Li, Wenbin (CNOOC China Limited, Tianjin Branch) | Liu, Lei (CNOOC China Limited, Tianjin Branch) | Wang, Jianli (CNOOC China Limited, Tianjin Branch) | Liu, Xuetong (CNOOC China Limited, Tianjin Branch)
As we all know, accuracy of the migration velocity determines the quality of imaging results to a large extent. However, traditional migration velocity analysis methods always fail in gas cloud area due to the complex wave field and poor quality of the seismic data. Aiming at this problem, we present a high precision velocity model building technology for gas cloud areas to improve seismic imaging quality in these areas. Diving wave always appears as first arrival and its ray density satisfies inversion demand well, which makes it easy to pick up shallow information and sensitive to velocity anomalies. Thus, we build velocity model for gas cloud areas based on both diving and reflected wave. Firstly, diving wave tomography inversion is carried out to establish a high precision velocity model of shallow layers. Then we perform reflection tomography inversion to get velocity model of deeper layers with shallow layers’ velocity model above as initial input. Finally, we build the accurate velocity model of gas cloud areas successfully.
The results of real data processing in P oilfield show that the velocity model built by our method has a better precision in gas cloud areas and matches the VSP velocity better in both gas cloud areas and normal areas. In contrast to the images based on conventional reflection wave velocity model, the imaging result based on our velocity model is obviously improved. Our method is widely applicable to the study of gas cloud areas and will help the understanding and interpretation of seismic data in gas cloud areas greatly.
Chen, Hongquan (Texas A&M University) | Yang, Changdong (Texas A&M University) | Datta-Gupta, Akhil (Texas A&M University) | Zhang, Jianye (Institution of Exploration and Development of Tarim Oilfield Company-Petro China) | Chen, Liqun (Institution of Exploration and Development of Tarim Oilfield Company-Petro China) | Liu, Lei (Institution of Exploration and Development of Tarim Oilfield Company-Petro China) | Chen, Baoxin (Institution of Exploration and Development of Tarim Oilfield Company-Petro China) | Cui, Xiaofei (Optimization Petroleum Technology, Inc.) | Shi, Fashun (Optimization Petroleum Technology, Inc.) | Bahar, Asnul (Kelkar and Associates, Inc.)
History matching of million-cell reservoir models still remains an outstanding challenge for the industry. This paper presents a hierarchical multi-scale approach to history matching high resolution dual porosity reservoir models using a combination of evolutionary algorithm and streamline method. The efficacy of the approach is demonstrated through application to a high pressure high temperature (HPHT) fractured gas reservoir in the Tarim basin, China with wells located at an average depth of 7500 meters.
Our proposed multi-scale history matching approach consists of two-stages: global and local. For the global stage, we calibrate coarse-scale static and dynamic parameters using an evolutionary algorithm. The global calibration uses coarse-scale simulations and applies regional multipliers to match RFT data, well bottom hole pressures, and field average pressure. For the local stage, we calibrate fracture permeability using streamline based sensitivities to further match well bottom-hole pressures. The streamlines are derived from the fracture cell fluxes and the sensitivities are analytically computed for highly compressible flow. The sensitivities are validated by comparison with the pertubation method.
The proposed hierarchical multiscale history matching workflow is applied to a faulted and highly fractured deep gas reservoir in the Tarim basin, China. The excessive well cost arising from the large well depth (7500 meters) and high pressure (18000 psi) necessitates optimal field development with limited number of wells. The fracture properties of dual porosity model are upscaled from a highly dense discrete fracture network model generated based on well data and seismic attributes. The history matching includes RFT data, static pressure data and flowing bottom-hole pressure data in producing wells. Field average pressure and RFT (static pressure) data were well matched during the global stage using coarse scale models while flowing bottom-hole pressure is further matched during the local stage calibration using fine scale models. Streamline method has been applied previously mainly to incompressible or slightly compressible flow. However in this application, the results show that the modified streamline-based sensitivity can also significantly reduce data misfit for highly compressible flow. The history matched models are used to visualize well drainage volumes using streamlines. The well drainage volumes in conjunction with static reservoir properties are used to define a ‘depletion capacity map’ which is then used for optimal infill well placement.
The novelty of our approach lies in the application of streamlines derived from dual porosity finite-difference simulation to facilitate history matching and well placement optimization in a tight gas reservoir. The newly developed streamline-based analytical sensitivities are suitable for highly compressible flow. To our knowledge, this is the first time streamlines have been used to facilitate history matching and optimal well placement for gas reservoirs.
