Integration of time-lapse seismic data into dynamic reservoir model is an efficient process in calibrating reservoir parameters update. The choice of the metric which will measure the misfit between observed data and simulated model has a considerable effect on the history matching process, and then on the optimal ensemble model acquired. History matching using 4D seismic and production data simultaneously is still a challenge due to the nature of the two different type of data (time-series and maps or volumes based).
Conventionally, the formulation used for the misfit is least square, which is widely used for production data matching. Distance measurement based objective functions designed for 4D image comparison have been explored in recent years and has been proven to be reliable. This study explores history matching process by introducing a merged objective function, between the production and the 4D seismic data. The proposed approach in this paper is to make comparable this two type of data (well and seismic) in a unique objective function, which will be optimised, avoiding by then the question of weights. An adaptive evolutionary optimisation algorithm has been used for the history matching loop. Local and global reservoir parameters are perturbed in this process, which include porosity, permeability, net-to-gross, and fault transmissibility.
This production and seismic history matching has been applied on a UKCS field, it shows that a acceptalbe production data matching is achieved while honouring saturation information obtained from 4D seismic surveys.
Jia, Wenlong (Southwest Petroleum University) | Yang, Fan (Southwest Petroleum University) | Mu, JunCheng (Kongsberg Gigital AS) | Cheng, Tingting (Southwest Petroleum University) | Li, Changjun (Southwest Petroleum University) | Zhang, Qi (Deepwater Engineering & Construction Center CNOOC China Ltd.-Shenzhen Branch)
Co-existence of gas, water and glycol is commonly in produced fluids of high-pressure gas wells due to formation water production and hydrate inhibitor injection. The interaction between the polar water and glycol molecules can affect the phase behavior and subsequent temperature change during gas flowing through chokes at wellheads. This paper presents an isenthalpic flash method based on the cubic-plus-association equation of state (CPA EOS) to calculate the temperature at the downstream of the choke. In comparison with the traditional isenthalpic flash algorithm, this new method accounts for the self- and cross-association between polar water and glycol molecules, yielding more accurate enthalpy calculation results for fluid containing water and glycol as well as choke temperatures. The proposed model is validated with field test data. Results demonstrate that the average absolute deviations between the measured and calculated temperatures at downstream of chokes based on the proposed method are less than 1.6°C even for vapor-liquid-aqueous three-phase mixtures at pressures up to 100 MPa. Results yield from the proposed method are more accurate than those calculated from the SRK EOS combining with the Peneloux volume shift method and the Huron-Vidal mixing rule.
Wang, Wendong (China University of Petroleum) | Zhang, Kaijie (China University of Petroleum) | Su, Yuliang (China University of Petroleum) | Tang, Meirong (PetroChina Oil & Gas Technology Research Institute of Changqing Oil field) | Zhang, Qi (China University of Geosciences) | Sheng, Guanglong (China University of Petroleum)
In the development of shale oil and gas reservoir, hydraulic fracture treatments may induce complex network configuration, which is very challenging to characterize. The existing fracture properties interpretation methods mostly rely on simplifying assumptions and are typically empirical in nature. The aim of this work is therefore to introduce an integrated framework involving fractal theory, inverse analysis of micro-seismic events (MSE), and rate-transient analysis to map the heterogeneity and distribution of fracture properties. In this work, a general framework is proposed to characterize both the geometry configuration and the owing properties of the complex fracture network (CFN). The CFN characterization framework is naturally divided into two stages: characterize the fracture geometry network by microseismic data and characterize the fracture dynamic properties by production data. In the fracture configuration characterization stage, a stochastic fractal fracture model based on an L-system fractal geometry is applied to describe the CFN geometry. Moreover, the genetic algorithm (GA) as a mixed integer programming (MIP) algorithm are applied to find the most probable fracture configuration based on the microseismic data. As to the owing properties characterization stage, we introduced embedded discrete fracture model (EDFM) for the computational concern and a Bayesian framework is used to quantify these fracture dynamical properties e.g., conductivity, porosity and pressure dependent multiplier by assimilating the production data. In addition, rate-transient analysis is also applied to calibrate the total fracture length and estimate effective stimulated-reservoir volume (ESRV). In order to validate this framework, a synthetic numerical case is developed. The result indicates that our integrated framework is able to characterize both CFN configuration and properties by assimilating microseismic and production data sequentially. The proposed workflow shows that the characterized CFN model would yield reasonable probability predictions in unconventional production rate.
