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Collaborating Authors
CNOOC Ltd.
Multi-scale joint characterization of braided river dominant facies: A case study of C1 oilfield in the Bohai Bay basin
Wang, Feiteng (CNOOC Ltd.) | Zhang, Zhang (CNOOC Ltd.) | Song, Hongliang (CNOOC Ltd.) | Guo, Jingmin (CNOOC Ltd.) | Zhang, Xiaolong (CNOOC Ltd.)
The C1 oilfield in the Bohai Bay Basin is a typical braided river reservoir, and single well production varies greatly in different regions. In order to solve above problems, this research used pore structure, particle size analysis, core, log facies and multiple seismic attributes fusion to realize refined description and sedimentary microfacies division. Firstly, pore throat characteristics and particle size distribution of different regions were studied based on microscale observation and measurement. Then, superior and inferior channel bars, dominant facies were determined by comprehensive information of microscale analysis, log facies and multiple seismic attributes fusion. The results showed that superior channel bar has a coarse grain, low argillaceous content, inclined bedding and “smooth box” log facies, while the median sizes are mainly distributed in 70 to 180 um, indicating the channel has a strong hydrodynamic force, which leads to the single well production is relative high. Inferior channel bar has a fine grain, high argillaceous content, cross bedding and “jagged box” log facies, while the median sizes are mainly distributed in 20 to 40 um, indicating the channel has a weak hydrodynamic force, which leads to the single well production is relative low. Moreover, based on seismic attribute analysis, RMS and sweetness attributes were fused to distinguish the plane difference, and a significant banded deposition was showed in the western research area. Combined the plane feature with microscale analysis and log facies characteristics, dominant facies were determined.
- Geology > Geological Subdiscipline (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (0.71)
- Asia > China > East China Sea > Bohai Basin > Jiyang Basin > Guantao Formation (0.99)
- Asia > China > Bohai Basin (0.99)
Advantages and applications of seismic data interpretation in depth domain
Li, Shaoxuan (CNOOC Ltd.) | Peng, Gang (CNOOC Ltd.) | Wang, Jianli (CNOOC Ltd.) | Tian, Tao (CNOOC Ltd.)
Pre-stack depth migration (PSDM) has significant advantages in imaging complex structural areas. However, it cannot be avoided that the relative depth relationship between wells on the seismic section in time-domain during the seismic interpretation stage contradicts the actual drilling results. This paper compares the data in time-domain and in depth-domain after PSDM, and comprehensively analyzes the advantages of seismic data interpretation in depth-domain. The numerical model shows that the PSDM data in time-domain has the problems of construction traps and interpretation error accumulation. In addition, interpretation in depth-domain seismic data has the advantages of simple process, reduced interpretation multiple solutions, and high interpretation accuracy. Interpretation work based on depth-domain seismic data in R oilfield of Bohai Bay has achieved remarkable results. The actual interpretation results show that it has higher accuracy than conventional methods, especially in complex structural areas. Note: This paper was accepted into the Technical Program but was not presented at the 2020 SEG Annual Meeting.
- Asia > China (0.72)
- Africa > Middle East > Libya > Wadi al Hayaa District (0.26)
- Geophysics > Seismic Surveying > Seismic Interpretation (1.00)
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (0.50)
- Asia > China > East China Sea > Bohai Basin > Jiyang Basin > Guantao Formation (0.99)
- Africa > Middle East > Libya > Wadi al Hayat District > Murzuq Basin > Block NC 186 > I&R Fields > R Field > Mamouniyat Formation (0.99)
- Africa > Middle East > Libya > Wadi al Hayat District > Murzuq Basin > Block NC 115 > I&R Fields > R Field > Mamouniyat Formation (0.99)
Research and application of mixed phase deconvolution technique in reservoir prediction of Guantao Formation in Bohai
Wang, Yichuan (CNOOC Ltd.) | Zhao, Ye (CNOOC Ltd.) | Xie, Xiang (CNOOC Ltd.)
