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Collaborating Authors
Zhang, Lin
Outside the Box: Innovative Application of Diversion as a Replacement for Bridge Plug
Chang, Hong (5th Gas Plant of PetroChina Changqing Oilfield Company) | Yi, De Qiang (State Engineering Laboratory of Low-Permeability Oil & Gas Reservoir Exploration and Development ) | Lv, Yang (Oil & Gas Technology Research Institute of PetroChina Changqing Oilfield Company) | Zhao, Ming (5th Gas Plant of PetroChina Changqing Oilfield Company) | Cao, Peng Liang (5th Gas Plant of PetroChina Changqing Oilfield Company) | Zhang, Lin (5th Gas Plant of PetroChina Changqing Oilfield Company) | Hou, Rui (5th Gas Plant of PetroChina Changqing Oilfield Company) | Di, Yi Liang (5th Gas Plant of PetroChina Changqing Oilfield Company) | Chen, Jie (5th Gas Plant of PetroChina Changqing Oilfield Company) | Zhang, Lu (5th Gas Plant of PetroChina Changqing Oilfield Company) | Li, Hao Yan (5th Gas Plant of PetroChina Changqing Oilfield Company) | Fu, Yun Long (Schlumberger) | Liu, Yuan (Schlumberger) | Wang, Wei Kan (Schlumberger)
Abstract Effective stage-to-stage isolation is typically accomplished by setting a bridge plug in a properly cemented casing between stages. This isolation plays a vital role in a horizontal well multistage fracturing completion. Failure of isolation not only impacts the well productivity but also wastes fracturing materials. The challenges isolation failure poses for stimulation effectiveness include both detection and remediation. First, there has been historically no reliable and cost-effective solution to detect stage-to-stage isolation onsite. One may only start to realize this problem when inconsistent production is observed. Second, existing remedial actions are seldom satisfying in case of an isolation failure. Most commonly, a new plug is set to replace the failed one. However, because the perforation clusters of an unstimulated stage may create irregularities in well inside diameter (ID) (e.g., casing deformation or burr), there is a risk that the plug will be damaged or become stuck when it passes the perforation area. Also, when the plug passes a perforation cluster, the perforations start to take in the pump-down fluid, which can increase the difficulty of the pump-down job. A novel remedial action uses high-frequency pressure monitoring (HFPM) and diversion to solve both challenges. The stage isolation integrity is evaluated in quasi-real time by analyzing the water hammer after the pump shutdown. In the case of a plug failure, large-particle fracture diversion materials and techniques can establish temporary wellbore isolation through a quick and simple delivery process. To close the cycle, the effect of the diversion can be evaluated by HFPM, which can reveal the fluid entry point of the treatment fluid after diversion. The technique was applied to two cases in Ordos basin in which wellbore isolation failure interrupted the operation. The problem identification, development of the solution workflow, and observation from treatment analysis are discussed. In both cases, the stage-to-stage isolation was recovered, and the drilled sand body was successfully stimulated without involving costly and time-consuming well intervention. The stimulation operation of the entire well was successfully resumed in a timely manner.
- Asia > China > Shanxi Province (0.35)
- Asia > China > Shaanxi Province (0.35)
- Asia > China > Gansu Province (0.35)
- North America > United States > Texas (0.29)
- North America > United States > Texas > Haynesville Shale Formation (0.99)
- North America > United States > South Dakota > Williston Basin (0.99)
- North America > United States > North Dakota > Williston Basin (0.99)
- (11 more...)
