Shi, Xiaoyan (CNPC Engineering Technology R&D Co. Ltd) | Zhou, Yingcao (CNPC Engineering Technology R&D Co. Ltd) | Zhao, Qing (CNPC Engineering Technology R&D Co. Ltd) | Jiang, Hongwei (CNPC Engineering Technology R&D Co. Ltd) | Zhao, Liping (CNPC Engineering Technology R&D Co. Ltd) | Liu, Yong (Petro China Tarim Oilfield Company) | Yang, Guang (CNPC Engineering Technology R&D Co. Ltd)
Influx and loss are the two most common downhole complexities. They not only cause the reservoir damage, increase the exploration cost, reduce the drilling efficiency; but also induce major malignancy. Therefore accurate and early detection of influx and loss during drilling is of great significance. Traditional influx and loss detection methods have the shortcoming of monitoring time lagging and high costs. As the rapid development of artificial intelligence techniques, researchers start to detect influx and loss using artificial intelligence method. This work adopted two machine learning algorithms(Random forests and Support vector machine) according to their characteristics to detect influx and loss during drilling in real-time. The detection methods includes four steps: 1) Generating raw influx/loss raw data set by combining real-time drilling data and drilling history data; 2) Pre-processing raw data set to obtain training data set; 3) Training classification model of random forests and SVM by training data set and algorithms; 4) Predicting influx/loss by the trained model according to the new real-time data. The case study shows that influx and loss can be detected accurately in early stage by both random forests method and SVM method after proper pre-processing the raw data and optimizing algorithm parameters. The detection accuracy of the sample data from four wells exceeds 90%. This work demonstrate a new way to detect influx and loss by utilizing huge drilling data and machine-learning algorithms, and the detection results are satisfying.
Multicomponent joint inversion is an important technique for reservoir prediction using PP and PS seismic data. The addition of PS data is helpful to solve the problem of multiplicity and increase the precision of reservoir prediction. Based on 3D multicomponent seismic data of M area in Canada, the logging response characteristics of the reservoir are analyzed and the sensitive parameters are optimized. The PP and PS joint inversion, characteristic curve inversion and lithofacies probability simulation are integrated to increase the precision of reservoir prediction gradually. The application results show that, due to the reservoir prediction based on joint inversion, the top and bottom interface of oil sands reservoir and the distribution of interbed are described in detail. And important geophysical prospecting results are provided for oil sands development in this area.
Presentation Date: Monday, October 15, 2018
Start Time: 1:50:00 PM
Location: 213A (Anaheim Convention Center)
Presentation Type: Oral
A two-dimensional (2-D) numerical model is applied to study the wave reflection performance of perforated caisson breakwaters. The numerical model adopts a volume of fluid (VOF) method to track free surface and simulates the turbulent flow by using Reynolds Average Navier-Stokes (RANS) and k-ε turbulence model equations. The numerical results for the reflection coefficients of perforated caissons are in good agreement with the experimental data in literature, which means that the present numerical model can well estimate the hydrodynamic performance of complicated perforated thin wall structures. Numerical examples show that when the caisson porosity is fixed, the slit width in the perforated front wall has no significant influence on the reflection coefficient of perforated caisson breakwater. The effects of the slit width and the relative wave chamber width on the flow velocity and the turbulence kinetic energy are also discussed. It is found that the fluid flow through the perforated wall is in a form of jets and the turbulence kinetic energy is mainly concentrated around the region of the wave chamber.
A perforated caisson breakwater, containing a chamber between a perforated front wall and an impermeable back wall, has a good capability of reducing wave reflection and wave forces. The conception of the perforated wall breakwater was initially proposed by Jarlan (1961). Since then, research on wave interactions with perforated caisson structures has been ongoing. The relevant studies on the hydraulic performance of various types of perforated breakwaters have been reviewed by Huang et al. (2011).