Liu, Lei (Shanghai Jiao Tong University, Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration) | Lu, Haining (Shanghai Jiao Tong University, Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration) | Yang, Jianmin (Shanghai Jiao Tong University, Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration) | Peng, Tao (Shanghai Jiao Tong University, Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration) | Tian, Xinliang (Shanghai Jiao Tong University, Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration)
Numerical study of the free-fall of a single sphere at different Reynolds numbers has been conducted with Computational Fluid Dynamics(CFD) method based on the engineering concerns of the dynamics of ore particles in vertical pipes in deep sea mining. A combination of Detached Eddy Simulation (DES) and the six-degree-of-freedom (6-DOF) motion solver was adopted. The sphere motion, the hydrodynamic forces on the sphere and the characteristics of the surrounding flow field were analyzed in detail. Different falling trajectories of the sphere were observed. The surrounding flow field gradually lost the symmetry with the increase of Reynolds number. The results of this article would provide a basic reference for the further investigation on motion of the multiple ore particles.
As the increasing demand of the natural sources in the world, deep sea deposits are considered as the most valuable alternative sources. Deep sea mining applications has been proposed since 1960s (Mero, 1965; Willums and Bradley, 1974; Chung, 1999; Chung, 2005; Chung, 2009). One of the most important issues in deep sea mining is the ore transportation from seafloor. Typically, ore particles can be transported vertically to the support vessels in the upward flow of water in a riser. Significant efforts have been dedicated to the vertical hydraulic transport system in deep sea mining (Engelmann, 1978; Bournaski et al., 2001; Xia et al., 2004; Chung et al., 2007; van Wijk, 2016).
Engelmann (1978) conducted experimental investigation on the hydrodynamic behaviors of ore particles in a vertical tube, and established the empirical equations for designing the hydraulic transport system in deep sea mining. Chung et al. (1998), Chung et al. (2001) and Chung et al. (2007) had a thorough investigation on the vertically upward transport in deep sea mining, including the transportation of spherical bead and non-spherical particles, the effects of particle shape and size, different particle behaviors over a wide range of Reynolds number in both Newtonian fluid and non-Newtonian fluids. Yoon et al. (1999), Yoon et al. (2001) and Yoon et al. (2008) studied the flow characteristics of the solid-liquid two-phase mixture in both vertical tubes and flexible hoses. Bournaski et al. (2001) and Xia et al. (2004) studied the hydraulic gradient caused by the fluid, the coarse particles and the collisions in the vertical pipes. Parenteau (2010) carried out numerical simulations to investigate the transient behaviors and pressure predictions for the risers by using Computational Fluid Dynamics (CFD) methods. Talmon and Rhee (2011) designed a close-loop system in the laboratory to conduct experiments on ore transport over large vertical distances. Sobota et al. (2013) experimentally investigated the velocities of ore particles and carrier liquid to determine the slip velocities for the artificial nodules in the vertical pipe. Vlasak et al. (2014) studied the influence of pipe inclination, solid concentration and mixture velocity on the characteristics of particle-water mixtures by using a pipe loop system. van Wijk (2016) carried out a study into flow assurance of the hydraulic transport system in deep sea mining and proposed a onedimensional flow model to investigate the mechanisms leading to the riser blockage.
Zhang, Qiu (China University of Petroleum–East China) | Zhang, Junhua (China University of Petroleum–East China) | Zhang, Xiaohui (China University of Petroleum–East China) | Wen, Hu (China University of Petroleum–East China) | Liu, Lei (Sinopec Shengli Oilfield)
As for thin reservoir, how to determine the spatial distribution regularity of thin reservoir and its property has become an urgent problem. Spectral inversion technique makes use of sparse reflection coefficient to calculate parameters to estimate rock physical property. Comparing with the conventional inversion theory, spectral inversion can provide different results. This paper uses the model to prove that spectral inversion has higher resolution when the reflection coefficient is sparse. That means spectral inversion has higher resolution when give more accurate initial reflection sequence. Based on predecessor's research, we know that synchrosqueezing wavelet transform (SWT) has higher time-frequency resolution compared with other time-frequency analysis tool. In this paper, we propose a method to pick up the initial reflection sequence for spectral inversion by SWT and make a good effect. After that, we process the real seismic data. First, get the initial reflection sequence by SWT. Second, use spectral inversion based on simulated annealing to calculate the final result. Comparing the original seismic data with the data processed by spectral inversion, we can find that spectral inversion can improve the resolution of seismic data obviously and broaden seismic frequency band, which can help to describe tiny geological targets and their internal features clearly.