Integrity Evaluation and Management in High Temperature High Pressure and High Production Rate Wells in Southwest China
Zhu, Dajiang (PetroChina Southwest Oil & Gasfield Company Engineering Technology Research Institute) | Fan, Yu (PetroChina Southwest Oil & Gasfield Company Engineering Technology Research Institute) | Zhang, Huali (PetroChina Southwest Oil & Gasfield Company Engineering Technology Research Institute) | Li, Yufei (PetroChina Southwest Oil & Gasfield Company Engineering Technology Research Institute) | Zhang, Lin (PetroChina Southwest Oil & Gasfield Company Engineering Technology Research Institute) | Wang, Chuanlei (PetroChina Southwest Oil & Gasfield Company Engineering Technology Research Institute) | Wang, Xiaolei (PetroChina Southwest Oil & Gasfield Company Engineering Technology Research Institute) | Chen, Hao (PetroChina Southwest Oil & Gasfield Company Engineering Technology Research Institute) | Lu, Linfeng (PetroChina Southwest Oil & Gasfield Company Engineering Technology Research Institute) | Duan, Yunqi (PetroChina Southwest Oil & Gasfield Company Engineering Technology Research Institute)
Abstract The Longwangmiao (referred to as LM) gas field in southwest China has characteristics of high temperature (144~156 °C), high pressure(75~76 MPa), and high production rate (70~100×10 m/d). Serious well integrity problems were encountered in the development process; 21% of 56 wells were subjected to sustained casing pressure (SCP)(≥20 MPa). Downhole leak detection logs indicated the main cause was tubing connection leakage at a depth range of 0~2400 m. Wellhead growth was present in 33 wells and 4 wells exhibited gas leakage through wellhead valves. Theoretical analysis and field tests were conducted to investigate and manage well integrity problems. A method to calculate the allowable pressure for different annuli was proposed based on string strength analysis, and downhole leak detection was conducted using ultrasonic leak detection method. A multi-string mechanical model to predict wellhead growth was established and the threshold values were calculated under different gas rates. According to the structure of wellhead, a method based on ultrasonic phased array to detect the work state of the wellhead was adopted, which measured the actual thickness of key valves to evaluate service life. For wells with SCP, the allowable pressure for different annuli was calculated and the pressure management charts were drawn and all wells were in steady production. Downhole leak detection showed that SCP in the A annulus (annulus between the tubing and production casing) was caused by connection leakage of tubing. In newly completed wells, a premium connection was adopted based on tests under cyclic structural and environmental thermal loads that the connections may encounter at various production phases, and the total ratio of SCP in newly completed wells decreased by 31.4%. Wellhead growth was predicted and compared with actual data, which showed an increase in average accuracy of 20~30% compared to the results from the WellCAT software. Sensitivity analysis revealed that the length of un-cemented casing and the production rate were the critical factors affecting the wellhead growth. The valve leakage of FF level material wellhead was caused due to corrosion after the removal of the coating, and no leakage was detected in the HH level material wellhead. Thickness survey showed that the average reduction was 0.085 mm~0.23 mm for HH wellhead, and 1.12 mm~2.24 mm for FF wellhead.
- Asia > China > Sichuan > Sichuan Basin > Moxi Field (0.99)
- North America > United States > Louisiana > China Field (0.97)
Distributed acoustic sensing (DAS) is an increasingly prevalent technology for seismic acquisition. DAS fibers posses many beneficial properties that make them an attractive candidate for microseismic monitoring, where DAS has experienced an important role. A key task in microseismic monitoring is the estimation of the source mechanism that generated the seismic data which provide the information about fracture type, in-situ stress, and whether fractures were generated during hydraulic fracturing or if existing fractures were reactivated. Information of this type is crucial for understanding the success of a hydraulic fracture treatment and for optimizing future treatments. Source mechanism information is encoded in the direct arrivals of the seismic energy emanating from propagating fractures. The source mechanism information is typically extracted from the direct arrivals through a process known as moment tensor inversion. However, because DAS is sensitive to a different portion of the wavefield than geophones or seismometers, moment tensor inversion does not directly transfer. Bearing this in mind, we design a deep learning workflow for extracting source mechanism information from DAS data. The workflow begins with a convolutional auto-encoder which compresses DAS-microseismic data to only those features relevant to moment tensor characterization. To extract the source mechanism information these features contain we further process them using two distinct methods; clustering and a generative adversarial network. Clustering is successful in grouping images with similar source mechanism allowing for inference about the source mechanism type of a given DAS-microseismic event based on the cluster to which it belongs. The generative adversarial network is trained to learn the relationship between the features extracted by the convolutional autoencoder and moment tensor labels. Fully trained, it is able to predict the moment tensor associated with a given DAS-microseismic event.