The reservoirs of the Guantao Formation in the Penglai area of the Bohai Oilfield are thin and interbedded. The seismic response energy is weak, the continuity is poor, the resolution is low, and even weak white reflections appear, which brings great difficulties to reservoir identification. Aiming at this problem, this paper takes the Penglai block as an example to analyze the seismic response characteristics and the genetic mechanism of the Guantao Formation from the statistical analysis of the well seismic data and the forward simulation results. Aiming at the seismic response of Guantao Formation, based on diffusion filtering, a hybrid phase wavelet extraction method based on time-frequency spectrum simulation to extract amplitude spectrum and extracting phase spectrum in complex spectrum domain is proposed for deconvolution processing. Therefore, the seismic profile noise is suppressed, the continuity of the seismic axis is enhanced, the seismic response resolution of the target interval is improved, and the seismic data quality is improved. The ideal effect is obtained in the reservoir prediction of the Guantao Formation in the Penglai area of the Bohai Oilfield. Note: This paper was accepted into the Technical Program but was not presented at the 2020 SEG Annual Meeting.
- Asia > China (0.47)
- North America > United States > Texas > Dawson County (0.26)
- Information Technology > Data Science > Data Quality (0.69)
- Information Technology > Modeling & Simulation (0.48)
Migration artifacts and structural interpretation beneath gas clouds
Li, Shaoxuan (CNOOC Ltd.) | Peng, Gang (CNOOC Ltd.) | Tang, Hebing (CNOOC Ltd.) | Sun, Junting (CNOOC Ltd.)
The shallow gas cloud has a strong absorption and attenuation effect on P wave, and changes the travel time of P wave. It leads to the degradation of seismic data quality, which challenges the seismic data interpretation. From the perspective of kinematics, the imaging characteristics of the structures beneath the gas cloud areas on different migration sections are compared and analyzed through numerical models. It is recommended that seismic interpretation work can be carried out directly on the PSDM data in depth-domain to avoid the imaging problems of PSTM data and the structural trap problems of PSDM data in time-domain. Here we present a case study in which we applied depth-domain PSDM data interpretation in the K oilfield of Bohai Bay. The practical application results show that interpretation based on PSDM data in depth-domain beneath gas cloud areas can reduce the interpretation multiplicity, increase the depth prediction accuracy, and improve the drilling success rate of the development wells. Note: This paper was accepted into the Technical Program but was not presented at the 2020 SEG Annual Meeting.
- Geophysics > Seismic Surveying > Seismic Interpretation (0.71)
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (0.69)
The polarity discrimination method of seismic data based on correlation of seismic attributes and its application in Bohai A oilfield
Guo, Shuai (CNOOC Ltd.) | Wang, Bo (CNOOC Ltd.) | Xia, Tongxing (CNOOC Ltd.) | Wei, Hong (CNOOC Ltd.)
Well-seismic calibration is basis of structural interpretation and reservoir prediction in geophysical research, whose results directly determine the accuracy of structural interpretation and reservoir prediction. The determination of the polarity of seismic data is the most basic work of well-seismic calibration. The correct identification of the polarity of seismic data can not only more accurately calibrate the interpretation horizon and describe the reservoir, but also has important significance for the description of the interlayer within the reservoir. At present, the methods to judge the polarity of seismic data mainly include wavelet extraction, synthetic seismogram, single / double track judgment method, etc. The premise of these methods is that the residual wavelet on the reservoir profile is assumed to be zero phase, which is not the real case, so it is easy to misjudge. Therefore, in view of the conventional polarity judgment method, two improvements are put forward. By using the two-color display to highlight the contrast of strong amplitude, using the marker layer with clear impedance relationship in shallow layer to calibrate and judge, and according to the situation of "one positive and one negative" / "one negative and one positive" in the top-bottom interface and the similar energy intensity, by extracting a set of stable and independent lithology stratum top and bottom seismic attributes,based on the correlation analysis of seismic attributes, a method for polarity judgment and verification of seismic data is proposed, which has been successfully applied in Bohai A oilfield. Note: This paper was accepted into the Technical Program but was not presented at the 2020 SEG Annual Meeting.
