Lu, Chuan (Department of Civil and Environmental Engineering, University of Alberta) | Brandl, Jakob (Department of Civil and Environmental Engineering, University of Alberta) | Deisman, Nathan (Department of Civil and Environmental Engineering, University of Alberta) | Chalaturnyk, Richard (Department of Civil and Environmental Engineering, University of Alberta)
In this study, a novel experimental system has been developed for static and dynamic elastic properties measurements at seismic frequencies under anisotropic stress and shear deformation conditions. This system focuses on static and seismic range frequencies dynamic (0.1 Hz to 20 Hz) elastic deformation properties of poorly consolidated oil sands and highly overconsolidated (clay) shales. The main body of the experimental system is a computer control servo-hydraulic system. A pair of laser displacement sensors measure nanometer scale displacement during the dynamic tests. A coarse scale and fine scale load cell system was developed for measuring force with high precision during dynamic testing. A novel triaxial cell for use with the loading system was also developed to simulate the reservoir stress and pore pressure condition during static and dynamic testing and allows permeability to be measured during testing. The loading system, dual load cell calibration procedure and results, and results for acrylic and 3D printed sand specimens are presented. The stable and reasonable results demonstrate the capacity of the new experimental system.
A sizeable portion of the Athabasca oil sand reservoir is classified as Inclined Heterolithic Stratification lithosomes (IHSs). However, due to the significant heterogeneity of IHSs and the minimal experimental studies on them, their hydro-geomechanical properties are relatively unknown. The main objectives of this study are investigating the geomechanical constitutive behavior of IHSs and linking their geological and mechanical characteristics to their hydraulic behavior to estimate the permeability evolution of IHSs during a Steam Assisted Gravity Drainage (SAGD) operation. To that end, a detailed methodology for reconstitution of analog IHS specimens was developed, and a microscopic comparative study was conducted between analog and in situ IHS samples. The SAGD-induced stress paths were experimentally simulated by running isotropic cyclic consolidation and drained triaxial shearing tests on analog IHSs. Both series of experiments were performed in conjunction with permeability tests at different strain levels, flow rates, and stress states. Additionally, an analog sample with bioturbation was tested to examine the hydro-geomechanical effects of bioturbation. Finally, the hydro-mechanical characteristics of analog IHS were compared with its constituent layers (sand and mud).
The microscopic study showed that the layers’ integration and grain size distribution are similar in analog and in-situ IHS specimens. The results also revealed that geomechanical properties of IHSs, such as shear strength, bulk compressibility, Young's modulus, and dilation angle, are stress state dependent. In other words, elevating confining pressure could significantly increase the strength and elastic modulus of a sample, while decreasing the compressibility and dilation angle. In contrast, the friction angle and Poisson's ratio are not very sensitive to changes in the isotropic confining stress. An important finding of this study is that the effect of an IHS sample's volume change on permeability is contingent on the stress state and stress path. Volume change during isotropic unloading-reloading resulted in permeability increases and sample dilation during compression shearing resulted in permeability decreases, especially at high effective confining stresses. Moreover, the tests revealed that the existence of bioturbation dramatically improves permeability of IHSs in comparison to equivalent non-bioturbated specimens but has negligible effects on its mechanical properties, which remain similar to non-bioturbated specimens. The results also showed that bioturbation has minimal impact on permeability changes during shearing. Lastly, experimental correlations were developed for each of the parameters mentioned above.
For the first time, specialized experimental protocols have been developed that guide the infrastructure and processes required to reconstitute analog IHS specimens and conduct geomechanical testing on them. This study also delivered fundamental constitutive data to better understand the geomechanical behavior of IHS reservoir and its permeability evolution during the in-situ recovery processes. Such data can be used to accurately capture the reservoir behavior and increase the efficiency of SAGD operations in IHS reservoirs.
A new approach that uses logs derived from wireline and surface drilling data to extract an interface proxy is presented and illustrated in the Montney. The derived interface proxy logs are propagated in the entire reservoir volume using artificial intelligence-based reservoir modeling. Blind wells confirm the ability to predict the interface proxy at any reservoir location. The derived interface proxy propagated in 3D was validated with moment tensor showing that the microseismic shear plane events occur mainly where the presence of the interfaces is the highest.
Using the derived interface proxy as an input, the Material Point Method (MPM) and Anisotropic Damage Mechanics (ADaM) are used to solve the geomechanical modeling of a hydraulic fracture propagating in a layered medium containing any type of interfaces including the weak interfaces. The geomechanical simulation confirms the major impact these weak interfaces could have on the fracture height growth.
