查看更多>>摘要：In the actual production process of the oil field, the functionality of the oil well pumps will be negatively affected by many factors such as manufacturing quality, installation quality, sand, wax, water, gas, heavy oil, and corrosion, which will cause great loss to the production. Therefore, it is very important to analyze the working conditions of the rod pumping systems. In actual oilfield production, the working conditions of deep well pumps are analyzed based on the measured surface indicator diagrams. However, traditional computer diagnosis of pumping wells relies on necessary mathematical methods, or deep networks with many parameters. These methods require a lot of data, with complex analysis processes, long testing time and low efficiency. This article studies the application of meta-transfer learning in the diagnosis of rod pump wells in few-shot scenarios. Meta transfer learning combines the advantages of both meta-learning and transfer learning. It can not only provide good initial parameters for learners based on deeper networks through the pre-training stage of transfer learning, but also achieve automatic adjustment of hyperparameters with the help of meta-learning. This enables fast gradient iteration and reduces the probability of overfitting, thereby improving model performance. We also conduct comparative experiments to compare the experimental performance of this method with classical meta learning methods and deep convolutional networks on the classification problem of indicator diagrams. According to the experimental results, the accuracy rate of meta-transfer learning in the diagnosis of few-shot working conditions in practical problems is close to 80%, which is better than the 70% accuracy rate of the comparative experiments. In the actual oil field, there are not many indicator diagrams for pumping unit diagnosis, so this method can well meet the needs of fault detection.
Auad, Isabella TomasellaYamamoto, MarcioCarrion, Ronaldo
6页
查看更多>>摘要：During the subsea well construction and workover, a subsea well is connected to the drillship through the blowout preventer (BOP) and the drilling riser. Environmental loads acting on the drilling riser and the drillship are transferred to the wellhead, conductor, and casings, which can cause fatigue issues at critical points such as at the casing couplings. The main function of a subsea wellhead system is to perform the interface between the BOP and the well, ensuring its integrity throughout its operational life. Factors such as the increase in the weight and height of the BOP on 6th generation platforms contributed to the increased risk of failure due to fatigue. The system in this work is represented by a 3D finite element model including internal cement, conductor, and surface casings. Although simplifications were adopted in the modeling, the essence of the well physical behavior remains. The work addresses the influence of the wellhead stick-up on the maximum stress in the conductor below the seabed, comparing analyses of two wellhead stick-up and including horizontal displacement resulting from the integration of the platform/riser dynamics. These horizontal loads are transferred to the top of the wellhead system as a bending moment and shear force. A time series containing riser horizontal loadings is utilized to obtain the von Mises stress. This information is used to count cycles with the rainflow counting technique. The number of cycles resulting for the two wellhead stick-up is compared and demonstrates how wellhead stick-up can be influenced by an increase in dynamic loads acting on the wellhead top. An influence can be observed on the maximum stress point of the conductor located below the seabed. From these results, it was possible to conclude the wellhead stick-up can influence the depth of a critical point in the conductor below the seabed.
查看更多>>摘要：Traditionally, oil well tests aim to characterize the reservoir permeability field from pressure transient analysis (PTA) of drawdown and build up based on isothermal flow models in porous media. With the advancement of well test instrumentation, more accurate temperature records became available and have encouraged analyses based on non-isothermal models that made possible the temperature transient analysis (TTA). In addition to the characterization of reservoir parameters, such as permeability and porosity by TTA, taking non-isothermal effect into account on PTA represents better physical phenomena, especially in high transmissibility reservoirs and in cases where the pressure sensor is placed away from the sandface. This work consists in the development and numerical implementation of a non-isothermal model of well test considering a unidimensional radial reservoir coupled to a production well and in the use of this simulator, associated with multivariable optimization methods, to solve the inverse problem of reservoir parameters characterization. Nelder-Mead Simplex, NewtonRaphson and BGFS methods were used to evaluate reservoir parameters for one of the reservoir configurations analyzed and the first method presented better computational efficiency. It was then used to solve the inverse problem of radial composite reservoirs.
查看更多>>摘要：Ultrasonic vibration technology as a new type of auxiliary lithotripsy technology, a lot of research on this technology. However, at present, the effect of rock temperature on ultrasonic vibration of rock breaking has not been studied. Therefore, with the help of numerical simulation software, nuclear magnetic resonance detection and penetrant testing methods, it is necessary to complete the numerical simulation and laboratory testing of granite at different temperatures under ultrasonic vibration with granite as the research object. The main results are as follows:1. Under ultrasonic vibration, the number of rock cracks will increase with increasing temperature. And the fracture azimuth intensity in the rock model is 90 degrees concentrated. 2. As the temperature increases, the accumulated thermal damage will promote the large number of expansion and connection of certain internal cracks, resulting in the macroscopic destruction of the rock sample and the increase in crack volume. 3. With the increase of temperature, the increase of porosity of rock samples under ultrasonic vibration has a staged characteristic. And 150 degrees C is the threshold. The significance of this research is to provide theoretical and technical support for the application of ultrasonic vibration technology in the future hard rock geological exploration and deep resource mining.
