查看更多>>摘要：The hydrate inhibitors played a significant role in preventing hydrate formation in the drilling fluid systems.However,the disposal of these inhibitors was the primary concern for the drilling industries,as Thermodynamic Hydrate Inhibitors(THIs)are not eco-friendly,and Kinetic Hydrate Inhibitors(KHIs)are troublesome to dispose of due to their long polymeric structures.Hence,an attempt had been made to evaluate the Sarcosine,an amino acid,as a biodegradable,green hydrate inhibitor for water-based drilling fluid systems.Initial screening of Sarcosine in the THF-water hydrate(structure-II)system showed that it behaved as a zwitterionic,dual-function inhibitor.It had better inhibition characteristics in delaying induction time and improving rheological and filtration properties than PVCap and PVP while used in formulated mud compositions.The water-based mud used in this work was prepared by mixing carboxymethyl cellulose(CMC),polyanionic cellulose(PAC),xanthan gum(XG),and potassium chloride(KC1)with distilled water.For Sarcosine content water-based mud systems,coefficients of determination(R2)values were dependable,while low-temperature(2 C)rheological values were fitted in Herschel-Bulkley model.These experimental investigations showed that the Sarcosine might be used for the drilling of gas hydrate-bearing formations.
查看更多>>摘要：Life-cycle production optimization aims to obtain the optimal well control scheme at each time control step to maximize financial profit and hydrocarbon production.However,searching for the optimal policy under the limited number of simulation evaluations is a challenging task.In this paper,a novel production optimization method is presented,which maximizes the net present value(NPV)over the entire life-cycle and achieves realtime well control scheme adjustment.The proposed method models the life-cycle production optimization problem as a finite-horizon Markov decision process(MDP),where the well control scheme can be viewed as sequence decisions.Soft actor-critic,known as the state-of-the-art model-free deep reinforcement learning(DRL)algorithm,is subsequently utilized to train DRL agents that can solve the above MDP.The DRL agent strives to maximize long-term NPV rewards as well as the control scheme randomness by training a stochastic policy that maps reservoir states to well control variables and an action-value function that estimates the objective value of the current policy.Since the trained policy is an explicit function structure,the DRL agent can adjust the well control scheme in real-time under different reservoir states.Different from most existing methods that introduce task-specific sensitive parameters or construct complex supplementary structures,the DRL agent learns adap-tively by executing goal-directed interactions with an uncertain reservoir environment and making use of accumulated well control experience,which is similar to the actual field well control mode.The key insight here is that the DRL method's ability to utilize gradients information(well-control experience)for higher sample efficiency.The simulation results based on two reservoir models indicate that compared to other optimization methods,the proposed method can attain higher NPV and access excellent performance in terms of oil displacement.
查看更多>>摘要：The impedance-graded material(IGM)systems can be used as a protective structure to attenuate the stress.Due to the fluidic oscillator of the down-the-hole(DTH)hammer made by cemented carbide was broken during the test,it is urgent to design a protective structure to decay the stress transferred to the fluidic oscillator.This paper studied the stress attenuation effect of Steel-Poly-ether-ether-ketone(PEEK)-layered-protective-structure(SPLPS)subjected to low-velocity impact loadings.The contact state of samples is measured by pressure-sensitive test paper.The experiments were carried out by the split Hopkinson pressure bar(SHPB)method.The stress attenuation effect of 5-layer SPLPS was tested at the different impact velocities.A three-dimensional numerical simulation model is established to simulate the SHPB experiments with the same boundary conditions.The stress attenuation effect of different layers of SPLPS is compared by numerical simulation.Besides,the influence of the thickness of steel-sheet and PEEK-sheet is investigated.And the SPLPS made for the DTH hammer has been tested in the hot dry rock drilling field.The results show that the data of numerical simulation are consistent with the SHPB experimental results.It is found that the different impact velocities do not change the contact state of the sample's end face.The stress attenuation ratio of 5-layer SPLPS in numerical simulation and experiment is 77%.The attenuation ratio increases rapidly when the number of SPLPS layers changes from 1 to 4.When the number of SPLPS layers exceed 4,the attenuation ratio does not increase significantly.Additionally,the thickness of 6 mm and 8 mm are suitable parameters for the SPLPS.The field test has proved that the SPLPS could protect the fluidic oscillator effectively.