Presentation Date: Thursday, October 20, 2016
Start Time: 11:25:00 AM
Presentation Type: ORAL
Limin, Zhao (Chengdu University of Technology, Sichuan, China, RIPED, Petrochina) | Duan, Tianxiang (RIPED, Petrochina) | Han, Haiying (RIPED, Petrochina) | Xu, Jiacheng (RIPED, Petrochina) | Guo, Rui (RIPED, Petrochina) | Zhu, Xiang (Chengdu University of Technology) | Liu, Lei (Chengdu University of Technology)
Accurate geological characterization for complex carbonate reservoirs plays an important role in guiding the optimal oilfield development. Mishrif Formation of H Oilfield in south of Iraq is the most important target among several Cretaceous oil-bearing carbonate formations due to the high OOIP proportion. It is composed mainly of bioclastic limestone with multiple pore types. It is massive reservoir with medium porosity and low permeability. The great variation of vertical and lateral reservoir quality leads to poor relationship between porosity and permeability which brings great challenge in reservoir characterization and favorable area identification. This paper presents the comprehensive reservoir evaluation and characterization in combination of all data available. The sedimentology and stratigraphy are reviewed in terms of depositional environment and lateral stratigraphic correlation. The variability inherent to the depositional mode and digenesis leads to complex reservoir geometry and pore types. Rock typing is examined based on core measurements and well logs to get the improved correlation coefficient between porosity and permeability. Neutral network method is used to propagate the rock types to un-cored wells to get the accurate permeability estimation. Facies model and rock type model are built constrained by the seismic inversion reservoir prediction results which provide crucial information on carbonate proportions distribution, especially in areas with low well control. Permeability model is generated constrained by rock type and porosity which can indicate the reservoir flow capacity. Based on the integrated reservoir model, horizontal wells and multilateral wells for Mishrif Formation are proposed and optimized in the good reservoir quality area. The high individual well production rate verified that the well placements upon fine reservoir modeling are successful.
Multiples predicted by surface-ralated multiple elimination (SRME) and many other methods have to convolve with a matching filter for the purpose of being correctly subtracted from original data. The blind separation of convolved mixtures (BSCM) method uses a L1 estimator to estimate the matching filter. The matching filter calculated by BSCM is proved performing better than least square matching filter. However, the computational complexity of BSCM is much larger than least square methods. This shortcoming limited its use when the size of the matching filter increases or the matching filter is designed a 3D filter. In this abstract, we proposed an accelerated method which is called FBSCM. This algorithm uses the iterative shrinkage-threshold strategy to decrease the complexity of the iteration procedure in BSCM. The support region of the matching filter is detected to decrease the dimension of the L1 estimator. The combination of these two strategies accelerated the BSCM method about 10-20 times of the computing time. The examples are given to show that the performance of FBSCM compared with least square matching filter and BSCM.
Surface-related multiple elimination (SRME) (Berkhout and Verschuur, 1997) has been considered as an effective method for multiples suppression. The distortion and the time and spatial mismatch in the predicted multiples require an adaptive subtraction of multiples from original data after the SRME procedure. A linear matching filter calculated from Least Square (LS) estimation is firstly considered for this purpose (Berkhout and Verschuur, 1997). However, the LS matching filter has a relatively poor performance when the multiple events and the primary events have overlaps, which may cause residuals of multiples or damage to primaries. Improvements on the estimation of the matching filter have been proposed to better subtract the multiples. Among them, Li et al. (2012), Li and Lu (2013) proposed a multiple subtraction method based on the blind separation of convolved mixtures (BSCM). This method considers the non-Gaussianity of the primaries and uses L1 estimator to calculate the 2D or 3D matching filter.