查看更多>>摘要：In order to solve the problem of conventional preformed particle gel (PPG) with relatively high cost and poor strength and shearing resistance, a preformed sawdust gel particle (S-PPG) with a more superior performance than PPG was presented. A series of S-PPG with different mass ratio of sawdust particles to gelling liquid were prepared with free radical polymerization. It makes acrylic acid and acrylamide as polymerization monomers, N, N '-methylene bisacrylamide as crosslinking agent, ammonium persulfate as initiator and sawdust particles as enhancer. In general, enhancer content was less than 1%, but the content of enhancer in this work was increased by about 20-30%. The microscopic morphology, swelling property, viscoelasticity, yield stress, creep-recovery characteristics and shearing resistance of S-PPG in the formation water had been studied. The plugging behavior of S-PPG was studied using core flooding test. The results indicated that the swelling ratio of S-PPG (1:5) in the formation water was 8. S-PPG showed better viscoelasticity properties, shearing resistance and higher yield stresses than PPG. Moreover, the plugging rate of the plugging system with 3000 mg/L S-PPG (1:5) improved from 85.1% to 90.5% in fracture core compared with PPG. S-PPG (1:3) improved the plugging rate from 85.1% to 91.9%. The research results provide an alternative plugging material in fractured reservoirs.
查看更多>>摘要：Buried channels are considered stratigraphic traps, essential in petroleum exploration and drilling hazard management. A thorough investigation of the buried channels provides helpful information about the sedimentation processes and the marine currents. Hand-operated interpretation of channels is sometimes laborintensive and time-consuming, particularly in areas with complex geological patterns or low signal-to-noise ratios. However, automatic feature extraction is a task-on-demand. Channel boundaries, depicted as curvy and curvilinear events on time slices, are called edges in image processing, where amplitudes intensively vary. This paper provides an improved edge delineation algorithm with a sub-pixel resolution for an enhanced channel boundary depiction. The partial area effect, in combination with a unique edge linking technique, is proposed to strengthen the connectivity of edge segments and the fidelity of edge outlines. First, a gradient-directed partial area effect mask was employed in the edge area of interest to extract the edge position in each pixel with relatively high precision and less affected by environmental noise. Then, an edge linking algorithm based on the edge segments' distance was applied to the partial area effect's results to connect the circular arc edges detected. Field tests were carried out on synthetic and field data sets containing several channelized features with differing widths and tortuosity. The proposed sub-pixel procedure afforded more precise and cost-effective outcomes than approaches with pixel resolutions. The quantitative validation tests using root mean square error, peak signal-tonoise ratio, structural similarity index, and Pearson correlation coefficient revealed that the proposed approach exceeded the traditional edge measures and seismic attributes by detecting more reliable edge points. Finally, we tested the proposed algorithm on synthetic and field seismic data sets containing salt domes and fault events to determine its applicability for localizing other geological features. The detected edges were quantitatively validated based on the manually interpreted events. The salt and fault boundaries detected by the proposed algorithm have relatively high coincidences with their ground truths.
查看更多>>摘要：Quartz cement is a significant authigenic mineral in the tight gas sandstones of the Upper Triassic Xujiahe Formation, fourth member (Xu4 sandstones) in the western Sichuan Basin. Here we report mineralogical, petrological and geochemical data from the Xu4 sandstones to constrain the silica sources of their quartz cements. The quartz cements mainly occur as quartz grain overgrowths and pore-filling quartz cement, with major associated authigenic minerals including calcite, dolomite, illite, kaolinite, and chlorite. The homogenization temperatures of quartz cement fluid inclusions range from 49.2 degrees C to 143.4 degrees C and show a multistage continuous precipitation process. Raman spectrometry results show the presence of methane (CH4) and CO2 in quartz cement fluid inclusions. The dissolution of feldspar, the illitization of kaolinite and smectite, as well as the pressure dissolution of quartz grains provided silica sources for quartz cement. The dissolution of feldspar by organic acid (carboxylic acid) is the main silica source for quartz cement in the 80-120 degrees C interval; the illitization of smectite and kaolinite have different initial temperatures, and both consume potassium. The pressure dissolution of quartz grains results in stylolite formation. The low-temperature quartz cement (<70 degrees C) is mainly derived from the dissolution of feldspar by meteoric water. At the Late Triassic/Jurassic transition, the uplift of the western basin led to leaching by meteoric water in the upper part of the Xu4 sandstone, forming a weakly acidic fluid with a low K+/H+ ratio and giving this type of sandstone low potassium and sodium concentrations.