Tanimoto et al. (1976) carried out earlier model tests to study the reflection of irregular waves by the perforated caisson breakwater. Kondo (1979) presented an analytical approach to estimate the reflection coefficient of a two-chamber perforated wall breakwater. Tanimoto and Yoshimoto (1982 ) theoretically and experimentally studied the reflection coefficient of a partially perforated caisson breakwater. Fugazza and Natale (1992) applied the potential flow theory to examine the reflection coefficients of perforated breakwater with multiple wave chambers. Using the Galerkin-eigenfunction method, Suh and Park (1995) developed an analytical model to predict the reflection coefficient of perforated caisson breakwater with a rubble mound foundation. Suh et al. (2001) theoretically investigated the reflection characteristics of irregular waves on perforated caisson breakwater. Ti et al. (2002) and Ti et al. (2003) used the matched eigenfunction expansion method to examine the oblique wave reflection by single-chamber and doublechamber perforated caisson breakwaters, respectively. Takahashi et al. (2003) employed a numerical technique to investigate the reflection coefficient of perforated caissons. Liu et al. (2007) studied the reflection coefficients of regular and irregular waves by a partially perforated caisson breakwater with a rock filled core. Lee and Shin (2014) earned out a three-dimensional model test to investigate the reflection coefficient of the perforated wall structure. Recently, Neelamani et al. (2017) carried out experimental tests to assess the wave reflection characteristics of a Jarlan-type breakwater with slotted walls.
This paper concerns the behaviour of regular waves interacting with a smooth submerged breakwater. A series of experiments was carried out and was used to compare with the numerical results based upon a RNG k-ε turbulence model and Volume of Fluid (VOF), and they agreed well with each other. The effect of different submergence on wave surface profiles and the spatial evolution characteristic of the harmonics waves are investigated using the numerical results. In addition, the flow field and turbulence characteristics are exploded when the waves go cross the breakwater. It was found that the wave transmission coefficient of the submerged breakwater increases with the increase of the relative submersion depth R/H and incident wave period, respectively. However, it decreases with the increase of the wave steepness H/L. Finally, an empirical formula was conducted to illustrate the wave transmission coefficient relationship with the wave parameters.
As one form of traditional breakwaters, the submerged breakwater (SB) is widely used in coastal regions to protect the harbor and costal area, and it has received a great deal of attention (Karmakar and Guedes Soares, 2015; Liu and Li, 2011). When waves cross the SB, the wavebreaking process and nonlinear interaction between the wave spectrum components occur. Nonlinear interactions between wave components cause a wave energy transfer from wave spectrum primary harmonics to higher harmonics (Brossard and Chagdali, 2001; Carevic et al., 2013). As a consequence, the mean wave periods decrease by approximately 60% in relation to the incoming mean wave periods due to SB, as shown by Tanimoto et al. (1987). The amount of transferred energy depends on the incoming wave parameters, breakwater geometry and water depth. Beji and Battjes (1993) observed high-frequency wave energy amplifications as waves propagate over a SB in a laboratory experiment. It was found that bound harmonics are amplified during the shoaling process and released in the deeper water region after SB. Masselink (1998) illustrated that when relatively long waves propagate over submerged obstacles, they may decompose into shorter components referred to as secondary waves. The generation of secondary waves on a barred beach was investigated using field measured data, and a decomposition of a breaking incident swell into several smaller and shorter waves was observed in the deeper water after SB.
This work presents an energy balance analysis for the wave resonance problem encountered in the gap formed by a fixed barge placed in front of a vertical wall. The numerical examinations are based on a 2D Smoothed Particles Hydrodynamics (SPH) model. The results, for the free surface elevations in the gap, are firstly validated with experimental data considering different values of wave period (therefore ranging in the resonant and non-resonant conditions). Then, the energy analysis is focused to study the wave resonant condition occurring in the narrow gap. The evolutions of the energy components are shown for the overall fluid domain and, successively, for two subregions of the fluid domain: the region in which the waves propagates in the wave flume and the region in which the fixed barge is located. The amount of energy dissipated in the latter region allows for the determination of the hydraulic performances of the fixed barge.