The geomechanical analysis confirmed the importance of mapping in 3D the interfaces and modeling their effects in an accurate manner to better capture their effect on fracture height growth and the resulting proppant placement. The application of the new geomechanical workflow was illustrated on two Montney wells and was able to provide some explanation on their production differences that could be attributed to interfaces.
There is an ongoing paradigm shift in the processes and technologies employed in making field development decisions in unconventional reservoirs. Expensive trial and error exercises in multiple reservoirs have returned the verdict: there is no single prescribed treatment for a given reservoir, which always maximizes production and eliminates risk of frac hits and well interferences. In many situations, lateral growth of hydraulic fractures has been the major concern amongst operators, but as the economics of unconventional production shift, and the industry moves to more wine-racking and cube development plans, it has become abundantly clear that current hydraulic fracturing design software have multiple shortcomings such as not being able to fully account for natural fractures and predicting the subsequent frac-complexity as well as including the critical effects of weak interfaces. One of the consequences of this poor representation of the physics occurring during hydraulic fracturing of unconventional wells is the overprediction of hydraulic fracture heights. All commonly used industry frac design software are neither able to predict microseismicity to prove their ability to reproduce the observed frac complexity nor capable of including the effects of weak interfaces, or bedding and laminations (geologically speaking) on hydraulic fracture propagations in the vertical direction. Since microseismicity has been successfully predicted to capture the lateral stress gradients created by the natural fractures, the focus in this study is quantifying at any well the characteristics of the interfaces and their impact on the fracture height. Geomechanical logs derived from commonly available surface drilling data are used to capture zones of high interface potential and their characteristics. The resulting interface positions and their mechanical properties are input in a geomechanical simulator using the Material Point Method (MPM) to simulate the effect of the weak interfaces on hydraulic fracture height growth. These simulations provide the necessary information required by frac design software that now can incorporate not only the lateral stress gradients created by the natural fractures but also the vertical complex effects created by the weak interfaces. The results of this fast-practical decoupled workflow are a better estimate of the spacing needed for wine-rack systems and more realistic fracture geometries inputs to fluid flow models which can provide realistic geometries of depletion profiles affecting well interference potentials driven by production.
Wang, Yefei (Key Laboratory of Unconventional Oil & Gas Development, China University of Petroleum East China, Ministry of Education, P. R. China, School of Petroleum Engineering, China University of Petroleum East China) | Yang, Zhen (Key Laboratory of Unconventional Oil & Gas Development, China University of Petroleum East China, Ministry of Education, P. R. China, School of Petroleum Engineering, China University of Petroleum East China) | Wang, Renzhuo (Key Laboratory of Unconventional Oil & Gas Development, China University of Petroleum East China, Ministry of Education, P. R. China, School of Petroleum Engineering, China University of Petroleum East China) | Chen, Wuhua (Key Laboratory of Unconventional Oil & Gas Development, China University of Petroleum East China, Ministry of Education, P. R. China, School of Petroleum Engineering, China University of Petroleum East China) | Ding, Mingchen (Key Laboratory of Unconventional Oil & Gas Development, China University of Petroleum East China, Ministry of Education, P. R. China, School of Petroleum Engineering, China University of Petroleum East China) | Zhan, Fengtao (College of Science, China University of Petroleum East China) | Hou, Baofeng (School of Petroleum Engineering, Yangtze University)
A novel indolizine derivative inhibitor for acidization was introduced. It could exhibit effective corrosion inhibition at a much lower concentration without propargyl alcohol and shows economic and environmental advantages. From quinoline, benzyl chloride, and chloroacetic acid, two indolizine derivatives were prepared under certain conditions. These inhibitive indolizine derivatives were both synthesised from benzyl quinoline chloride (BQC), which one of the conventional quaternary ammonium corrosion inhibitors used for acidising. The target compound was purified and instrumental analysis methods including elemental analysis, high-resolution mass spectrometry (HRMS), and NMR were used to characterise the chemical structure. The inhibition performance of the indolizine derivatives in 15 wt.% HCl, 20 wt.% HCl, and mud acid (12%HCl + 3%HF) for N80 steel was investigated by weight loss measurement, electrochemical method (potentiodynamic polarization and EIS), and SEM surface morphology assessment.