查看更多>>摘要：This paper investigates the influence of pore space heterogeneity on the adsorption dynamics in a single-phase flow. The sensitivity of adsorption dynamics to changes in heterogeneity, which is numerically described by the disorder parameter, is studied in combination with the Peclet number, porosity, adsorption rate constant, and absolute permeability. The focus is on applied results that are useful, for example, in chemical and petroleum engineering. The main findings of this paper were obtained in mathematical modeling based on lattice Boltzmann equations (LBE) for fluid flow (MRT collision scheme) and mass transfer processes (SRT collision scheme). Mass transfer at the adsorbent/adsorbate interface is described using the kinetics law of Langmuir adsorption. Numerical simulations are performed on digital images of the porous structures generated using Monte-Carlo's movement method, which controls the pore space heterogeneity. In this work, special attention is paid to the choice of the relaxation parameter in LBE for mass transfer, which affects the adsorption dynamics. The results of this paper show that heterogeneity significantly affects the dynamics of the adsorbed amount. An increase in the disorder parameter leads to a decrease in the velocity of the concentration front and a slowdown in the adsorption rate. It was found that the sensitivity of the dynamics of adsorption to a change in heterogeneity is maximum at low Peclet numbers. The impact of the disorder on adsorption significantly decreases with an increase in the Peclet number. With the prevalence of the convection mechanism, the adsorption dynamics is practically unaffected by heterogeneity. The effect of heterogeneity is most pronounced at low porosity and decreases significantly with its growth. At high porosity, the influence of heterogeneity on the adsorption dynamics was not revealed. The Damkohler number affects the sensitivity of the adsorption dynamics to changes in pore space heterogeneity. The effect of heterogeneity increases with the increasing intensity of mass transfer. In addition, it was found that absolute permeability does not affect adsorption.
Alarji, HamadAlazman, AbdulazizRegenauer-Lieb, Klaus
10页
查看更多>>摘要：Acid stimulation is one of the main methodologies to enhance well productivity and increase permeability lost by near-wellbore formation damage through matrix acidizing. The desired outcome of acidizing carbonate rocks is to form deep conductive flow channels called "wormholes". The productivity enhancement depends on how deep these wormholes penetrate into the reservoir. The porous medium is characterized by three fundamental parameters which are anisotropic or isotropic porosity, permeability, and percolation. Here we test the hypothesis that effective tortuosity a key parameter for microstructure characterization in porous media has a significant effect on wormhole formation. Significant progress has been made by empirical work on carbonate acidizing to increase the stimulation efficiency, but further improvements are possible by developing a deeper understanding of the impact of effective tortuosity on wormhole initiation and development. We use Indiana limestone core flooding experiments to inject diluted hydrochloric acid (HCl) at different acid concentrations and injection rates. Effective tortuosity was calculated for the tight Indiana limestone and was compared with an earlier study on the highly porous Mount Gambier limestone to evaluate the effect of tortuosity on wormhole formation. Our results suggest that the inverse Damko center dot hler and Pe ' clet phase space, traditionally used for evaluating criteria for wormhole formation, needs to be extended by tortuosity as a third dimension to capture the effect of microstructure for the initiation of wormhole phenomenon. Incorporating this extension will improve the prediction of wormhole initiation conditions for all carbonate rock types by using a universal dimensionless phase space.
查看更多>>摘要：Surfactant alternating gas/CO2 (SAG) flooding is a promising enhanced oil recovery (EOR) technology, which has the potential to improve oil production beyond primary and secondary water flooding methods. However, the performance of SAG flooding is restricted due to instability under high salinity reservoir conditions and excessive surfactant adsorption. One convenient and relatively low-cost option to overcome the limitations and improve the performance of SAG flooding is the use of low salinity water (LSW). In this study, an innovative and effective approach in the form of a low salinity surfactant (LSS) system was developed to suitably enhance the efficacy of immiscible SAG flooding in sandstone reservoir cores. The impact of LSS solutions on various mechanisms responsible for EOR including surface and interfacial tension (IFT), wettability alteration, CO2-foam stability, and surfactant adsorption were investigated. The initial IFT measurements revealed that oil-water IFT could be lowered using low salinity formation water (FW), however a more effective reduction was possible only when surfactants were introduced in such a system to form LSS solutions. Similarly, reductions in the contact angle (from initial 122 degrees to 45 degrees) were achieved with LSS solutions which demonstrated favorable wettability alteration of the reservoir rock from oil-wet to water-wet conditions. Foam stability experiments revealed that the half-life of CO2-foams generated with LSS solutions was appreciably higher, thus indicating the positive impact of low salinity water on foam stability. Additionally, anionic LSS solutions displayed reduced surfactant adsorption behavior onto sandstone cores, whereas for cationic LSS solutions the adsorption values were comparatively higher and exhibited a reverse adsorption trend with decreasing salinity. Finally, core flooding experiments illustrated that significantly higher residual oil could be mobilized and recovered through the tertiary immiscible low salinity surfactant alternating gas/CO2 (LSSAG) flooding. Nearly 23% original oil in place (OOIP) was produced by employing anionic LSS solution as the chemical slug during the LSSAG flooding. However, under similar experimental conditions, LSSAG flooding with cationic LSS solution recovered only about 16 %OOIP despite its comparatively better wettability alteration and IFT performance. In summary, using anionic LSS solutions constitute an effective means to suitably improve the performance of immiscible SAG flooding in sandstone reservoir cores.
NSTL
Elsevier