Wave propagation in rocks creates fluid pressure gradients and a local flow between stiff pores and compliant pores, Some alternative theories are based on the concept of which cause wave velocity dispersion. Dvorkin et al. (1995) double porosity (Pride and Berryman, 2003; Pride et al., derived a model, hereafter referred to as Dvorkin (1995) 2004; Ba et al., 2011; 2014; 2019; Zhang et al, 2019), model, to explain this phenomenon. Based on this theory, where the fluid flow is also due to pressure gradients we reformulate a new one, where the moduli of dry rock between soft and stiff pores, and the governing equations of skeleton are derived on the assumption that the boundary wave propagation are derived by incorporating two pore fluid pressure is constant. The new model has a better phases and one solid skeleton.
- Geology > Geological Subdiscipline > Geomechanics (0.47)
- Geology > Rock Type > Sedimentary Rock (0.32)
- Asia > China > Shanxi > Ordos Basin (0.99)
- Asia > China > Shaanxi > Ordos Basin (0.99)
- Asia > China > Inner Mongolia > Ordos Basin > Sulige Field > Ordos Formation (0.99)
- (3 more...)
ABSTRACT Acoustoelasticity describes the interaction of acoustic waves with nonlinear elastic deformations, particularly the change of wave velocity due to initial stresses or strains in a predeformed body. The theory extends the strain energy to cubic terms (third-order elasticity) and allows for finite strains to model deformations at high confining pressures. However, the theory considers equant (stiff) pores but neglects the effects of soft (compliant) pores, such as microfractures, cracks, and grain contacts. Our main contribution is to include these effects. Application of the novel poroacoustoelasticity theory to ultrasonic measurements on carbonate samples at varying confining pressures provides a better fit for the measured data of pressure dependence of wave velocity. We have quantified the contribution of the compliant pores to the nonlinear behavior of the wave velocity and determined the relation between the threshold pressure (beyond which the theories with and without compliant pores yield the same velocity) and porosity and permeability. The extension of poroacoustoelasticity theory by incorporating a dual-pore structure provides better description for stress dependence of wave velocity in fluid-saturated heterogeneous rocks, which can be applicable in further field studies regarding reservoir characterization and in situ stress estimation.
- Asia > China > Xinjiang Uyghur Autonomous Region > Tarim Basin (0.99)
- Asia > China > Sichuan > Sichuan Basin (0.99)
- North America > United States > Texas > Permian Basin > Yeso Formation (0.98)
- (23 more...)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (0.89)
Estimation of microfracture porosity in deep carbonate reservoirs based on 3D rock-physics templates
Pang, Mengqiang (Hohai University) | Ba, Jing (Hohai University) | Fu, Li-Yun (China University of Petroleum (East China)) | Carcione, José M. (Hohai University, Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS)) | Markus, Uti I. (Hohai University) | Zhang, Lin (Hohai University)
Abstract Carbonate reservoirs in the S area of the Tarim Basin (China) are ultradeep hydrocarbon resources, with low porosity, complex fracture systems, and dissolved pores. Microfracturing is a key factor of reservoir connectivity and storage space. We have performed measurements on limestone samples, under different confining pressures, and we used the self-consistent approximation model and the Biot-Rayleigh theory of double porosity to study the microfractures. We have computed the fluid properties (mainly oil) as a function of temperature and pressure. Using the dependence of seismic on the microfractures, a multiscale 3D rock-physics template (RPT) is built, based on the attenuation, P-wave impedance, and phase velocity ratio. We estimate the ultrasonic and seismic attenuation with the spectral-ratio method and the improved frequency-shift method, respectively. Then, calibration of the RPTs is performed at ultrasonic and seismic frequencies. We use the RPTs to estimate the total and microfracture porosities. The results indicate that the total porosity is low and the microfracture porosity is relatively high, which is consistent with the well log data and actual oil production reports. This work presents a method for identification of deep carbonate reservoirs by using the microfracture porosity estimated from the 3D RPT, which could be exploited in oil and gas exploration.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (0.68)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (0.50)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.46)