When 0.1 wt.% indolizine derivative was added, the inhibition efficiency of N80 steel in 15 wt.% HCl at 90 °C increased to 98.8 % and 99.1 % respectively without the synergistic effect of propargyl alcohol: however, in terms of BQC, even at a dosage of 1.0 wt.%, the inhibition efficiency of N80 steel only reached 83.3 % under the same conditions. The novel derivative could impart an improved corrosion resistance effect. Compared with BQC, there are more active adsorption sites in the derivative and therefore the inhibitor could be better fastened to the steel surface. The firmly adsorbed inhibitors would thereby prevent the metal surface from making contact with H+ ions and finally increase the inhibitory effect. As a high-efficiency corrosion inhibitor, the novel indolizine derivatives may offer a new strategy for corrosion protection in acidising.
Wang, Renzhuo (Key Laboratory of Unconventional Oil & Gas Development, Shandong Key Laboratory of Oilfield Chemistry, School of Petroleum Engineering, School of Petroleum Engineering ,China University of Petroleum, East China, Ministry of Education) | Yang, Zhen (Key Laboratory of Unconventional Oil & Gas Development, Shandong Key Laboratory of Oilfield Chemistry, School of Petroleum Engineering, School of Petroleum Engineering ,China University of Petroleum, East China, Ministry of Education) | Chen, Wuhua (Key Laboratory of Unconventional Oil & Gas Development, Shandong Key Laboratory of Oilfield Chemistry, School of Petroleum Engineering, School of Petroleum Engineering ,China University of Petroleum, East China, Ministry of Education) | Wang, Yefei (Key Laboratory of Unconventional Oil & Gas Development, Shandong Key Laboratory of Oilfield Chemistry, School of Petroleum Engineering, School of Petroleum Engineering ,China University of Petroleum, East China, Ministry of Education) | Ding, Mingchen (Key Laboratory of Unconventional Oil & Gas Development, Shandong Key Laboratory of Oilfield Chemistry, School of Petroleum Engineering, School of Petroleum Engineering ,China University of Petroleum, East China, Ministry of Education) | Zhan, Fengtao (College of Science, China University of Petroleum)
Among the numerous corrosion inhibitors for acidizing, the propargyl alcohol, with great expense and high toxicity, is often added as an important synergistic component. In this work, novel indolizine derivative high-effective inhibitor for acidizing was introduced. The indolizine derivative could exhibit an excellent protection performance at a much lower concentration without the synergism of the poisonous propargyl alcohol. The two inhibitive indolizine derivatives in this paper were synthesized easily from Benzyl Quinolinium Chloride (BQC, known as the a commonly used key component of acidizing inhibitor) via 1,3-dipolar cycloaddition reaction. The indolizine derivatives were purified by the column chromatography and the structure were characterized by NMR and elementary analysis etc.
The inhibition performance of the BQC, propargyl alcohol and the indolizine derivatives in 15 wt.% HCl and 20 wt.% HCl for N80 steel was investigated by weight loss test and potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The conclusion obtained from the electrochemical tests is in accordance with the results of gravimetric test. It is amazing to notice that the derivative could exhibit a much better anti-corrosion performance than its precursor BQC and propargyl alcohol in the abserence of the poisonous propargyl alcohol.
Compared with BQC, the active adsorption sites are reinforced and strengthed in indolizine derivatives, and therefore, the inhibitor would fasten the steel surface more stronger. The firmly adsorbed inhibitors would prohibit the steel from the contact of acid. Indolizine derivative is presented as a new concept of effective acidizing inhibitor for the first time in this paper. It may offer a new method for the corrosion prevention in acidification engineering.
Wan, Liming (State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum) | Chen, Mian (State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum) | Zhang, Fengshou (Department of Geotechnical Engineering, Tongji University) | Wang, Li (China United Coalbed Methane Co., Ltd.) | Chen, Wangang (China United Coalbed Methane Co., Ltd.)
With the development of unconventional oil and gas resources, the technology of commingling production in coal measure has been studied, which requires us to have a better understanding of the fracture near the wellbore in multi-layers. Previous studies mainly focused on the fracture morphology in a single layer and lack of 3D evolution role of microfracture propagation, so the fracture geometry in multi-layers of the coal seam and microfracture initiation near wellbore were studied in this paper.
