查看更多>>摘要：Data-driven models are widely used to predict rate of penetration. However, there are still challenges on real-time predictions considering influences of formation properties and bit wear. In this paper, a novel data-driven model is proposed to tackle this problem by combining an attention-based Gated Recurrent Unit network and fully connected neural networks. At first, input features of the model are elaborately selected by physical drilling laws and statistical analyzes. Then, four subnetworks are employed to construct the whole model structure, where formation properties are assessed using well-logging data and bit wear is evaluated by introducing an attention-based Gated Recurrent Unit network. Next, the model is dynamically updated with data streams by implementing the sliding window method to realize real-time predictions. Finally, the model performance is thoroughly analyzed based on ten field drilling datasets after optimizing model hyperparameters using the orthogonal experiment method. Results indicate that the model is accurate and robust to give predictions after training with the first several data streams. Compared with the conventional data-driven models, the proposed model shows great superiority due to the sub-network structure, the Gated Recurrent Unit network, and the attention mechanism. The model proposed herein opens opportunities for real-time prediction of rate of penetration in the field with high accuracy and robustness.
查看更多>>摘要：Mechanical drilling is facing increasing challenges in exploiting energy stored in deep and hard formations. Laser irradiation has emerged as a novel drilling method with a large potential. The mechanisms of laser irradiation for rock removed consist of melting, evaporation, and splashing. In this study, the characteristics of circumferential strain, temperature, hole size, and modified specific energy of shale rock were studied under laser irradiation with different powers, frequencies, and focal lengths. As indicated from the results, the hole diameter showed a significant positive relationship between laser power and laser frequency, whereas the modified specific energy displayed a negative one. The hole depth increased with the increase of the laser power and the decrease of the laser frequency. The focal length significantly impacted the thermal breaking effect exerted by laser irradiation. The hole diameter was minimum at the focal length of 4.0-4.2 mm. With the increase in the focal length, the hole depth increased from 28.6 mm to 35.5 mm and then declined to 21.1 mm, whereas the modified specific energy decreased from 324 kJ/g to 95 kJ/g and then increased to 108 kJ/g. The cracks in irradiated shale were identified under the scanning electron microscope. This study has a certain guiding significance to break rock for drilling deep hard reservoirs.
查看更多>>摘要：The inflow control device/automatic inflow control device (ICD/AICD) water control completion technology can effectively improve the equilibrium of the liquid production profile of horizontal wells and delay the water ridge problem caused by the heel-toe effect and reservoir heterogeneity. The optimal model of water control completion is the theoretical basis for ICD/AICD completion to equilibrate fluid production. Although many optimal models of water control completion have been proposed, most do not fully consider the reservoir and completion characteristics. In this study, a theoretical model for the optimal design of water control completion is established based on the source function and network model, considering the well trajectory, heterogeneity, drilling pollution, and annulus flow. The variation in fluid production in each producing segment of the heterogeneous reservoir was analyzed for different segments and different flow limiting intensities. The results show that water control completion mainly improves liquid production in the middle permeability zone of the overall horizontal well permeability. For reservoirs with strong heterogeneity, increasing the fluid production in the low permeability zone by excessively restricting the production in the high-permeability zone will cause the fluid production in the middle permeability zone to increase sharply and form water ridges. Segmentation can improve the equilibrium of the fluid production profile, but when the permeability difference is large, too many segments will require a large amount of work and segmentation will have little effect on the equilibrium of the fluid production profile. In engineering applications, the optimized design of water control completion should have the goal of increasing fluid production in the middle permeability zone. The research results are helpful in improving the accuracy of the water control completion model and guide field applications.
查看更多>>摘要：Subsea test tree (SSTT) is an essential safety device for the completion testing operations of deepwater extraction of oil, natural gas, and natural gas hydrate. During the implementation of the emergency release procedure of the SSTT, the coiled tubing or steel wire running in it must be quickly and effectively sheared by its ball valve mechanism. Therefore, clearly revealing the shearing mechanism and accurately evaluating the shearing performance of the ball valve mechanism is essential for maximizing the safety performance of SSTT operation. The finite element numerical simulation method established a dynamic shear model of the SSTT's ball valve under different working conditions and structural parameters to clarify the influencing factors and laws of the ball valve shearing performance. The results of numerical simulation model agree well with the laboratory tests, verifying the scientific validity and accuracy of the numerical simulation method and the generated model. Further, the SSTT's shearing process under different working conditions and geometry was calculated based on the method and model mentioned above. It shows that the tension of coiled tubing is greater, the required of shear moment is smaller. The internal pressure lead to more difficult shearing conditions. In the eccentric position, the ball valve was subjected to a reaction force moment perpendicular to the rotation direction of the ball valve. The larger the ball valve diameter, the shear force required to shear coiled tubing. The SSTT upper seat Angle also affects shear failure performance, and coiled tubing can be shear at 10°, 30°, and 40° with less shear moment. The minimum shear moment is required when the edge of the shearing ball valve has a 1.5 mm circular chamfering. This study proposes an optimization method to improve the shear fracture performance of ball valves. Moreover, this study provides essential guidelines for the optimal design and application operation on the SSTT's ball-valve mechanism.