L1 estimator is widely used in robust estimation. However, the calculation of a L1 estimator is traditionally by iterative reweighted least square method (IRLS) (Holland and Welsch, 1977) which is much slower than the calculation of a least square (LS) estimator. When used for BSCM, the increase of the computational complexity is mainly caused by two reasons:
Liu, Lei (Shanghai Jiao Tong University) | Yuan, Hongtao (Shanghai Waigaoqiao Shipbuilding Co., Ltd.) | Yang, Jianmin (Shanghai Jiao Tong University) | Tian, Xinliang (Shanghai Jiao Tong University) | Li, Chunhui (Shanghai Waigaoqiao Shipbuilding Co., Ltd.) | Lu, Haining (Shanghai Jiao Tong University)
Offshore platforms under construction are normally moored on the dock during the outfitting stage. The safety of the platforms must be guaranteed during the whole stage of outfitting which may last for several months. This paper presents a wave basin model test study of a jackup moored on the dock in Shanghai Waigaoqiao shipyard in China. In the model test, the jackup and the sea states were scaled based on the Froude similarity law. The dynami c responses of the system, including the six degrees of freedom (6DOF) moti ons of the jackup and the barge, tensions on the mooring lines and the collision forces on the fenders, were measured in various sea states. Meanwhile, the current-and-wind-only sea states were simula ted and the dynamic responses were measured for comparison with those in the wave conditions. The mooring line tensions were found to excee d the strength of the lines in offshore wind conditions. And this phenomenon may be attributed to the decrease of the jackup's yaw m otion stiffness. In addition, several suggestions are proposed for optimizing the mooring system performance.
Predictive deconvolution is an old but very widely used multiple suppression method. The method makes the assumption that the primaries and the multiples are orthogonal, which is often dissatisfied. Some researches show that maximize the non-Gaussianity of the deconvolution results is a better way than the traditional method when the primaries and the multiples are not orthogonal. Based on this basic idea, we find that maximize the non-Gaussianity of the estimated primaries and the predictive filter at the same time can further improve the deconvolution result.
Predictive deconvolution is often applied after divide the seismic trace into segments to overcome some time-varying factors in real field data. The segmented method does not always work well since short segments may cause overfitting effect while long segments may fail to remove multiples. We propose an algorithm that firstly calculate a global predictive filter and then adjust the scale of the filters in each segments based on non-Gaussianity maximization. The proposed algorithm outperforms the segmented method in both synthetic data tests and real field data test.
Zhang, Lei (Research Institute of Petroleum Exploration and Development, PetroChina) | Zhang, Guangya (Research Institute of Petroleum Exploration and Development, PetroChina) | Liu, Lei (Research Institute of Petroleum Exploration and Development, PetroChina) | Chen, Xi (Research Institute of Petroleum Exploration and Development, PetroChina)
Chaco basin has favorable geological conditions for tight oil and gas, including high quality source rocks and reservoirs. Undiscovered oil and gas reserves are large.
The Chaco Basin is a foreland basin with an approximate area of 284,000 sq km, lies on the eastern side of the Andes, in Bolivia, northern Paraguay, and northwestern Argentina. Three structural domains are recognized in the basin: (a) a thin-skinned, northeast to southeast-vergent fold-thrust belt, which has deformed the western fringe of the basin along the edge of the Eastern Cordillera; (b) a foothill belt where this deformation is attenuated or incipient; and (c) the Andean foreland. Thus, on the basis of these features, the Chaco Basin is divided into four sub-provinces: the Chaco Sub-Andean Zone, the Chaco Foothill Belt, the Chaco Sub-basin, and the Izozog High. The Izozog High constitutes the southeastern, undeformed part of the basin. The Western part of basin was intensively affected by tectonic movements, anticlines are developed. The eastern part of basin mainly develop gentle structures, Cenozoic strata are exposed on surface. Tectonics are usually controlled by basement faults. Thickness of sedimentary rocks are over 6000 meters, strata include Devonian, Carboniferous, Permian, Triassic, Cretaceous and Cenozoic. Discovered oil and gas are mainly concentrated in the Chaco Sub-Andean Zone and the Chaco Foothill Belt, in the western part of the Basin. The approximate remaining recoverable (proven and probable) reserves of the basin are 1,100 MMbo and 62,300 Bscfg, which categorize the basin as extremely prospective. Total reserve distribution is as follows: 80% in Bolivia, 20% in Argentina and less than 1% in Paraguay.
Qiu, Wei (Ocean Engineering Research Centre, Memorial University of Newfoundland) | Peng, Heather (Ocean Engineering Research Centre, Memorial University of Newfoundland) | Liu, Lei (Ocean Engineering Research Centre, Memorial University of Newfoundland) | Mintu, Shafiul (Ocean Engineering Research Centre, Memorial University of Newfoundland) | Hsiao, Chao-Tsung (Dynaflow Inc.)