The SPH is a numerical method that is able to accurately describe the dynamic of complex flows. Indeed, as a meshless, Lagrangian, particle method, the SPH can easily track the dynamic of problems in which large deformation and also fragmentation of the free surface take place. Applications of SPH to solve free surface flows are relatively new compared with others computational fluid dynamic solvers. Indeed, the first work in fluid dynamic context dates back to Monaghan (1994) and, after that, the method has been successfully extended and applied to various engineering fields. Applications of SPH and others similar particle based methods to coastal and ocean engineering field regard wave breaking (Monaghan and Kos, 1999; Dalrymple and Rogers, 2006), impacts of tsunami waves on structures (St-Germain et al., 2013; Cunningham et al., 2014), water-slamming problem (Khayyer and Gotoh, 2016), waves interacting with open-piled structures (Gao et al., 2012), waves interacting with breakwaters (Ren et al., 2014; Meringolo et al., 2015; Aristodemo et al., 2015), solitary waves passing over a submerged cylinder (Aristodemo et al., 2017). A study on the applicability of the SPH to analyse wave impacts, based on the DualSPHysics model, has been presented by Altomare et al. (2015), while a review on the applications to coastal engineering field for particles method has been presented in Gotoh and Khayyer (2016) and more recently in Gotoh and Khayyer (2018).
The hydrodynamic performance of multiple partially immersed slotted barriers is analytically studied based on the potential theory. The quadratic pressure drop boundary condition at slotted barriers is adopted, and the matched eigenfunction expansion method with iterative calculations is used to develop the analytical solution for the wave scattering problem. The iterative analytical solution is validated by an independently developed multi-domain boundary element method solution and experimental data in literature. Major factors influencing the reflection coefficient, the transmission coefficient and the energy dissipation coefficient of slotted barriers are clarified. The present solution with high computing efficiency can be used to determine the optimum parameters for slotted barriers in preliminary engineering design.
The immersed barriers have been often used for the coastal and harbor protection. Compared with bottom-standing rubble mound breakwaters and vertical wall breakwaters, the immersed barriers are more economically and environmental friendly in deep water. Since the wave energy is concentrated near the fluid surface, the immersed breakwater can reflect and dissipate wave energy effectively, and offer a good shelter for the leeside region.
Compared with impermeable barriers, slotted/perforated barriers have a better stability and have attracted much attention. The hydrodynamic performance of slotted/perforated barriers can be fast analyzed using potential theory, if a suitable pressure drop (energy loss) condition is introduced on the barrier. Based on the porous medium model of Sollitt and Cross (1973), Yu (1995) developed a linearized pressure drop condition on the perforated barrier, in which the pressure difference between the two sides of the barrier is linear proportional to the fluid velocity across the barrier. This boundary condition has been widely used by many researchers (e.g., Isaacson et al., 1999; Liu et al., 2008; Koraim et al., 2011). Based on the assumption of long wave theory, Mei et al. (1974) developed a quadratic pressure drop condition on perforated barrier in terms of jet through the pores. Bennett et al. (1992) extended the application of Mei’s quadratic pressure drop condition to general wave conditions. Molin and Fourest (1992) also developed a quadratic pressure drop condition on perforated barriers to study wave absorbers in a flume. Recently, Molin and Remy (2015) incorporated the inertial effect term into the Molin’s quadratic pressure drop condition. The beauty of the quadratic pressure drop condition is that the effect of wave height on the wave energy dissipation by the slotted barriers can be directly considered by the mathematical model itself.
In this paper, a numerical model based on OpenFOAM (Open Source Field Operation and Manipulation, an open source CFD code) is used to investigate liquid sloshing in a swaying tank with a submerged horizontal perforated plate (SHPP), which we have experimentally studied before. As a supplement to the previous experimental investigation, the flow characteristics in the tank are numerically analysed. The numerical results of surface elevations in the tank are in good agreement with previous analytical, numerical and experimental results in literature. The optimal parameters of the SHPP for suppressing violent sloshing at both first- and third-order resonant frequencies are determined. The analysis results can give a better understanding on the sloshing suppression mechanism of the SHPP.