查看更多>>摘要：Gaseated underbalanced drilling is an attractive choice for horizontal drilling in unconventional reservoirs. However, mud pulse telemetry usually fails in gaseated systems. In this study, an overview of mud pulse telemetry in gaseated drilling was first given for better understanding the current state of the art. Then, factors influencing pulse attenuation in compressible drilling fluids were discussed. Subsequently, a novel method to improve mud pulse telemetry in gaseated drilling were developed. Intermittent gas injection was first developed as a main solution, which refers to pumping only drilling fluids for a while when taking surveys. A model for determining the optimal duration for stopping the gas injection was also proposed, which is critical and must be optimized to allow both telemetry use and underbalance. As another sub method, a gas-liquid mixer was designed to overcome the nonuniform mixing phenomenon in the standpipe. which is also a potential factor in telemetry failure. Flow restrictor and lowering operating frequencies as the other two sub methods were also recommended. Finally, case studies and efficacy analysis were conducted to evaluate these sub-methods. The method of intermittent gas injection was applied in one case. The maximum gas injection rate allowed by acceptable telemetry was raised from 6 m~3 min~(-1) to 12 m~3 min~(-1), which demonstrates the feasibility of the method. Another case showed that the gas-liquid mixer enhanced the detected signal amplitude from 0.0033 MPa to 0.01 MPa, which obtained successful decoding. The results also show that the continuous wave mud pulse telemetry tool has more advantages than the positive pulse systems for mud telemetry in gaseated drilling. The results of efficacy analysis show that flow restrictor and lowering operating frequencies also can enhance mud pulse telemetry performance in gaseated drilling.
Luana B. FurtadoR.C. NascimentoFabio J.F.S. Henrique
13页
查看更多>>摘要：Mild carbon steel is widely used in construction materials owing to its relatively low price, ease of manufacture and high tensile strength. When it is subjected to an aggressive environment, the use of efficient corrosion inhibitors is required. The offshore oil and gas industry apply well stimulation techniques employing strong acids (5-35 wt%), which severely damage metallic structures. Conventional inhibitors may result in environmental and human health problems. In order to avoid that, green compounds have been widely investigated. However in certain applications, such as materials for offshore installations, protection is afforded by multi-component formulations. The synergistic effect of formulations is achieved by the active compounds, intensifiers, surfactants and solvents. Thus the performance of three Schiff bases synthesized from vanillin, a green aldehyde, and aromatic amines was investigated in corrosion inhibition of carbon steel. Weight loss measurements were made in 2 M and 15% HC1 over a 313K-353K temperature range in concentrations between 0.4%wt./v and 1.0%wt./v. Effects of binary and ternary mixtures in 15% HC1 revealed an increased efficiency for isolated inhibitors at higher concentrations. The addition of potassium iodide enhanced efficiency to 97.78% in 15% HC1 at 333 K. Electrochemical tests indicated mixed-type inhibitors. Surface analysis confirmed the presence of a protective film as well as reduced carbon steel roughness. Density-functional theory (DFT) calculations revealed the effects of a substituent on structural and electronic properties in the neutral and acid phases. The role of a sulfur atom in preventing corrosion was also addressed by DFT calculations.
查看更多>>摘要：A series of hyperbranched polyethyleneimine (h-PEI) functioned with terminal amine groups is synthesized to remove oil from O/W emulsion. The demulsifier dehydration rate of h-PEI is systematically evaluated with the subsidiary facilities of DLS analysis, digital tensiometer and UV-vis spectrophotometer. The results indicate that h-PEI demulsifier displays satisfactory demulsification (the oil removal rate >90%) with small dosage (< 80 mg L~(-1)) and short settling time (< 30 min). The relatively short equilibrium time and great demulsification are ascribed to the amine groups and the molecular weight. On one hand, the hyperbranched macromolecules with amine groups can rapidly diffuse and adsorb to the oil-water interface, on the other hand, the molecules with adequate molecular weight are apt to flocculate, coalesce oil droplets, and then obtain high-efficient demulsification. The exceptional demulsification performance of h-PEI exhibits a potential role application in industrial water treatment or the petroleum demulsification industry.
