This seminar will teach participants how to identify, evaluate, and quantify risk and uncertainty in everyday oil and gas economic situations. It reviews the development of pragmatic tools, methods, and understandings for professionals that are applicable to companies of all sizes. The seminar also briefly reviews statistics, the relationship between risk and return, and hedging and future markets. Strategic thinking and planning are key elements in an organisation’s journey to maximise value to shareholders, customers, and employees. Through this workshop, attendees will go through the different processes involved in strategic planning including the elements of organisational SWOT, business scenario and options development, elaboration of strategic options and communication to stakeholders.
Decisions in E&P ventures are affected by Bias, Blindness, and Illusions (BBI) which permeate our analyses, interpretations and decisions. This one-day course examines the influence of these cognitive pitfalls and presents techniques that can be used to mitigate their impact. Bias refers to errors in thinking whereby interpretations and judgments are drawn in an illogical fashion. Blindness is the condition where we fail to see an unexpected event in plain sight. Illusions refer to misleading beliefs based on a false impression of reality.
Liang, Xing (PetroChina Zhejiang Oilfield) | Wang, Gao-Cheng (PetroChina Zhejiang Oilfield) | Pan, Feng (Schlumberger) | Rui, Yun (PetroChina Zhejiang Oilfield) | Wang, Yue (Schlumberger) | Zhang, Lei (PetroChina Zhejiang Oilfield) | Mei, Jue (PetroChina Zhejiang Oilfield) | Li, Kai-Xuan (Schlumberger) | Zhao, Hai-Peng (Schlumberger)
Understanding mineral composition and depositional mechanisms aids in evaluating gas in place and mechanical properties of shale reservoirs. A method developed to delineate mineral variations and depositional setting combines borehole elemental concentration logs with borehole electrical image logs. Borehole elemental concentration logs provide a continuous measurement of the concentrations of more than 20 elements, which data help in obtaining quantities of mineralogical constituents. Electrical borehole images are used to identify in situ depositional features. Regional mapping of variations of mineral constituents and depositional features indicates sedimentary facies distribution.
The Lower and Upper WuFeng-LongMaxi Formation was studied in 27 wells spanning 100 km west-east across the southern SiChuan basin. From elemental spectroscopy, argillaceous, carbonate, and siliceous lithologies were identified; these were examined by scanning electron microscope (SEM) to investigate their mineralogy and geological origin. Argillaceous minerals were primarily supplied by terrigenous sediments, the majority of carbonate minerals originated from chemical precipitation, and siliceous minerals are associated with siliceous-shell organisms in the Lower WuFeng-LongMaxi strata and terrigenous influx in the Upper LongMaxi strata. A transgressive lag occurring at the base of the WuFeng formation corresponds to carbonate pebbles in cores and bedding-parallel gravels on borehole images. Silty layers deposited by turbidity currents that mainly appear in Upper LongMaxi Formation were readily identified on borehole images.
Jiang, Li-Wei (PetroChina Zhejiang Oilfield Company) | He, Yong (PetroChina Zhejiang Oilfield Company) | Shu, Dong-Chu (PetroChina Zhejiang Oilfield Company) | Niu, Wei (PetroChina Zhejiang Oilfield Company) | Pan, Feng (Schlumberger) | Wang, Yue (Schlumberger) | Li, Kai-Xuan (Schlumberger) | Zhao, Hai-Peng (Schlumberger) | Tang, Yu (PetroChina Southwest Oil and Gas Company)
Most bedding-parallel fractures in the WuFengLongMaxi Formation, SiChuan basin, are calcite filled and commonly show slickensides, which features characterize bedding-parallel shear fractures. Such fractures can serve as flow channels and storage spaces in gas shale reservoirs. However, little is known about their size and spatial distribution, the relationship of their permeability to the confining stress, and any relationship with porosity. Knowing these relationships may contribute to understanding the role of bedding-parallel shear fractures in shale gas enrichment.
Bedding-parallel shear fractures were measured from core and image logs from the WuFeng-LongMaxi Formation, southern SiChuan basin, supplemented with stress-dependent permeability experimental data and nuclear magnetic resonance (NMR) logs from the same wells. Core and image logs were used to characterize the spatial organization of the fractures. A stress-dependent permeability experiment was proposed to investigate the fracture permeability response to changes in confining stress. The effect of the fractures on porosity was examined in terms of the macroporous component reflected by the NMR T2 relaxation; macropores are more likely to be preserved in gas-rich shale. Study of 27 wells spanning 100 km west-east across the southern SiChuan basin revealed the aperture size of bedding-parallel shear fractures ranges from 1 cm to 50 cm. In most wells, the fractures are much more intense in organic-rich intervals, which have low elastic modulus compared to the overlying nonorganic shale and underlying stiff limestone. The stress-dependent permeability experiment suggests that permeability in samples with the fractures is two to three orders of magnitude larger than in samples without fractures under the same confining stress. Fracture permeability decreases exponentially until the confining stress reaches 25 MPa. NMR analysis indicates that the macroporous component has an inverse relationship with the intensity of bedding-parallel shear fractures.
Tian, Hua (Research Inst Petr Expl & Dev, Petrochina) | Zou, Caineng (Research Inst Petr Expl & Dev, Petrochina) | Liu, Shaobo (Research Inst Petr Expl & Dev, Petrochina) | Zhang, Shuichang (Research Inst Petr Expl & Dev, Petrochina) | Lu, Xuesong (Research Inst Petr Expl & Dev, Petrochina) | Ma, Xingzhi (Research Inst Petr Expl & Dev, Petrochina) | Bi, Lina (Research Inst Petr Expl & Dev, Petrochina) | Yuan, Miao (Research Inst Petr Expl & Dev, Petrochina)
A series of petrohysical experiments have been conducted to obtain the gas physical properties (e.g., gas-water interfacial tension). The capillary pressures of pore throats were obtained through numerical calculation. Furthermore, residue water was used to calculate gas/water saturation in the reservoirs. The gas saturation variation under lower interfacial tension and the amount of gas lost during the uplift in burial history need an in-depth examination (Tian et al., 2017). In addition to the geological studies in the field, various laboratory methods were used to tackle the problems mentioned above, including Nlear nuclear magnetic resonance (NMR) and fluid inclusion analysis with optical and Laser Raman spectroscopy. During the charging history, hydrcarbon saturations at different temperature and pressure was calculated using the model established in this paper, which is mainly determined by the pore size distribution obtained by the NMR analysis. The charging pressure is measured by fluid inclusion study with optical and Laser Raman spectroscopy test. Furthermore, the leakage content of gas during the burial history was calculated using a diffusion model (Krooss& Leythaeuser., 1988; Krooss et al., 1992).
Chen, Changzhao (State Key Laboratory of Petroleum Pollution Control, CNPC Research Institute of Safety and Environmental Technology) | Li, Xingchun (China University of Petroleum) | Wu, Baichun (State Key Laboratory of Petroleum Pollution Control, CNPC Research Institute of Safety and Environmental Technology) | Zhang, Kunfeng (State Key Laboratory of Petroleum Pollution Control, CNPC Research Institute of Safety and Environmental Technology) | Song, Quanwei (State Key Laboratory of Petroleum Pollution Control, CNPC Research Institute of Safety and Environmental Technology)
The world has seen a peak in unconventional gas development in recent years. