This paper presents a pore-scale model proposed for numerical simulation of fines migration in porous media. The model simulates the behavior of spherical particles with different radii in flow by coupling lattice Boltzmann method (LBM) as a computational fluid dynamics (CFD) solver for the simulation of the fluid flow with a rigid body physics engine responsible for the simulation of the particulate transports. To achieve this, the basic LBM algorithm was extended to treat the curved particle boundaries, and a fluid-particle force interaction was implemented in order to account for the exerted force acting on the particles by the fluid and subsequent particulate movements. The accuracy and reliability of the proposed numerical model were successfully validated by simulating Poiseuille flow and Stokes flow and comparing the simulation results with those of the analytical solution. Thereafter, it was employed to simulate the migration of fine particles through synthetic 2D porous media. The simulation results were also presented to investigate the influence of fines migration on the porosity and permeability of the medium, and more interestingly on the hydraulic tortuosity as a criterion for changes in preferential flow path. As will be shown, the developed numerical method is able to successfully capture major retention mechanisms responsible for fines migration associated formation damage including external cake formation by the large particles, internal cake formation by the small particles, pore plugging, and surface deposition. This work provides a framework for further investigations regarding pore-scale phenomena associated with fines migration in the porous media.

There are new challenges for plant operators due to the increase share of renewable energy. Plant Operators must maintain high reliability and high profits while plants are being required to be more flexible to compensate for the variable generation addition of these renewables into the grid. Plant operators must deal with the thermal strain and the wear-and-tear of such operations. The aim of this study was to determine which machine learning algorithm gives the best estimation of boiler component remaining useful life using plant operations. The flexible operation for all units was estimated using the Intertek hourly MW analysis and damage modeling software Loads Model ™ . We used several plant features as predictors (such as equipment manufacturer, operating regime, ramp rates, etc. We tested five different Machine Learning techniques and found that Gradient Boost is the best approach to predict the reduction in Life Span of the plant with over 90% precision.

Mud pollution seriously restricts the development of tight gas reservoirs. For the Dabei tight gas field in Tarim Basin, lots of wells show a higher skin factor on the pressure buildup test curves after drilling. Little researches on mud damage have been conducted for the fracture gas reservoir. Based on the previous researches, a dynamic filtration experimental method utilizing full diameter cores is established for fracture-porous cores under reservoir temperature. Twelve sets of dynamic filtration tests with full diameter cores (D = 10 cm) on the established device and some cuttings microscopic analysis on environmental-scanning-electron microscope/energy dispersive X-ray detector (ESEM/EDX) have been conducted. The effects of core type, fracture width, pressure difference, and mud type on mud damage are all investigated. The results show that the fractured cores suffer a more serious damage degree and exhibit lower return permeability ratio, compared with the porous cores. And the damage degree of fractured cores is proportional to the fracture width and pressure difference. The solids invasion is the key factor damaging the fractured cores, while the porous is mainly impaired by the filtrate invasion. This paper provides a scientific, in-depth understanding of the behaviors, laws, and characteristics of mud damage in fractured and porous cores.

In order to obtain an optimal design of composite offshore wind turbine blade, take into account all the structural properties and the limiting conditions applied as close as possible to real cases. This work is divided into two stages: the aerodynamic design and the structural design. The optimal blade structural configuration was determined through a parametric study by using a finite element method. The skin thickness, thickness and width of the spar flange, and thickness, location, and length of the front and rear spar web were varied until design criteria were satisfied. The purpose of this article is to provide the designer with all the tools required to model and optimize the blades. The aerodynamic performance has been covered in this study using blade element momentum (BEM) method to calculate the loads applied to the turbine blade during service and extreme stormy conditions, and the finite element analysis was performed by using abaqus code to predict the most critical damage behavior and to apprehend and obtain knowledge of the complex structural behavior of wind turbine blades. The approach developed based on the nonlinear finite element analysis using mean values for the material properties and the failure criteria of Hashin to predict failure modes in large structures and to identify the sensitive zones.

Produced water re-injection (PWRI) is an important economic and environmental-friendly option to convert waste to value with waterflooding operations. However, it often causes rapid injectivity decline. In the present study, a coreflood test on a low permeable core sample is carried out to investigate the injectivity decline behavior. An analytical model for well impedance (normalized reciprocal of injectivity) growth, along with probabilistic histograms of injectivity damage parameters, is applied to well injectivity decline prediction during produced water disposal in a thick low permeable formation (Völkersen field). An impedance curve with an unusual convex form is observed in both coreflood test and well behavior modeling; the impedance growth rate is lower during external filter cake build-up if compared with the deep bed filtration stage. Low reservoir rock permeability and, consequently, high values of filtration and formation damage coefficients lead to fast impedance growth during deep bed filtration; while external filter cake formation results in relatively slow impedance growth. A risk analysis employing probabilistic histograms of injectivity damage parameters is used to well behavior prediction under high uncertainty conditions.