Fluid sloshing in partially filled tanks can cause large hydrodynamic loads when the frequency of tank motion is close to the natural frequency of the tank. The inherent energy damping of a sloshing tank without inner structures has been found to be insufficient for suppressing the violent sloshing motion (Fediw et al., 1995; Tait et al., 2004). Various approaches have been proposed to increase the inherent damping of the sloshing tank. It has been found that perforated plates can efficiently dissipate the energy of sloshing meanwhile improve the stability of the tank system (Tait et al., 2005; Faltinsen and Timokha, 2001). Recently, Jin et al. (2014) showed in experimental tests that a SHPP can serve as a good sloshing suppression device in a swaying water tank. But the movement characteristics of the fluid and the energy dissipation mechanism of the SHPP still need to be further clarified.
To understand the energy damping mechanism in a sloshing tank, numerical analysis through CFD (Computer Fluid Dynamic) method may offer great help. Based on numerical simulations, Lee et al. (2007) clarified the effects of the fluid viscosity, density ratio and compressibility on the sloshing loads. Wemmenhove et al. (2015) used a compressible two-phase flow method to simulate the fluid impact in a sloshing tank. Garrido-Mendoza et al. (2015) validated the simulation results of sloshing in a tank using PIV (Particle Image Velocimetry) measurement results. They found that laminar flow assumption can be used to simulate the sloshing movement since the turbulence is not the most important factor in the simulation. Firoozkoohi et al. (2015) used OpenFOAM to examine the fluid motion in the sloshing tank with a vertical perforated plate. The preceding studies have demonstrated the robustness and stability of the numerical method for simulating liquid sloshing.
Perforated caissons, which have the merits of lower reflection coefficient and smaller wave overtopping discharge and wave forces compared to traditional non-perforated caissons, are often used for building vertical coastal and harbor structures. As one of the most important hydraulic responses of coastal structures, wave overtopping must be carefully considered in engineering design. This study examines wave overtopping at perforated caissons for non-breaking waves. Based on experimental data, a modified predictive formula of the mean overtopping discharge for perforated caissons is proposed. The modified predictive formula is valid in a wide range of the relative crest freeboard. This study also demonstrates that the half value of the mean overtopping discharge for impermeable vertical walls predicted by EurOtop formula can be simply adopted as the mean overtopping discharge for perforated caissons with the same relative crest freeboard. The predictive methods proposed in this study should be valuable for engineering design of perforated caissons.
A Jarlan-type perforated caisson involving a perforated front wall, a solid rear wall and a wave-absorbing chamber between them has the merits of lower reflection coefficient and smaller overtopping discharge and wave forces in comparison with a traditional non-perforated caisson (Jarlan, 1961). Thus, perforated caissons have been often used for building vertical breakwaters, seawalls and quay walls. A variety of studies on wave interaction with perforated caissons have been carried out, and the relevant literature reviews have been given by Li et al. (2007), Suh (2009) and Huang et al. (2011). However, most of the studies focused on the reflection coefficient and wave forces on perforated caissons. Studies on wave overtopping at perforated caisson are still not enough.