Zhang, Qi (Shanghai Jiao Tong University, Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration (CISSE)) | Li, Wan-Ling (Shanghai Jiao Tong University, Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration (CISSE)) | Zhou, Xiang-Lian (Shanghai Jiao Tong University, Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration (CISSE)) | Wang, Jian-Hua (Shanghai Jiao Tong University)
The dynamic interaction between two parallel vibrating pipelines and local scour is investigated numerically in this research. A sediment scour model and the general moving objects (GMO) model are adopted to simulate the vortex-induced vibration (VIV) of pipeline and local scour. The numerical results indicated that the maximum scour depths under the vibrating pipelines are much larger than those under the fixed pipelines. Strong dynamic interaction between the two pipelines is observed. The shadowing effect of the upstream pipeline on the downstream pipeline is significant. The effects of G/D (the ratio of the distance between the two pipelines to the diameter of the pipelines) on the vortex shedding are obvious.
Submarine pipelines have been widely used in transporting the oil and gas from offshore to land. Submarine pipelines are subjected to long-term effects of waves and currents in ocean environment, which may lead the local scour under the pipelines. Once the scour hole under the pipeline is large enough, the free spanning pipeline may undergo vortex-induced vibration (VIV). Previous researchers mainly either focused on the wave or current induced local scour or the VIV of pipeline, respectively. Studies on the dynamic interaction between local scour and VIV of pipeline are scarce. Moreover, there are no related studies on the mechanisms of local scour below two parallel vibrating pipelines. Therefore, it is essential to understand the dynamic interactions between the two parallel vibrating pipelines, and the interactions between the two pipelines and the local scour.
A large number of previous researches have focused on the local scour below one or two fixed pipelines through experimental and numerical methods in the past few decades. The mechanisms of local scour, the scouring process, the time rate of scour developments, and the maximum scour depth under different experimental conditions were investigated in detail (Fredsoe et al., 1992; Mao, 1987; Sumer et al., 1988; Sumer and Fredsoe, 2001). Recently, researchers studied the local scour below pipeline through numerical method based on the fast development of computer technology. Several numerical models were carried out based on different theories such as the potential-flow theory, turbulent-flow theory and two-phase-flow theory, etc. The effects of fluid, pipeline and seabed characteristics, such as the current velocity, pipeline diameter, water depth, Froude number, etc., on the local scour below pipeline were examined ((Li and Cheng, 1999; Liang et al., 2005; Mirmohammadi and Ketabdari, 2011; Zhao and Cheng, 2010).
Wang, Liquan (Harbin Engineering University, Heilongjiang Institute of Technology) | Ma, Xinmeng (Harbin Engineering University, Heilongjiang Institute of Technology) | Wang, Gang (Harbin Engineering University, Heilongjiang Institute of Technology) | Chen, Xi (Harbin Engineering University, Heilongjiang Institute of Technology) | Jia, Peng (Harbin Engineering University, Heilongjiang Institute of Technology) | Zhang, Qi (Harbin Engineering University, Heilongjiang Institute of Technology)
The movement method of the crablike robot in amphibious environment is studied in order to make it possess autonomous motility in complex unstructured terrains, amphibious operation capability, strong environmental adaptability and stability of movement. The crablike robot prototype is developed based on the observation of the crab. The crablike robot’s ability to motility is analyzed for the purpose of establishing the kinematics and dynamics model of the leg. The parameters of the swimming paddle lift mode are calculated and the hydrodynamics of the corresponding mode is also analyzed. The ability of amphibious robot is verified through the performance of the crablike robot in pool and offshore environment.