Ultradeep fractured tight sandstone gas reservoir is easy to suffer from severe formation damage during the drill-in process, yet few papers have been published on the corresponding formation damage mechanisms. This paper focuses on a typical ultradeep fractured tight sandstone reservoir in the Tarim Basin, China. Fluid sensitivity damage, phase trapping damage, and the formation damage induced by oil-based drill-in fluids were evaluated by a serious of modified experimental methods. As a supplement, the rock physics and surface property were analyzed deeply. Results showed that severe fluid sensitivity damage occurred with a decrease in fluid salinity (critical value: 3/4 formation water salinity (FWS)) and an increase in fluid p H value (critical value: pH = 7.5). The change in water film thickness, the enhancement of hydrophilia, particle detachment, and dissolution of quartz/albite under high formation temperature are the main damage mechanisms. Abnormal low water saturation, mixed wettability, abundant clay minerals, and complex pore structures are contributing to the severe phase trapping damage. The dynamic damage rate of oil-based drill-in fluids is 60.01%, and inadequate loading capacity is the main trigger of lost circulation. Finally, a formation damage control strategy was proposed, and a field test proved its feasibility.

The damage mechanism of fracturing fluids has always been the hot research topic in the development of low-permeability reservoir with hydraulic fracturing. At present, the research in this area is conducted mostly by the conventional core fluid flow test designed with industrial standards, less in the experiment operated from a microperspective. Against the reservoir cores with different permeability, and based on the results of SEM, mercury injection experiment, and core fluid flow test, this paper uses the technology of nuclear magnetic resonance (NMR) to systematically analyze the degree and rule of water-sensitivity, water-block, and solid-phase adsorption damage resulted from hydroxypropyl guar gum (HPG) and carboxymethyl guar gum (CMG) fracturing fluids, and proposes a comprehensive test method for evaluating the fracturing fluids damage to the reservoir. The test results show that fracturing fluid infiltrating into the core causes the increase of bound water, mobile water retention, and solid-phase macromolecule substance absorption inside the core in varying degrees, decreasing the reservoir permeability. The extent of reservoir water-sensitivity damage is positively correlated with the increment of bound water, and the extent of water-block damage is positively correlated with mobile water retention volume. The adsorption and retention of solid-phase macromolecule substance causes largest loss of core permeability, averaging about 20%, and it is main damage factor of fracturing fluids, the water-sensitivity damage causes 11% of core permeability loss, and the water-block damage causes 7% of loss. As the reservoir permeability doubles, the comprehensive damage resulted from guar gum fracturing fluid decreases by 14%. The comprehensive damage of CMG fracturing fluid to reservoir is 6.6% lower than that of HPG fracturing fluid, and the lower the reservoir permeability, the larger the gap between damage of CMG and HPG fracturing fluids. With the technology of NMR, the objective and accurate evaluation of various damages to reservoir resulted from fracturing fluids is realized, and the corresponding relation between damage mechanism and damage extent is established, which provides reference for research on improvement of fracturing fluid properties and reservoir protection measures.

Formation damage from aqueous phase trapping in low-permeability sandstones can be removed using mutual solvents, blends of alcohols and mutual solvents, and surfactants. These treatments modify the interfacial tension of the trapped fluids or the wettability of the formation. However, treatments intended to remove a certain type of damage may cause other types of formation damage due to incompatibility with the rock and formation fluids. High-frequency acoustic waves have been used in industrial applications to clean up and remove contaminants. Important studies have been conducted to extend the use of acoustic waves for wellbore stimulation. This technical paper presents a laboratory investigation to determine the effects of ultrasonic (UT) treatment on interfacial tension and wettability alteration during invasion of fracturing fluids treated with surfactants in low-permeability sandstones. An experimental program consisting of a series of spontaneous imbibition experiments was conducted to measure the spontaneous imbibition potential of sandstone rock cores treated with surfactants in the presence of UT energy. Spontaneous imbibition tests were conducted in two steps. In the first, spontaneous imbibition tests were conducted on untreated low-permeability sandstone core samples in the presence of UT radiation. In the second step, spontaneous imbibition tests were conducted on cores flooded with surfactant while exposing the core to UT radiation from an acoustic horn. In each series experiments, the power output was changed to monitor the effect of acoustic power on wettability alteration. Results obtained from the experiments showed that acoustic stimulation improves imbibition of water in both water wet and intermediate wet cores. Wettability alteration is attributed to enhancement of capillary forces in water wet cores. For cores treated with water repelling surfactants, improvement in imbibition is attributed to detachment of surfactant molecules from the pore walls due to acoustic streaming of sonic waves. This research was originally intended to investigate removal of trapped water from fluid injection of low-permeability sandstones by acoustic stimulation. However, the obtained results show that it is possible to improve the recovery of trapped hydrocarbon in low-permeability sandstones under the influence of acoustic stimulation.