Liu, Yong (China University of Petroleum, State Key Laboratory of Petroleum Resources and Prospecting, CNPC Key Laboratory of Geophysical Exploration) | Wang, Shangxu (China University of Petroleum, State Key Laboratory of Petroleum Resources and Prospecting, CNPC Key Laboratory of Geophysical Exploration) | Yuan, Sanyi (China University of Petroleum, State Key Laboratory of Petroleum Resources and Prospecting, CNPC Key Laboratory of Geophysical Exploration) | Tian, Nan (CNOOC Research Institute) | Liu, Junzhou (Sinopec Exploration & Production Research Institute)
One important application of time frequency analysis is the identification of channel complex. However, conventional time frequency analysis methods suffer from low resolution which sometimes leads to relative terrible interpretation results. In this paper, a novel time frequency analysis approach called inversion spectral decomposition (ISD) is applied to solve these problems. ISD is proposed via inversion strategy and has a higher resolution. In the identification of channel complex, ISD provides not only more detailed time frequency content in time frequency amplitude spectrum than conventional time frequency analysis methods, but also additional phase information, which gives another perspective to identify channel complex, thus reducing the uncertainty in interpretation. In the test of 3D synthetic data, both Gabor transform and ISD are applied to generate time slices. Gabor transform only identifies the middle section of channel complex while ISD clearly identifies the whole channel complex with legible details. Furthermore, ISD provides additional phase information, further confirming the reliability in interpretation. Finally, ISD is applied to a 3D real data, and exhibits an outstanding performance.
With the development of oil and gas exploration, detecting complex geologic bodies, such as low amplitude structure and the thin layer oil and gas reservoir, has currently become a main target of exploration and development. Channel complex, a common reservoir type and favorable place for oil and gas reservoir in continental basins, can be efficiently identified by spectral decomposition. The key point of spectral decomposition is the selection of timefrequency analysis technique. The short-time Fourier transform (STFT) is widely used to produces a time frequency spectrum. Parktyka (1999) predicted the spatial distribution characteristics of the channel by analyzing various amplitude spectra and phase spectra obtained by the short time Fourier transform (STFT). Marfurt (2009) utilized STFT to analyze thin layer and sedimentary facies.
Xu, Kai (Sinopec Geophysical Research Institute) | Xiao, Pengfei (Sinopec Geophysical Research Institute) | Cao, Huilan (Sinopec Geophysical Research Institute) | Ding, Juan (Sinopec Geophysical Research Institute) | Lin, Zhang (Sinopec Geophysical Research Institute) | Chen, WenShuang (WenShuang China University of Petroleum, East China) | Liu, Yong (China University of Petroleum, East China)
In this paper we discuss a case study of inversion using wide-azimuth data for fracture-cavity characterization of the deep carbonate reservoirs in Tahe Oilfield. The method is based on Chapman's Theory (2003), assuming that the rock is dispersive, also has the dispersion and azimuthal anisotropy properties. In short, dispersion properties are changing with the azimuth. The result of frequency-dependent AVO inversion shows a good correlation with the post-stack coherence properties, and the ellipse-fitted result of dispersion properties also shows a good correlation with the well data. This method has been proved effectively and meaningfully in the carbonate fracture-cavity reservoir prediction.
Chapman (2002) pointed out that the rock's pore space was composed of randomly distributed flat spherical micro-cracks, ball diameter pores and aligned flat spherical fractures. The propagation of seismic wave causes fluid flow in the meso-fractures, micro-cracks and pores, which in turn causes the frequency-dependent anisotropy. P-wave attenuation and dispersion vary with azimuth, and this change is related to fluid flow.
Many authors have shown that high angle fractures and cracks can cause seismic phenomenon of azimuthal anisotropy, on the contrary, by using the phenomenon of azimuthal anisotropy caused by fractures and cracks, we can predict the fracture development density and development orientation (Ruger, 1997). Pores and cracks filled with fluid would give rise to the "abnormal high attenuation", "low frequency shadow "phenomenon and so on, on the contrary, we use this response to predict the characterization of the reservoir filled with fluid or not.
In this paper, our theoretical foundation is based on" P-wave attenuation and dispersion which vary with azimuth". First of all, we carry out the work of frequency-dependent AVO inversion in different azimuthal gathers, then we can get different azimuthal dispersive properties; secondly, we use least square ellipse fitting algorithm to fit dispersive properties in different azimuths, thus we could obtain three ellipse attributes, including the major axis, minor axis and major axis direction; at last we can use these properties to describe the reservoir features.