- Asia > China (0.48)
- North America > United States > Texas > Dawson County (0.45)
- Geophysics > Seismic Surveying > Seismic Processing (1.00)
- Geophysics > Seismic Surveying > Seismic Interpretation (1.00)
Hydrates on the subsea wellhead in deepwater wells: Study on the growth mechanisms, impacts on drilling safety, and possible solutions
Zhang, Bailing (China University of Petroleum (Beijing)) | Yang, Jin (China University of Petroleum (Beijing)) | Takbiri-Borujeni, Ali (West Virginia University) | Sun, Ting (China University of Petroleum (Beijing)) | Edrisi, Ali Reza (Nicholls State University) | Takbiriboroujeni, Hojatollah (Isfahan University) | Wu, Xudong (CNOOC Limited Drilling and Completion Office) | Liu, Hexing (CNOOC Ltd.) | Bo, Zhou (CNPC Drilling Research Institute)
Abstract Hydrate formation poses a risk to deepwater drilling operations. Most current studies on the hydrate formation and its impact on deepwater drilling operations have focused on the risk associated with hydrates inside the wellbore. Few researchers have studied the risk of hydrate formation outside the wellbore, and the risks to deepwater drilling are still unclear. In the South China Sea, there have been several events of hydrate growth on the outer surfaces of the subsea wellhead. The mechanisms of hydrate growth on the outer surface of the subsea wellhead are analyzed, and the gas source is predicted by analyzing the logging data of the adjacent wells. A model for the wellhead stability is developed, and the impacts of hydrate formation on the stability of the subsea wellhead are analyzed. The gas source, temperature, pressure, solid surface roughness, and relative static subsea environment are found to be the key factors in the formation of hydrate in the marine environment. The risk of hydrate formation to wellhead stability is subtle, but to blowout preventer (BOP) could be significant. Hydrates may cause BOP control failure in which the BOP could not be closed in the event of emergency; hydrate formation between the BOP and the wellhead may cause BOP not to be separated from the bottom of the wellhead. A tool was designed for controlling the formation of hydrates, with particular tilt angle and surface roughness. Because the appropriate tilt angle can divert the gas bubbles to avoid the hydrate formations at the wellhead. The designed hydrate control tool successfully mitigates the risks to drilling operations.
- North America > United States (1.00)
- Asia > China (0.90)
- Well Drilling (1.00)
- Well Completion > Completion Installation and Operations (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Inhibition and remediation of hydrates, scale, paraffin / wax and asphaltene (1.00)
- Facilities Design, Construction and Operation > Flow Assurance > Hydrates (1.00)
A Systematic Reservoir Simulation Study on Assessing the Feasibility of CO2 Sequestration in Liquid-Rich Shale Gas Reservoirs with Potential Enhanced Gas Recovery
Zhan, Jie (University of Calgary) | Soo, Eric (Texas A&M University) | Fogwill, Allan (Canadian Energy Research Institute) | Cheng, Shiqing (China University of Petroleum) | Cai, Hua (CNOOC Ltd.) | Zhang, Kai (University of Calgary) | Chen, Zhangxin (University of Calgary)
Abstract The application of horizontal well drilling coupled with the multistage fracturing technology enables commercial development of shale gas formations, which launches the energy revolution from conventional resources to unconventional resources. Some of the shale reservoirs, particularly the Eagle Ford shale, contain a wide range of hydrocarbon fluids covering from low GOR black oil and volatile oil to the rich and lean gas-condensate. With the progress of understanding the nature of shale reservoirs, we find that some hydrocarbons are stored as an adsorbed phase on surfaces of organic carbon. Meanwhile, laboratory and theoretical calculations indicate that CO2 has significantly greater sorption capability compared with some lighter hydrocarbons like CH4 and C2H6. Shale gas reservoirs are recently becoming the promising underground target for CO2 sequestration. In the paper, systematic numerical simulations will be implemented to investigate the feasibility of CO2 sequestration in Eagle Ford liquid-rich shale gas reservoirs and quantify the associated uncertainties. First, a multi-continua porous medium model will be set up to present the matrix, nature fractures and hydraulic fractures in shale gas reservoirs. Based on the Eagle Ford gas condensate data, 14 components will be simulated in the compositional model. Meanwhile, we will investigate a three-stage flow mechanism which includes convective gas flow mainly in fractures, dispersive gas transport in macro pores and multi-component sorption phenomenon in micro pores. To deal with this complicated three-stage flow mechanism simultaneously, analytical apparent