The sandstone rocks' integrity and consolidation may be highly affected by the type and the strength of the stimulation fluids. Strong acids such as HF/HCl impair the rock consolidation. The reduction in the sandstone rock consolidation will trigger the sand production. Sand causes erosion of downhole and surface equipment especially when it is produced with high gas flow rates. In this study, gentle stimulation fluids for sandstone that consists of chelating agents and catalyst were proposed. The chelating agents are diethylene triamine penta acetic acid (DTPA) and ethylene diamine tetra acetic acid (EDTA). This is the first time to introduce a catalyst (potassium carbonate) in sandstone acidizing. Potassium carbonate was found to work as a clay stabilizer and catalyst that enhances the dissolution of chlorite clay mineral in the sandstone rock. The objective of introducing the catalyst is to enhance the solubility of the insoluble minerals such as chlorite clay minerals. The change in the mechanical properties of sandstone rocks (Bandera and Berea) was evaluated. The possibility of the formation damage after using seawater-based chelating agents was investigated and compared to HF/HCl mud acid. Coreflooding experiments were conducted to evaluate the effect of these fluids on the rock integrity. Computed tomography (CT) scanner was used to assess the formation damage. Different models were used to predict the sand production possibility after the stimulation with chelating agent/catalyst, and this was compared to the HF/HCl mud acid. The results showed that the permeability of sandstone core increased after acidizing. The reduction in CT-number after acidizing confirmed that no formation damage occurred. Rock mechanics evaluation showed no major changes occurred in the rock moduli and no sand production was observed. The model results showed that using chelating gents to stimulate Berea (BR) and Bandera (BN) sandstone cores did not cause sand production. Applying the same models for cores stimulated by HF/HCl acids indicated high possibility of sand production. The addition of potassium carbonate to DTPA chelating agents enhanced the chlorite clay mineral dissolution based on the inductively coupled plasma (ICP) analysis. Potassium carbonate as a catalyst did not affect the sandstone integrity because it only enhanced the dissolution of chlorite clay minerals (selective dissolution) and did not affect the solubility of carbonate minerals which are the primary cementing materials in the sandstone cores. A new dimensionless number was developed that describes the relation between the number of pore volumes (PVs) contacted the rock and the radial distance from the wellbore.

This work evaluated the genotoxic potential of the soluble organic material (SOM) extracted from the particulate matter (PM) emitted by an automotive diesel engine. The engine was modified to operate with a home-made multipoint-port injection system to substitute 10% of ultralow-sulfur diesel (ULSD) fuel in energy basis by hydrous ethanol (h-Et) or n-butanol (n-Bu) injected into the manifold during the intake stroke. A low engine load mode named M4 (43 N·m at 2410 min −1 ) and a medium-load mode M2 (95 N·m at 2410 min −1 ) were selected from the vehicle homologation cycle. PM was collected with a stainless steel filter located 1.5 m downstream the exhaust manifold. The SOM of the PM was extracted to evaluate the genotoxic activity on human lymphocytes using the comet assay. Results indicated that independently of the mode, the SOM coming from alcohols led more genotoxicity than ULSD, following the order h-Et > n-Bu > ULSD. The low engine load operation exhibited much more deoxyribonucleic acid (DNA) damage than mode M2, especially the PM produced by hydrous ethanol port-injection. Although further research is still necessary, these findings suggest that the biology activity of the SOM coming from alcohols PM could be a barrier for the implementation of alcohol port-injection technology.