Flavio de Andrade SilvaHans Joakim SkadsemVictor Nogueira Lima
11页
查看更多>>摘要：Oil well cement paste is a key structural component in wells that should provide mechanical support to the casing and prevent uncontrolled flow of formation fluids along the wellbore and to the environment.Since the annular cement paste is subjected to both hydrostatic pressure and to loads from formation or through the casing,it is important to understand the mechanical behavior and strength of oil well cement pastes under confining conditions.We study cement specimens cored from test sections that were cemented using a full-scale batch mixer.The specimens were tested mechanically without confinement and under 10,20 and 40 MPa confining pressures using a state of the art triaxial test system.Unconfined samples are found to exhibit linear elastic behavior up to axial strains of approximately 0.2% with an average Young's modulus of 14.9 GPa and a Poisson ratio of 0.21.At larger strains,the stress-strain response deviates from the initial slope,terminating with a brittle shear failure at axial strains of approximately 0.5%.The corresponding average uniaxial compressive strength is 58 MPa,in good agreement with previously published results.When subjected to confining pressures of 10 MPa or higher,the cement paste accommodated larger strains at a given level of deviatoric stress,and maintained its load-carrying capacity through the entire test cycle.The Young's modulus for the initial loading phase was found to decrease with increasing confining pressures,and the ultimate deviatoric stress approached approximately 80 MPa,independent of the magnitude of the confining pressures used in this study.The results suggest that the main effect of increasing confining pressure is to increase the sample ductility and the axial strain corresponding to the ultimate deviatoric stress.It is further found that the confined stress-strain behavior of the oil well cement paste can be described by a simple nonlinear constitutive equation.The more ductile and flexible response of well cement under relevant confining pressures is considered to be a positive characteristic of cement as a barrier material for zonal isolation.This study is based on a commercial well cement slurry that is mixed and placed using field equipment.The results are therefore considered novel and unique,and can contribute toward improved knowledge and evaluation of mechanical well cement behavior under realistic,confined conditions.
Dmitriy A.MartyushevSuresh Kumar GovindarajanYingwen Li
11页
查看更多>>摘要：Injection of acidic formulations into a carbonate reservoir is commonly used in the oil industry to enhance or restore well productivity.The purpose of this method is to create empty channels,the so-called wormholes,which pass deeper into the formation further than the perforated area in the near-wellbore zone of the formation.During the oil production,wormholes become pathways for crude oil to flow into wells.Most of the experimental and numerical studies carried out on this issue are limited in their observations,because they think the issue of wormhole formation only depending on the technological parameters of acidizing(speed and volume of injection).Our study aimed at investigating the effect of the material composition(content of calcite and dolomite)of carbonate rocks on the efficiency of acid treatments.We focus on investigating the effect of the percentage of calcite and dolomite fractions in a carbonate rock on acidizing efficiency,and try to elaborate the influence caused by the percentage of calcite and dolomite associated with the carbonate samples.Note that not all carbonate rocks need to use the same technological parameters for acidizing.However,it is necessary to individually select a few critical technological parameters based on the holding time of the composition in the reservoir as well as on the volume of the composition.In conclusion,the authors have developed recommendations for the application of acid treatment of oil fields in the Perm Krai(Russia),which differ in the material composition of the rock.At one of the oil fields,the authors have conducted pilot tests considering the developed recommendations and received a significant increase in oil recovery(on average,an increase of 1.5-2.0 times)compared to the previous acidizing measures.The results obtained have scientific and practical significance and prospects for further improvement of acid action in carbonate reservoirs.