In this study, the 3D-lattice model was used to simulate the 3D dynamic hydraulic fracture morphology near the wellbore in multi-layered coal based on XSite simulator, and the spiral perforation position was mainly studied. To verify the numerical simulation, the true tri-axial test system was implied for fracturing simulation experiments on the combination of coal, sandstone and limestone outcrops. The perforation position was changed to analyze the fracture morphology near the wellbore. Besides, the 3D scanning technology and the fracturing curve were used to study the fracture characters. As a result, the fracture morphologies near the wellbore in different perforation positions were studied.
The numerical simulation results showed that the microfracture evolution process in spiral perforation can be divided into three stages, (a) Stage 1: the vertical microfracture bands develop along the perforation hole; (b) stage 2: micro-annulus fracture forms around the wellbore; (c) stage 3: fractures break through along the perforation holes perpendicular to the minimum in-situ stress. The cleats and the natural fractures dominated the fracture initiation geometry when perforating in coal. The secondary branch fractures and the stepped fractures were the main characters in coal. Sandstone was a good barrier layer for the coal seam in fracturing, and the fracture in coal was easy to break through the limestone layer. When fracture initiated in coal layer, the fracture near the wellbore was complex with many secondary fractures, and the fracture surface was rough with poor continuity; when initiated in both sandstone and coal layers simultaneously, the main fracture developed quickly in coal and the smooth fracture surface formed near the wellbore.
The results of laboratory experiments were in good agreement with numerical simulation. The 3D evolution role of microfracture near wellbore could give a deep understanding of fracture complexity in near-wellbore area in coal. The experiments considered the actual formation combination, and the results of multi-layer fracturing could give a good guidance for field perforation optimization in the commingling of coal measure strata.
Ernens, Dennis (Shell Global Solutions International BV, University of Twente) | Peréz-Ràfols, Francesc (Luleå University of Technology) | Hoecke, Dennis Van (OCAS NV) | Roijmans, Roel F. H. (Shell Global Solutions International BV) | Riet, Egbert J. van (Shell Global Solutions International BV) | Voorde, John Vande (OCAS NV) | Almqvist, Andreas (Luleå University of Technology) | Rooij, Matthijn Bas de (University of Twente) | Roggeband, Serge Mathieu (Shell Global Solutions International BV) | Haaften, Willem Maarten Van (Shell Global Solutions International BV) | Vanderschueren, Marc (OCAS NV) | Thibaux, Phillipe (OCAS NV) | Pasaribu, Henry Rihard (Shell Global Solutions International BV)
Metal-to-metal seals are used in connections of casing in oil and gas wells. This paper describes the mechanisms of sealing of metal-to-metal seals as investigated using an experimental set-up and a sealability model. Experiments were conducted for a variety of thread compounds and applied pin/box surface coatings. The results were used to validate a numerical model for sealability. The stochastic model couples a contact mechanics model with a flow model and takes the influence of all the surface topography features into account. Once validated, the model was used together with the experimental results to explain the sealing mechanisms of metal-to-metal seals.
The sealing configuration is a face seal with an R=80 mm round-off radius pressing against a flat. The face seal specimens were manufactured from P110 tubing. The used test set-up is designed for investigating only the metal-to-metal seal of the connection. The set-up can carry out rotary sliding under constant load to simulate surface evolution during make-up and subsequently perform a leakage test. The sealing limit is determined by applying 700 bar fluid pressure and then gradually reducing the normal force until leakage is observed. The data is subsequently used to validate a previously published model.
The results indicate a strong dependence of the type of thread compound used on the onset of leakage. The thread compound affects the amount of wear and thus changes the surface topography of the interacting surfaces. It is shown that the sealability model is capable to predict the onset of leakage within the experimental accuracy. The model shows further that certain surface topographical features improve the sealing performance. Namely, a turned against a flat surface topography leads to highly localized contact areas, which in turn yields the best sealing performance.
The combination of experimental data with the validated model leads to much deeper insights for the sealing mechanisms than what could be obtained using either on their own.
Müller, Nathalie (Fraunhofer-Institut für Windenergie und Energiesystemtechnik (IWES)) | Kraemer, Peter (University of Siegen) | Leduc, Dominique (Research Institute of Civil Engineering and Mechanics (GeM)) | Schoefs, Franck (Research Institute of Civil Engineering and Mechanics (GeM))
A fatigue test has been conducted on a large-scale offshore wind turbine grouted connection specimen at the Leibniz University of Hannover. For detecting damages in the grouted joint, a structural health monitoring (SHM) system based on fiber optic sensor-type fiber Bragg grating (FBG) has been implemented. By extracting the features of the FBG signal responses using the Wigner–Ville distribution (WVD) and one of its marginal properties, the energy spectral density (ESD), it is possible to detect the occurrence and the global severity of the damage. Some information about the local severity of the damage has also been obtained.