Disasters such as offshore oil spills will have a significant negative impact on occupations, incomes, tariffs, and further profits, adding to the struggles of regional area held up in difficulty. Such a broad size of impact can more impair the functioning of the economy of the district. In addition to costs encountered by cleanup activities, industries and individuals dependent on coastal resources can experience huge economic losses. Many other related businesses and sectors can possibly hurt by disruptions and loss of earnings. To better understand different aspects of the problem, we explain the problem through a case study for recent incident in the Gulf of Mexico (GoM), the Deepwater Horizon oil spill (DWH) on April 20, 2010, the worst oil spill disaster in the history of the U.S. start off the coastline of Louisiana in the Gulf of Mexico. We have conducted study to focus on the positive impact of economic compensation on Gulf coast employment and wages. Regardless of estimates of main job losses resulting from the oil spill, we estimated that Louisiana experienced a net rise in employment and wages. Input–output (I-O) model will be applied in this study to approximate the economic compensation created by economic injection due to the Deepwater Horizon accident. Then, we can estimate the gross damages to the Louisiana economy. More importantly, the final results should provide useful information on measuring the economic impact of any future large-scale disasters and for how companies must react to minimize the economic impact of events. One positive side that will come out of the oil spill is the spotlight on the need for new and developed prevention and response strategies to this kind of major disasters. The analysis of losses in the employment and earnings in Louisiana in the aftermath of accidents in petroleum industry makes to know the importance and significance of the oil and gas sector as a powerful economic machine that provides a wide range of opportunity for the state. It is no surprise how remarkable is the influence of oil and gas industry on the income of the state workers and the output of the state. Therefore, having approximation of the impact helps to facilitate strong recovery and to prevent potential harm to the related industry.

Reinjection is one of the most important methods to dispose fluid associated with oil and natural gas production. Disposed fluids include produced water, hydraulic fracture flow back fluids, and drilling mud fluids. Several formation damage mechanisms are associated with the injection including damage due to filter cake formed at the formation face, bacteria activity, fluid incompatibility, free gas content, and clay activation. Fractured injection is typically preferred over matrix injection because a hydraulic fracture will enhance the well injectivity and extend the well life. In a given formation, the fracture dimensions change with different injection flow rates due to the change in injection pressures. Also, for a given flow rate, the skin factor varies with time due to the fracture propagation. In this study, well test and injection history data of a class II disposal well in south Texas were used to develop an equation that correlates the skin factor to the injection flow rate and injection time. The results show that the skin factor decreases with time logarithmically as the fracture propagates. At higher injection flow rates, the skin factor achieved is lower due to the larger fracture dimensions that are developed at higher injection flow rates. The equations developed in this study can be applied for any water injector after calibrating the required coefficients using injection step rate test (SRT) data.

Well stimulation using acidic solutions is widely used to treat carbonate formations. The acidic fluids remove the near-wellbore damage and create channels around the wellbore by dissolving fraction of the carbonate rocks. Many stimulation fluids have been used such as hydrochloric acid (HCl) acid, organic acids, and chelating agents to stimulate carbonate reservoirs. Wormholes that are created by these fluids are very effective and will yield negative skin values and this will enhance the well productivity. In addition to the wormhole creation, the diffusion of these fluids inside the pores of the rock may create significant and permanent changes in the rock mechanical properties. These changes can eventually lead to weakening the rock strength, which may lead to future formation damage due to the wellbore instability. In this paper, the effect of ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) chelating agents on the carbonate rocks elastic properties was investigated. The effect of wormholes created by chelating agent on the rock mechanical properties was investigated. Computed tomography (CT) scan and acoustic measurements were conducted on the core samples before and after matrix stimulation treatments. Experimental results showed that the mechanical properties of strong rocks such as Indiana limestone (IL) cores were not affected when chelating agents were used to stimulate those cores. On the other hand, less strong rocks such as Austin chalk (AC) show significant alteration on the rock elastic properties when chelating agents were used as stimulation fluids.

Extreme weather events seem to have become more frequent with climate change. These anomalies throughout the world may generally be categorized as drought, heavy rain storms, landslides, heavy snow storms, sea level rise, ice melts from the polar regions, tornadoes and hurricanes. The environmental and real property damage caused may be minimized if proper planning and best practices are engineered into place before the catastrophic events occur. The management of vulnerable areas should definitely include such plans and strategies. The purpose of the current work is to point to the best practices already being carried out in some areas, and to draw attention to some of the knowledge embodied in the indigenous populations in particular regions, which have come by this knowledge via generations of survival through adverse climate/environmental changes. The integration of this indigenous knowledge where applicable, with modern engineering tools and techniques will help the world better to face the climatic challenges ahead.