permeability which includes slip flow and Knudsen diffusion will be incorporated into a commercial simulator CMG-GEM. In addition, multicomponent adsorption/desorption lab data will be included in the model. A mixing rule is introduced to deal with the competitive adsorption phenomenon between the different components. In the paper, an integrated methodology is provided to investigate the CO2 sequestration process. Simulation results indicate that the Eagle Ford liquid-rich shale gas reservoir is an ideal target for the CO2 sequestration. To some extent, the average reservoir pressure is maintained due to injection of CO2. But most of the pressure is trapped around an injector due to the tight formation. That is why the reservoir productivity is enhanced by the injection process. But the increment is very small. Hydraulic fracking which creates freeways for gas flow is the key to improve the reservoir performance. The pressure maintenance around the injector reduces the effect of the liquid blockage, which is a good sign to implement the cyclic inert gas injection to reduce the effect of the liquid blockage and enhance the reservoir performance ultimately. The multicomponent desorption/adsorption is a very important feature in a shale gas reservoir, which should be fully harnessed to benefit the CO2 sequestration process. Meanwhile, the multicomponent desorption/adsorption process will increase the condensate production, which will lead to severer liquid blockage. In addition, it will limit the gas production. Furthermore, we cannot ignore the contribution of slip flow and diffusion to the reservoir performance during the sequestration process. Based on the methodology provided in this paper, we can easily deal with the apparent permeability effect based on a commercial simulator platform.
- Asia (0.93)
- North America > United States > Texas (0.49)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Sabinas - Rio Grande Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Maverick Basin > Eagle Ford Shale Formation (0.99)
- (4 more...)
An Integrated Multi-Scale Numerical Simulation of Transient Gas Flow in Shale Matrix
Zhan, Jie (University of Calgary) | Soo, Eric (Texas A&M University) | Fogwill, Allan (Canadian Energy Research Institute) | Cheng, Shiqing (China University of Petroleum) | Cai, Hua (CNOOC Ltd.) | He, Ruijian (University of Calgary) | Chen, Zhangxin (University of Calgary)
Abstract The gas flow in shale matrix is of great research interest for optimizing shale gas development. Due to a nano-scale pore radius, the gas flow in the shale matrix may fall in flow regimes which include viscous flow, slip flow and Knudsen diffusion. On top of that, gas adsorption/desorption and stress-sensitivity are some other important phenomena in shale. In this paper, we introduce an integrated multi-scale numerical simulation scheme to depict the above phenomena which is crucial for the shale gas development. Instead of Darcy's equation, we implement the apparent permeability in the reservoir-scale continuity equation to depict the gas flow (viscous flow, slip flow and Knudsen diffusion) in shale matrix. A Langmuir adsorption/desorption term is included in the reservoir-scale continuity equation as a generation term. To ensure the real-time desorption and adsorption equilibrium with gas production, an iterative mass balance check of pore wall surfaces (pore scale) is introduced. At each time step, the pore-scale and reservoir-scale mass balance should be satisfied simultaneously in each grid block. On top of that, the lab data of a Bakken reservoir which provides a relationship between a matrix pore radius reduction and the effective stress is integrated into the two-way coupling geomechanical process to simulate a stresssensitive shale formation. This methodology examines the influence of each mechanism for the shale gas flow in the matrix. Instead of conventional pressure-independent Darcy permeability, the apparent permeability increases with the development of a shale gas reservoir. With the gas adsorption/desorption, the reservoir pressure is maintained via the supply of released gas from nano-scale pore wall surfaces. With the consideration of geomechanics, the apparent permeability is decreased due to the compaction of nano-scale pore radii, which leads to the maintenance of reservoir pressure. Due to the difference of compaction magnitude for each grid block, geomechanics create additional heterogeneity for a nano-pore network in shale matrix, which we should pay more attention to. A novel integrated multi-scale methodology is introduced to examine the crucial phenomena in the shale matrix, which simultaneously takes into account the influence of flow regimes, gas adsorption/desorption and stress-sensitivity. An effective way is provided to quantify the above effects for the transient gas flow in shale matrix.