The grouted connection consists of the high-performance grout-filled space between the two structural steel components of respectively the sleeve and the pile of offshore wind turbines (OWTs). For monopile OWTs, it is located around the water level between the transition piece and the pile, whereas for jacket and tripod OWTs, it is located just above the seabed, between substructure and foundation pile. While grouted joints for monopiles are exposed to bending moments, grouted joints for latticed substructures (tripods and jackets) are exposed to predominant axial loadings and low torsional moments (Schaumann and Böker, 2005; Schaumann, Lochte-Holtgreven et al., 2010). It is a critical structural part of OWTs. In 2009–2010, engineers reported grouted connection failures causing slight and progressive settlement of turbines. The problem affected approximately 600 of the 988 monopile wind turbines in the North Sea, requiring further investigations concerning the design of the grouted connection (Rajgor, 2012). Since then, two grouted connection designs reducing the axial forces in this area have been recommended by Det Norske Veritas (2014): using a conical grouted connection (first design) or a tubular connection with shear keys (second design).
Selker, Ruud (INTECSEA) | Liu, Ping (INTECSEA) | Jurdik, Erich (South Stream Transport BV) | Chaudhuri, Jay (South Stream Transport BV) | Fonzo, Andrea (RINA Consulting-Centro Sviluppo Materiali) | di Biagio, Massimo (RINA Consulting-Centro Sviluppo Materiali)
S-Lay installation of inline buckle arrestors in deep water can introduce plastic strain to girth welds. The welds are repeatedly loaded by large-strain cycles when traversing the stinger. A material-testing program was launched to assess the impact of this load sequence on the welds’ integrity. It is essential to establish the correct mechanism of crack growth caused by a limited number of sequential large-strain cycles. Segment specimens with increased specimen “daylight” length were tested. Fracture morphologies of ductile tearing and fatigue growth were distinguished; ductile tearing was identified only for the first load cycle, whereas subsequent cycles were dominated by fatigue crack growth.
The TurkStream Offshore Pipeline was developed by South Stream Transport BV (SSTTBV). It is a major gas-transmission system that currently comprises two pipeline strings installed in up to 2,200 m water depth, connecting large gas reservoirs in Russia to the Turkish gas-transportation network through the Black Sea. The system currently has a capacity to transport 31.5 bcm of natural gas annually over a distance of more than 900 km. The pipeline’s outer diameter (D) is 32 inches, and its wall thickness (t) is 39 mm. Material grade is DNV SAWL (submerged arc-welded longitudinal) 450 with supplementary requirement F, D, U, and (light) S according to offshore standard DNV-OSF101 (Det Norske Veritas, 2010) plus project-specific modifications. Pipe joints are produced by UOE (U-ing, O-ing and expansion) and JCOE (J-ing, C-ing, O-ing and expansion) pipe-forming methods. Ultra-deep water in combination with the large pipeline diameter makes this project one of the most challenging pipeline projects ever, pushing the boundaries of the industry. The first portion of the pipeline was installed in 2017–2018.
Shibayama, Atsushi (Central Research Institute of Electric Power Industry) | Miyagawa, Yoshinori (Central Research Institute of Electric Power Industry) | Kihara, Naoto (Central Research Institute of Electric Power Industry) | Kaida, Hideki (Central Research Institute of Electric Power Industry)
The damages of the gigantic tsunami that followed the 2011 Great East Japan Earthquake were confirmed on reinforced concrete (RC) structures (Nandasena et al., 2012). Moreover, the damages caused by the tsunami debris collision were confirmed in addition to the damages caused by only the tsunami. Therefore, it is important to clarify the response characteristics of the structure subjected to the tsunami wave force and collision force, and to establish a response evaluation method by numerical analysis. However, the response characteristics of RC structures subjected to two external forces with significantly different timings of actions--namely, wave pressure and collision forces--have not been clarified. Furthermore, to assess the responses of RC structures using numerical analysis, the two different types of superimposing external forces must be considered. However, the applicability of numerical analysis under such external force conditions has not been sufficiently verified. In this research, a large-scale debris collision experiment was first conducted to experimentally investigate the response of an RC vertical wall subjected to the wave pressure and debris collision forces. Next, a reproducibility analysis of the experiment was performed with nonlinear finite element analysis to examine the adaptability of the finite element analysis.