Carbonate reservoir stimulation has been carried out for years using HCl or HCl-based fluids. High HCl concentration should not be used when the well completion has Cr-based alloy in which the protective layer is chrome oxide which is very soluble in HCl. HCl or its based fluids are not recommended either in shallow reservoirs where the fracture pressure is low (face dissolution) or in deep reservoirs where it will cause severe corrosion problems to the well tubular. Different chelating agents have been proposed to be used as alternatives to HCl in the cases that HCl cannot be used. Chelating agents, such as HEDTA (hydroxyl ethylene diamine triacetic acid) and GLDA (glutamic –N, N-diacetic acid), have been used to stimulate carbonate cores. The benefits of chelating agents over HCl are the low reaction, low leak-off rate, and low corrosion rates. In this study, the different equations and parameters that can be used in matrix acid treatment were summarized to scale up the laboratory conditions to the field conditions. The conditions where HCl or chelating agents can be used were optimized and in this paper. The leak-off rate was determined using the data from coreflood experiments and computed tomography (CT) scans. Indiana limestone cores of average permeability of 1 md and core lengths of 6 and 20 in. were used in this study. Chelating agents will be used at pH value of 4 and at concentration of 0.6M, and their performance will be compared with the 15 wt.% HCl. The experimental results showed that HCl has high leak-off rate and caused face dissolution at low injection rate. The model to scale up the linear coreflood results to radial field conditions was developed and can be used to design for the optimum conditions of the matrix acid treatments. Chelating agents can be used to stimulate shallow reservoirs in which HCl may cause face dissolution, because they can penetrate deep with less volume and also they can be used in deep reservoirs where HCl may cause severe corrosion to the well tubular.

Rate decline analysis is a significant method for predicting well performance. Previous studies on rate decline analysis of fractured wells are all based on homogeneous reservoirs rather than homogeneous ones considering fracture face damage. In this article, a well model intercepted by a finite conductivity vertical fracture with fracture face damage is established to investigate how face damage factor affects the productivity of fractured well. Calculative results show that in transient flow, dimensionless rate decreases with the increase of fracture face damage and in pseudo steady-state flow, all curves under different face damage factors coincide with each other. Then, a new pseudo steady-state analytic formula and its validation are presented. Finally, new Blasingame type curves are established. It is shown that the existence of fracture damage would decrease the rate when time is relatively small, so fracture damage is an essential factor that we should consider for type curves analysis. Compared with traditional type curves, new type curves could solve the problem of both variable rate and variable pressure drop for fractured wells with fracture face damage factor. A gas reservoir example is performed to demonstrate the methodology of new type curves analysis and its validation for calculating important formation parameters.

Liquid loading has been a problem in natural gas wells for several decades. With gas fields becoming mature and gas production rates dropping below the critical rate, deliquification becomes more and more critical for continuous productivity and profitability of gas wells. Current methods for solving liquid loading in the wellbore include plunger lift, velocity string, surfactant, foam, well cycling, pumps, compression, swabbing, and gas lift. All these methods are to optimize the lifting of liquid up to surface, which increases the operating cost, onshore, and offshore. However, the near-wellbore liquid loading is critical but not well understood. Through numerical reservoir simulation studies, effect of liquid loading on gas productivity and recovery has been quantified in two aspects: backup pressure and near-wellbore liquid blocking by considering variable reservoir permeability, reservoir pressure, formation thickness, liquid production rate, and geology. Based on the new knowledge, we have developed well completion methods for effective deliquifications. These lead to better field operations and increased ultimate gas recovery.

Injectivity decline due to injection of water with particles is a widespread phenomenon in waterflood projects. It happens due to particle capture by rocks and consequent permeability decline and also due to external cake formation on the sandface. Since offshore production environments become ever more complex, particularly in deep water fields, the risk associated with injectivity impairment due to injection of seawater or re-injection of produced water may increase to the point that production by conventional waterflood may cease to be viable. Therefore, it is becoming increasingly important to predict injectivity evolution under such circumstances. The work develops a semi-analytical model for injectivity impairment during a suspension injection for the case of filtration and formation damage coefficients being linear functions of retained particle concentration. The model exhibits limited retained particle accumulation, while the traditional model with a constant filtration coefficient predicts unlimited growth of retained particle concentration. The developed model also predicts the well index stabilization after the decline period.

Flow of particulate suspension in porous media with particle retention and consequent permeability reduction is discussed. Using analytical model for suspension injection via single well, the permeability damage zone size was defined and expressed by transcendental equation. Analysis of field data shows that usually the size of damaged zone does not extend more than 1 m beyond the injector. The definition of damage zone size is used for design of well stimulation via deposition removal.