Gabriel M.P.AndradeDiego Q.F.de MenezesRafael M.Soares
20页
查看更多>>摘要：In the present work,virtual flow metering(VFM)tools are developed to provide estimates for the individual flow rate measurements of the wells operated simultaneously in typical oil and gas platforms.Data reconciliation(DR)procedures are used to calibrate phenomenological models using available measured profiles of well pressure and temperature,and overall flow rates of gas,oil and water.In order to evaluate the relative importance of key hypotheses,three different phenomenological models were used to describe the platform operation:(i)a simple single phase fluid flow model,to evaluate whether the DR task can be successfully accomplished with the available data;(ii)a simple multiphase fluid flow model,in order to evaluate whether the explicit consideration of the multiphase nature of the problem can affect the obtained DR results;and(iii)a detailed phenomenological multiphase flow model,to represent accurately the behavior of an oil and gas production platform.Obtained results show that the proposed DR scheme can be indeed implemented successfully in the form of a VFM sensor to assign online and in real time the individual production of wells operated simultaneously in typical oil and gas platforms.The DR-based VFM was able to reconcile total oil and total water flow rates with average relative deviations of 0.87% and 17% respectively and maximum deviation of 2.3% for oil flow rates.Besides,the DR-based VFM tool provided insights about the system behavior and sensoring management,being able to indicate the oil lines and sensors that were subject to i the highest variability.
查看更多>>摘要：Under the high-temperature and high-pressure(HTHP)conditions in the ground,the environmental features of drilling fluid additives may change to some extent.But the relevant information of the influence of HTHP environment on drilling fluid additives is very limited.Four typical additives,namely,sulfonate asphalt(SEB),potassium polyacrylamide(KPAM),potassium humate(KHm)and xanthan gum(XG),were treated for 40 min under two typical bottom hole conditions of 7 MPa,90 ℃ and 11 MPa,120 ℃.The biodegradability and biotoxicity of these additives before and after treatments were determined.The structures of the four additives were also analyzed by Fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),nuclear magnetic resonance spectroscopy(NMR),thermogravimetric analysis(TGA)and gas chromatography-mass spectrometry(GC-MS).The results revealed no remarkable difference in biotoxicity and biodegradability of each sample between the two conditions.SEB became nontoxic from microtoxic after being treated with HTHP,with the value of EC_(50)notably increased from 2463 to 33,398 mg L~(-1),which might be due to the relative increase of light components observed by GC-MS.Original XG was nontoxic(EC_(50)= 21,000 mg L~(-1))and easily biodegraded(BC ratio = 0.469),but HTHP treatments increased the toxicity(EC_(50)= 5701 mg L~(-1))and decreased the biodegradability(BC ratio = 0.02),which could be attributed to the reduce of the C-OH/C-O-C bonds observed by FT-IR and XPS spectra.Both KPAM and KHm were midtoxic and had low degradability,and only KPAM became highly toxic(EC_(50)<100 mg IT1)after HTHP treatments,which might result from the slight increase in the relative peak area of the amide group.The results could provide preliminary insights into the mechanism of how the HTHP conditions impacted the pollution properties of the additives and pave a new and facile route for the screening of environmentally friendly additives,and consequently mitigate the pollution from the source in the oil and gas exploitation industry.
