxes. Such additives introduce exogenous carbon to the leather, contaminating the specimen. These contaminants, in addition to those accumulated during interment, must be removed through chemical pretreatment prior to radiocarbon (14C) dating to ensure accurate dating. DirectAMS utilizes organic solvents, acid-base-acid (ABA) and gelatinization for all leather samples. Collagen yield from leather samples is variable due to the method of production and the quality of preservation. However, evaluating the acid-soluble collagen fraction, when available, provides the most accurate 14C dates for leather samples. In instances where gelatinization does not yield sufficient material, the resulting acid-insoluble fraction may be dated. Here we examine the effectiveness of the combined organic solvent and ABA pretreatment with gelatinization for leather samples, as well as the suitability of the acid-insoluble fraction for 14C dating.

Li Youpei, Jiang Wei, Liu Yintao et al.

The domestic research and design of open-hole packers for deep and ultra-deep sulfur-containing wells cannot fully meet the needs of the operation in deep wells. To address the problem, a high-performance compression open-hole packer adapted to the well diameter of ø165.1 mm is developed. The influence of mechanism for maintaining the setting force, the contact angle between the packer rubbers, and the number of splits of the shoulder protect mechanism pair on the packer rubber sealing performance is tested indoor. The shoulder protector and ratchet parameters are optimized, and field tests are carried out. The test results show that the developed compression open-hole packer with bowl-shaped shoulder protector and a unique mechanism to maintain the setting force could allow sealing pressure of 65 MPa in the 180 mm I.D. casing at 150 ℃. The packer has good passability and adaptability in high-temperature and high-pressure gas wells, and meets the requirements of complex well conditions. It addresses the problem of poor tool stability under complex well conditions such as high temperature, high pressure, sulfur-containing and mud environment. The study can provide technical support for the development of complex completion tools.

Emmanuel U. Akpan, Godpower C. Enyi, Ghasem G. Nasr

Abstract Xanthan gum is commonly used in drilling fluids to provide viscosity, solid suspension, and fluid-loss control. However, it is sensitive to high temperatures and not tolerant of field contaminants. This paper presents an experimental study on the effects of an eco-friendly biopolymer (diutan gum) on xanthan gum (XC) in a water-based bentonite mud. Laboratory experiments were carried out for different compositions of the biopolymers in water-based bentonite muds formulated without salt and in water-based bentonite muds containing sodium chloride (NaCl). The rheological properties of the water-based bentonite muds formulated with XC (2 Ibm) and those of the water-based bentonite muds prepared using XC (1Ibm) and diutan gum (1Ibm) were measured using Model 1100 viscometer after aging at 25 °C, 100 °C, and 120 °C for 16 h. The API fluid loss and filter cake of the mud formulations were measured using HTHP filter press. The properties of the water-based bentonite muds containing only XC were compared with those of the water-based bentonite muds containing XC and diutan gum. Presented results show that combining diutan gum and xanthan gum in a ratio of 1:1 in a water-based bentonite mud enhances its performance with respect to fluid properties—apparent viscosity, gel strength, yield points, YP/PV ratio, LSRV, n, and K. The fluid formulations also showed favorable mud cake building characteristics. Experimental data also indicate a 16%, 19%, and 34% reduction in API fluid loss values for the water-based benitoite muds containing XC in the presence of diutan gum after aging at 25 °C, 100 °C, and 120 °C for 16 h, respectively. Experimental results also show that the water-based benitoite mud containing XC and diutan gum would cause less formation damage and was tolerant of contamination with a monovalent cation (Na+). The synergy of xanthan gum and diutan gum can, therefore, improve the performance of water-based drilling fluids.

Pan Qilong, Yin Jieru, Xiao Xinping

The reserve of crude oil in the Arctic area is abundant. Ice melting is making it possible to have intermediate access to the Arctic crude oil and its transportation. A novel compositional data's grey model is proposed in this paper to structurally forecast Arctic crude oil import. Firstly, the general accumulative operation sequence of multivariate compositional data is defined according to Aitchison geometry, then obtaining the novel model with the form of the compositional data vectors. Secondly, this paper studies the least square parameter estimation of the model. The novel model is deduced and selected as the time-response expression of the solution. Thirdly, this paper infuses the novel model with traditional grey model to improve its robustness. Differential Evolution algorithm is introduced to determine the optimal value of the general matrix. Lastly, two validation examples are provided for confirming the effectiveness of the novel model by comparing it with other existing models, before being employed to forecast the crude oil import structure in China. The results show that the novel model provides better performance in all crude oil cases in short-term forecasting. Therefore, by using the new model, China's development parameter is 0.5214 and Determination Factor of the novel model is 0.5999, which means that the crude oil import structure of China is being changed. Specifically, the amount of crude oil imported from the Arctic area is obviously increasing in the next 6 years, showing sufficient proof of the edge owned by the Arctic area: abundant crude oil reserves and shortening transportation distance.