Wei, Chenji (PetroChina) | Wang, Yuhe (Texas A&M University at Qatar) | Ding, Yutao (PetroChina) | Li, Yong (PetroChina) | Shi, Jing (PetroChina) | Liu, Shuangshuang (PetroChina) | Tian, Changbing (PetroChina) | Li, Baozhu (PetroChina) | Xiong, Lihui (PetroChina) | Zhang, Qi (PetroChina)
This paper presents an uncertainty assessment project using Artificial Neural Network (ANN) for a giant multi-layered sandstone reservoir in Middle East, which contains several uncertainties and associated risks. Uncertainty quantification in history matching, production forecasting and optimization approaches often requires hundreds of thousands of forward flow simulations to explore the uncertain parameter space, causing forbidden computational time requirement, especially for large-scale reservoir models. In order to bypass this limitation, one can use a proxy to replace the time-consuming flow simulator. In this work, an optimized ANN is used as the proxy and an uncertainty assessment workflow is implemented for the giant Cretaceous multi-layered sandstone reservoir using a global optimizer. Using the ANN based uncertainty assessment framework, the impacts of the main uncertain parameters on production forecasting are assessed for this multi-layered sandstone reservoir. Then, field development optimization is also performed to optimize wells injection and production rates to maximize the economic measures considering uncertainties.
Chen, Hanming (China University of Petroleum, Beijing) | Zhou, Hui (China University of Petroleum, Beijing) | Zhang, Qingchen (China University of Petroleum, Beijing) | Zhang, Qi (China University of Petroleum, Beijing)
Two staggered-grid finite-difference (SGFD) methods with fourth- and sixth-order accuracy in time have been developed recently based on two new SGFD stencils. The SGFD coefficients are determined by Taylor-series expansion (TE), which is accurate only nearby zero wavenumber. We adopt the new two SGFD stencils and optimize the SGFD coefficients by minimizing the errors between the wavenumber responses of the SGFD operators and the first-order k (wavenumber)-space operator in a least-squares (LS) sense. We solve the LS problems by performing weighted pseudo-inverse of nonsquare matrices to obtain the SGFD coefficients, and to yield two LS based SGFD methods. Dispersion analysis and numerical examples demonstrate that our LS based SGFD methods can preserve the original fourth- and sixth-order temporal accuracy and achieve higher spatial accuracy than the existing TE based time-space domain SGFD methods.
The staggered-grid finite-difference (SGFD) (Virieux, 1984) method has been widely used in seismic wave propagation modeling. Most of the SGFD applications adopt the traditional (2M, 2) scheme, which uses 2M-order Taylorseries expansion (TE) based FD operator to discretize spatial derivatives, and 2nd-order TE based FD operator to discretize temporal derivative. Although high-order spatial accuracy can be achieved by using a long stencil length, the temporal accuracy is only second-order. When a coarse time step is used, the traditional scheme suffers from obvious temporal dispersion during long time wave propagation.
Recently, Tan and Huang (2014a) propose two new SGFD methods with fourth-order and sixth-order accuracy in time respectively by incorporating a few of off-axial grid points into the standard SGFD stencil. The two methods are denoted as (2M, 4) and (2M, 6). The FD coefficients are determined in the time-space domain using TE approach. Althouth high-order temporal accuracy has been achieved, the TE based (2M, 4) and (2M, 6) methods still suffer from obvious spatial disperion when a large grid size or a short stencil length is adopted. Tan and Huang (2014b) continue to improve the spatial accuracy by using a nonlinear optimization to seek the optimal FD coefficients. However, the optimization requires repeated iterations, and the procedure may be time-consuming.
Wei, Chenji (Research Institute of Petroleum Exploration & Development, PetroChina) | Li, Yong (Research Institute of Petroleum Exploration & Development, PetroChina) | Li, Baozhu (Research Institute of Petroleum Exploration & Development, PetroChina) | Wang, Yinxi (China National Oil and gas Exploration & development, PetroChina) | cai, Kaiping (Subsurface Department, Rumaila Operating Organization(ROO)) | Zhang, Qi (Research Institute of Petroleum Exploration & Development, PetroChina) | Zhou, Jiasheng (China National Oil and gas Exploration & development, PetroChina)
Understanding the heterogeneity is critical for a successful water injection in a carbonate reservoir. Thief zone is one of the most obvious forms of heterogeneity, which indicates the thin layer with higher permeability compared with average reservoir permeability. The existence of thief zone results in earlier water breakthrough and faster water cut increase, which lead to smaller sweep efficiency and lower recovery factor. Therefore, determining the thief zone distribution and proposing corresponding development plan are very important.