- Geophysics > Seismic Surveying > Surface Seismic Acquisition (0.68)
- Geophysics > Seismic Surveying > Seismic Processing (0.49)
- Asia > India > Rajasthan > Cambay Basin (0.99)
- Asia > India > Gujarat > Cambay Basin (0.99)
- Asia > China > Xinjiang Uyghur Autonomous Region > Tarim Basin > Tahe Field (0.99)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Carbonate reservoirs (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
Collapse columns in Permian and Carboniferous Formations of coal, Qinshui Basin, China
Liao, Zonghu (China University of Petroleum (Beijing)) | Zhang, Lin (China University of Petroleum (Beijing)) | Wen, Long (PetroChina Southwest Oil and Gasfield Company) | Zeng, Lianbo (China University of Petroleum (Beijing))
Abstract Seismic survey data collected for coal gas exploration show that there are many collapse columns distributed in the subsurface of Qinshui Basin, China. The interesting features of the collapse columns are observed by the seismic attributes, including the circular discontinuous patches on the horizon of the Shanxi Formation and multiple parallel discontinuities in vertical profiles of amplitudes. We speculate that the wide presence of these collapse columns are point constraints for the migration and accumulation of coal gas on a large scale. Geological feature: Collapse columns within coal reservoirs Seismic appearance: The coherence illuminates circular/oval discontinuities on the horizon of the Shanxi Formation; the vertical amplitude profiles show cylindrical/funnel-shaped discontinuities. Alternative interpretations: Fault damage zones; velocity pulldown from the overburden Features with similar appearance: Fault-karst in carbonate reservoir; reef pinnacles Formation: Permian Shanxi Formation and Carboniferous Taiyuan Formation Age: Late Permian Location: Qinshui Basin in Shanxi, north-central China Seismic data: Provided by PetroChina Huabei Oilfield Company Contributors: Zonghu Liao, Lin Zhang, and Lianbo Zeng Analysis tools: The seismic amplitude and attribute of coherence from the seismic survey (prestack time migrated)
- North America > United States > Louisiana (0.24)
- Asia > China > Hebei Province (0.24)
- North America > United States > Oklahoma (0.16)
- North America > United States > Texas > Anadarko Basin (0.99)
- North America > United States > Oklahoma > Anadarko Basin (0.99)
- North America > United States > Kansas > Anadarko Basin (0.99)
- Asia > China > Qinshui Basin (0.99)
Stochastic full-waveform inversion (SWI) of seismic data for FWI starting models
Chen, Jinsong (Chevron Energy Technology Company) | Albertin, Uwe K. (Chevron Energy Technology Company) | Nihei, Kurt (Chevron Energy Technology Company) | Kaplan, Sam (Chevron Energy Technology Company) | Hoversten, Michael (Chevron Energy Technology Company) | Zhang, Lin (Chevron Energy Technology Company) | Bevc, Dimitri (Chevron Energy Technology Company)
Current approaches for FWI based on a waveform misfit objective function have been demonstrated to be effective for high-fidelity imaging of acoustic and elastic properties, when starting from velocity models that are within the basin of attraction of the true velocity model. Such initial models need to include the long-wavelength structure sufficiently and accurately so that the synthetic and observed data misfit is less than half of a wavelength. If this condition is violated, gradient-based optimization methods can converge to a local rather than the desired global solution. Over the past several years, a clear focus of FWI research has been centered on finding new cycle-skip immune approaches for FWI by using a range of data, image and modeling domain objective functions. In this study, we develop a stochastic full waveform inversion (SWI) approach within a Bayesian framework to estimate the long wavelength starting model for FWI. We use Markov Chain Monte Carlo (MCMC) methods to draw many samples from model space described by sparse and smooth Gaussian radial basis functions (RBF). We demonstrate the effectiveness of SWI using a 2D marine synthetic salt model. Starting from a water bottom over half space model, SWI recovers a long wavelength starting model that allows standard least-squares FWI to correctly recover the true structure of the salt. Presentation Date: Tuesday, October 13, 2020 Session Start Time: 1:50 PM Presentation Time: 3:30 PM Location: Poster Station 3 Presentation Type: Poster