- North America > United States (1.00)
- Asia (0.94)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Reservoir Simulation (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management (1.00)
Geostatistical inversion based on zero-phase correction for thick-sand delineation: An application in Bohai Bay Basin
Gao, Wei (CNOOC Ltd.) | Guo, Jun (CNOOC Ltd.) | Zhang, Pingping (CNOOC Ltd.) | Li, Yao (CNOOC Ltd.) | Duan, Xin-Yi (CNOOC Ltd.)
ABSTRACT In Caofeidian X structure zone of Bohai Oilfield, thick sandbodies were generally developed in shallow layers. While, both traditional 90 ° phase rotation technique and constrained sparse pulse inversion were not suitable for a fine description of sand body. It was concluded that there existed reflection artifacts caused by non - zero phase of seismic data. The influence of phase angle on vertical resolution of seismic data was studied by carrying on numerical simulation of theoretical data and actual drilling data. According to this, this paper proposed a post-stack geostatistical inversion method based on zero-phase correction of seismic data. The inversion results effectively solved the three problems of the sand body depiction in our study area, which were the bifurcation of sand X-721, inaccuracy of the bottom of sand X-1400 and response weak of sand X-1470. The inversion results were in good agreement with actual drilling results, and the fine description of sand body was realized, which provided a strong support for sand body description work and built the foundation for reserve calculation. Hence this method can be also applied in other area. Presentation Date: Tuesday, September 26, 2017 Start Time: 3:55 PM Location: 350D Presentation Type: ORAL
- Geophysics > Seismic Surveying > Seismic Processing (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling > Seismic Inversion (0.49)
- South America > Argentina > Patagonia > Golfo San Jorge Basin (0.99)
- Asia > China > Bohai Basin (0.99)
Abstract Heavy oil reservoirs have became a key and difficult point as exploration and development of oil and gas goes deeper. Since deepwater heavy oil reservoirs are characterized by adverse fluid property and poor flowability resulting from low seawater temperature, conventional well test usually fails to gain expected crude sample and real formation data, leading to some problems for subsequent development. In view of two difficult issues during the deepwater heavy oil reservoirs test – flow assurance concern and decision-making difficulty in testing system, application of appropriate test technologies and techniques are of great importance. Prior to the offshore test, an integrated approach to modeling and designing operating conditions was described. The feasibility of available technical solutions in relation to enhancing the low wellhead temperature conditions was discussed based on the wellbore temperature and pressure features derived from the analytical modeling, and a test technique (integrated progressing cavity pump (PCP), heating sucker rod and insulated tubing) applicable to deepwater heavy oil reservoir was recommended. Then, drilling-stem test (DST) was carried out to an exploration well with two oil layers and one gas layer which is located in southwest of Congo sea with the recommended test technique. Simulation results demonstrate that the advantages of the compound technology – electric heating, PCP and insulated tubing are far greater than using insulated tubing or heating sucker rod alone. Compound technology decreases the frictional pressure loss of the producing fluid due to its capability of maintaining high and uniform wellbore temperature. Interactive tubing conveyed perforating (TCP) and DST was conducted with a testing program of thrice flow well and twice shut-in well. Insulated tubing assembly was employed from progressing cavity pump stator to the wellbore and the setting depth of the heated sucker rod was down to about 10m above the pump. Productivity information, representative crude samples and pressure/temperature information of the testing zone were obtained successfully. The simulation technology and pilot test proved the feasibility of insulated tubing and electric heating PCP in deepwater heavy oil testing, providing technical guidance for further appraisal and development of deepwater heavy oil fields.
- Asia > China (0.48)
- North America > Canada (0.29)