This paper focuses on a super-giant carbonate reservoir, which is a Cretaceous carbonate reservoir in Middle East, with an OOIP of more than 20 billion barrels. Thief zones are widely distributed in this carbonate according to the production logging test (PLT). In this paper, we combined geological understanding and dynamic behavior to summarize different types of thief zone distribution, which means the different locations and scales of thief zone and barriers. Then, geological model is built, and reservoir simulation is conducted on the models corresponding to different types to optimize the development strategy.
The optimized parameters include well pattern and perforation strategy. Then, development strategies are proposed for different types of thief zone distribution. Results indicate that location of thief zone hasobvious impact on the production. In order to mitigate the impact of thief zone, line drive pattern is preferred when the permeability ratio is high. Most importantly, different types of thief zone distribution require specified perforation strategy, and optimizeddevelopment strategies could save more than 25% of injected water by mitigating the futile cycle of injected water.
This paper offers a case study that summarizes different types of thief zone distribution and optimizes the development strategy for different scenarios. It also provides a methodology and reference case for engineers and geologists to develop other similar fields.
Wang, Hui (National Marine Data & Information Service) | Liu, Kexiu (National Marine Data & Information Service) | Fan, Wenjing (National Marine Data & Information Service) | Zhang, Qi (National Marine Data & Information Service) | Zhang, Zengjian (National Marine Data & Information Service) | Wang, Guosong (National Marine Data & Information Service)
Based on the data of coastal tide level in China and of satellite altimeter and sea surface temperature in offshore areas of the Chinese coast and equatorial Pacific, the relationship between the sea level variation in China and ENSO are investigated. The research results show that, sea level change shows a fluctuent ascending trend along the coastal region of China, and the average rise rate is 2.9mm/yr in recent 30 years which is higher than the global average. The coastal sea level of China presents prominent inter-annual variation and inter-decadal variation besides the seasonal variation. The significant periods are 2-3a, 4-7a, 9a, 11a and 19a, and the oscillation of 4-7a is the most prominent in spring, which amplitude is close to 2cm. In El Niño events, the coastal sea level of China was lower than those in normal years, and it was obviously affected by ENSO. Annual and semiannual amplitudes of sea level significantly decreased in El Niñoevents. The minimum values of annual amplitudes all appeared in El Niño years, but in different regions they happened in different years. In addition, the solar annual constituent Sa amplitude of Chinese coast is related with the strength of El Niño events. Response area and magnitude are bigger in strong events, and are smaller in weak events. There is a significant negative correlation between monthly mean sea level in offshore areas of the Chinese coast and SST in the central and eastern equatorial Pacific, and the correlation coefficient is -0.42. It also shows that sea level in offshore areas of the Chinese coast is negatively correlated with Nino4 and Nino3.4 indices.
Most of the numerical analyses currently used for evaluation of the stability of underground excavations are based on a linear Mohr–Coulomb strength criterion. However, experimental data and experience of the field engineering showed that the strength of nearly all types of rock mass followed with the non-linear Hoek–Brown strength criterion. The Hoek–Brown strength criterion for rock mass is widely accepted and applied in a large number of engineering in the world. This paper briefly introduces Mohr–Coulomb strength criterion and Hoek–Brown strength criterion as well as the parameters considered in the two strength criterion. The effects of the geological condition parameters considered in Hoek–Brown strength criterion, disturbed factor D, and intact rock constant mi on the rock mass strength are studied. The geological conditions of the rock mass are indicated by volumetric discontinuity frequency λv, infilling rating Rf, roughness rating Rr and weathering rating Rw of the discontinuity and represented by the Geological Strength Index (GSI). To embody the advantage of Hoek–Brown strength criterion, a deeply buried tunnel is involved in numerical analysis with GeoFBA3DV2.0.The numerical result reflects the superiority that Hoek–Brown strength criterion can consider the instant and sectional geological condition with the link of GSI. Tunnel design with Hoek–Brown strength criterion can use the accurate surrounding rock parameters following the tunnel excavation and avoid the waste of uniformly distributed support structure using global design concept.
Analysis of a variety of problems in rock mechanics and rock engineering requires determination of the rock mass strength. Over the past decades, several different strength criteria have been developed for rock and rock mass. Most of the numerical analyses currently used for the evaluation of the stability of underground excavations or rock slope are based on a linear Mohr–Coulomb strength criterion (Hoek 1990).The Mohr–Coulomb strength criterion is widely used because of its simple expression of liner equations in principal stress space and easy determination of its parameters.