查看更多>>摘要：Solid scales can cause significant problems in oil production and transmission systems such as oil flow rate reduction.Wax is one of the most critical substances that are highly prone to precipitate and deposit in oil pipelines.This occurrence typically happens in low temperatures,and can extremely affect the flow rate.In the wax deposition process,wax disappearance temperature(WDT)is a crucial factor since it denotes the lowest temperature,at which wax deposits melt and the consequences of wax deposition vanish.In this research,smart models were utilized to predict WDT as a function of molar mass and pressure according to a comprehensive database.The proposed intelligent models are radial basis function(RBF)and multilayer perception(MLP)neural networks,adaptive neuro-fuzzy inference system(ANFIS),random forest(RF),extra tree(ET),and decision tree(DT).The MLP networks were trained with Bayesian Regularization(BR)and Levenberg-Marquardt(LM)algorithms,and the ANFIS models were coupled with three optimization algorithms,namely Cultural Algorithm(CA),Biogeography-based Optimization(BBO),and Teaching-Learning-Based Optimization(TLBO).Results demonstrate that the developed RF model could present an outstanding performance and provide predictions for WDT with the lowest average absolute percent relative error(AAPRE = 0.246%),the maximum coefficient of determination(for predicting = 0.993),and minimum root mean squared error(RMSE = 1.01).Trend analysis showed that increasing pressure and molar mass leads to wax disappearance temperature increase.Lastly,outlier discovery was performed using the Leverage approach to recognize the suspected data points.The outlier detection found that only 6 points(out of 346)are located in the upper and lower suspected data zones.
查看更多>>摘要：Oil and gas metering is primarily used as the basis for evaluating the economic viability of oil wells.Owing to the economic implications of oil and gas metering,the subject of oil and gas flow rate measurement has witnessed a sustained interest by the oil and gas community and the academia.To the best of the audiors'knowledge,despite the growing number of published articles on this subject,there is yet no comprehensive critical review on it.The objective of this paper is to provide a broad overview of models and modelling techniques applied to the estimation of oil and gas flow rate through chokes while also critically evaluating them.For the sake of simplicity and ease of reference,the outcomes of the review are presented in tables in an integrated and concise manner.The articles for this review were extracted from many subject areas.For the theoretical pieces related to oil and gas flow rate in general,the authors relied heavily upon several key drilling fluid texts.For operational and field studies,the audiors relied on conference proceedings from the society of petroleum engineers.These sources were supplemented with articles in peer reviewed journals in order to contextualize the subject in terms of current practices.This review is interspersed with critiques of the models while the areas requiring improvement were also outlined.Findings from the bibliometric analysis indicate that there is no universal model for all flow situations despite the huge efforts in this direction.Furthermore,a broad survey of literature on recent flow models reveals that researchers are gravitating towards the field of artificial intelligence due to the tremendous promises it offers.This review constitutes the first critical compilation on a broad range of models applied to predicting oil and gas flow rates through chokes.
查看更多>>摘要：In this paper,a damped iterative ensemble Kalman filter(IEnKF)technique has been developed and integrated with a recently modified pressure-gradient-based(PGB)sand failure criterion to implicitly and inversely characterize the dynamic wormhole network during cold heavy oil production with sand(CHOPS)processes.With an improved upscaling process,not only has a microscopic PGB sand failure criterion been properly upscaled to the grid-scale simulation,but also it can be dynamically,implicitly,and inversely determined.Then,such a sand failure model togetber with three-phase relative permeability is validated and applied to reproduce wormhole network in a laboratory experiment conditioned to its sand production profile.Good agreements between the observed and simulated cumulative production profiles including oil,gas,and sand have been achieved with satisfactory convergence by integrating the ensemble-based history matching method.The simulated wormhole network has shown its great similarity to the experimental observations,while the convergence of the ensemble-based history matching algorithm is greatly improved with a widespread of initial ensembles in each grid.Furthermore,deviations between the observed and updated production profiles can be significantly minimized by dividing the entire production period into three sequential stages,each of which has its distinct relative permeability curves due to the major effect(i.e.,foamy oil flow,sand failure,and slurry flow)on its multiphase flow behaviours,respectively.By integrating the ensemble-based sand failure model with the damped-IEnKF method,the dynamic wormhole network during a CHOPS process can be accurately characterized with satisfactory convergence,demonstrating its robustness and practicality of dynamically and inversely simulating the preferential wormhole network.Such an ensemble-based sand failure model can be seamlessly incorporated with any commercial reservoir simulators under various conditions.
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