查看更多>>摘要：At present, the technology of carbon dioxide flooding shale gas is a hot topic for scholars. The numerical simulation of shale gas driven by carbon dioxide is inseparable from the accurate understanding of gas percolation mechanism and the construction of two-component gas motion equation. During the flooding process, the gas apparent permeability and the Knudsen number both change with time and space. However, this has not been fully discussed in previous studies. In this paper, the percolation mechanisms of two-component gas are discussed. On this basis, the calculation formula of Knudsen number in porous media is modified, and the transport equation of two-component gas is established. According to the derivation of apparent permeability, the two-component gas apparent permeability model is deduced. Then, the correction effect of Knudsen number and the related properties of two-component apparent permeability are analyzed. The results show that: (1) the effect of Knudsen number correction is significant at low pressure. Under high pressure, that is, when the pressure is greater than 10 MPa, the effect can be ignored; (2) the effect of Knudsen number correction is mainly significant in the range of medium pores, which is generally 10 nm-60 nm. And the peak value range decreases with the increase of pressure; (3) for the relative component apparent permeability curve, it has the properties of both relative permeability and apparent permeability. Based on the data in this paper, for the pressure change, it can be concluded that the maximum change rate of methane is 47.79% and that of carbon dioxide is 51.36%. For the change of pore size, it can be concluded that the maximum change rate of methane is 223.45% and that of carbon dioxide is 106.19%. It can be shown that the relative permeability of carbon dioxide is sensitive to pressure and the relative permeability of methane is sensitive to pore size.
查看更多>>摘要：This study contains a thorough isotopic and molecular characterization of a series of thirteen (13) gas samples and six (6) liquid hydrocarbons produced from late Miocene reservoirs in the offshore Progreso Basin (SW Ecuador), along with Rock-Eval and petrographic analyses of sixty-two (62) rock samples from the area. The principal aim of this research work is to investigate the geochemistry of hydrocarbon fluids and sedimentary rocks in the area of the Amistad field to determine the origin of the studied wet gases. Potential source rocks in the Amistad stratigraphic section are immature and have no oil-generating capability, except for the early Miocene Dos Bocas Formation. Studied low-boiling condensates have similar gas chromatographic fingerprints while their compound-specific isotopic analyses of lower diamondoids (CSIA-D) indicate an oil-source correlation between them and Dos Bocas extracts. Sampled gases are mainly methane of biogenic origin except for that from the Delfin B-17X well, which might represent the thermogenic end-member gas signature of the Amistad gases. Results suggest a complex hydrocarbon filling history with multiple charges of thermogenic gas and hydrocarbons generated from the distal deltaic Dos Bocas source rocks followed by biodegradation, leakage and partial displacement by biogenic methane due to the uplifting of the Amistad structure. The Amistad gases form three homogeneous groups located in the southern, central and northern parts of the Progreso reservoir, although the geological segmentation of it into compartments cannot be clearly identified.
Daniel Asante OtchereBennet Nii Tackie-OtooMohammad Abdalla Ayoub Mohammad
16页
查看更多>>摘要：Seismic fault interpretation is a crucial and indispensable step in reservoir exploration that requires substantial time. As a result, much research has been dedicated to applying deep learning in this venture. Deep learning has shown significant progress in the identification of seismic faults. However, its applicability has been hindered given the lack of appropriate labelled fault data and poor seismic imaging. The deep convolutional neural network (DCNN) employed in this study is a cutting-edge deep learning technique for image improvement and identification. In this study, detecting seismic faults and improving seismic imaging using a pre-trained DCNN is proposed using the Groningen field that has complexity in accurately imaging sub-salt geological structures as a case study. The presence of salt in the field causes wave attenuation. The fault mapping procedure is considered a segmentation of the 3D seismic problem and trains an encoder-decoder architecture, using a Deep Residual U-net, to generate a fault probability volume. A decent fault prediction result is achieved on the Groningen seismic volume. The next step of this study involved seismic data conditioning, where DCNN is applied to denoise volumes to improve visualisation, significantly below the salt structure. The DCNN, when used to improve seismic imaging, achieved a signal-to-noise ratio (SNR) of 30.2, which is almost quadruple that of the original volume. Faults were mapped on the conditioned volume using DCNN, resulting in an improved seismic fault probability volume. This technique achieved distinctively interpreted faults illustrating the significant improvements DCNN brings to the seismic imaging process. In interpreting new seismic volumes with poor imaging and low signal-to-noise ratio, caused by a change in seismic frequency and amplitude propagating through an attenuating medium like the Groningen field, researchers and geophysicists may apply the DCNN for volume conditioning before mapping seismic faults using neural networks.
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