- Information Technology > Artificial Intelligence > Machine Learning > Statistical Learning (1.00)
- Information Technology > Artificial Intelligence > Representation & Reasoning > Uncertainty > Bayesian Inference (0.36)
- Information Technology > Artificial Intelligence > Machine Learning > Learning Graphical Models > Directed Networks > Bayesian Learning (0.36)
Estimation of crack porosity in deep carbonate reservoirs based on attenuation rock physics templates
Pang, Mengqiang (Hohai University) | Ba, Jing (Hohai University) | Fu, Li-Yun (China University of Petroleum (East China)) | Zhang, Lin (Hohai University) | Saenger, Erik H. (Hochschule Bochum and Fraunhofer IEG)
Carbonate reservoirs in the S area of the Tarim Basin (China), with low porosity, complex fracture systems and dissolved pores, are ultra-deep hydrocarbon resources. Especially, cracks play an important role in reservoir connectivity and storage space. To study the effect of cracks on reservoir, we have performed measurements on limestone samples under different confining pressures, and used the self-consistent approximation model and Biot-Rayleigh theory to simulate. Based on the dependence of seismic Q on the cracks, a multiscale attenuation template (RPT) is built, based on P-wave attenuation, impedance and phase velocity ratio. Then, calibration of the RPT is performed at ultrasonic and seismic frequencies to estimate the total and crack porosities of reservoirs. The results indicate that the distribution of the microcracks and pores were obvious different in the reservoirs. The total porosity is low (mostly < 5%), which is consistent with the geological structure and well-log data. The crack porosity is mainly between 0.06% and 0.12%, its behavior shows a good agreement with the actual oil production reports. Presentation Date: Tuesday, October 13, 2020 Session Start Time: 8:30 AM Presentation Time: 8:30 AM Location: 362D Presentation Type: Oral
- Geology > Geological Subdiscipline (0.88)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (0.51)
- Asia > India > Rajasthan > Cambay Basin (0.99)
- Asia > India > Gujarat > Cambay Basin (0.99)
- Asia > China > Xinjiang Uyghur Autonomous Region > Tarim Basin > Tahe Field (0.99)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management (1.00)
Density gradient for elastic FWI in Vp-Vs-density parameterization
Shen, Peng (Chevron Energy Technology Company) | Hua, Yong (Chevron Energy Technology Company) | Zhang, Lin (Chevron Energy Technology Company) | Albertin, Uwe (Chevron Energy Technology Company) | Sekar, Anusha (Chevron Energy Technology Company)
We study the relationship between the elastic FWI density gradient and the inverse scattering imaging condition. Due to the chain rule an elastic density gradient in different parameterization arrives at different forms. We show that in Vp-Vs-density parameterization the density gradient reduces to the inverse scattering imaging condition under the acoustic reduction. In a general elastic FWI scenario, under the same parameterization, the density gradient is typically free of long-wavelength backscattering artifacts. This gradient property suggests that the density, instead of being treated as an inversion artifact collector, can be utilized to construct meaningful and interpretable geological-geophysical objects. We argue that such a construction is closely linked to the least-squares reverse time migration (LSRTM). The difference, however, is that the FWI produces Heaviside-type step functions in the final result, whereas through pseudo-Born approximation, the result of LSRTM remains as the angle dependent band-limited Dirac delta function. We demonstrate the density inversion in elastic FWI using field data where the step functions are constructed. The field data we use has been preprocessed for imaging; despite this, however, we achieve a good match between synthetic data and observed data, including the AVO character. Presentation Date: Wednesday, October 14, 2020 Session Start Time: 8:30 AM Presentation Time: 8:30 AM Location: 361F Presentation Type: Oral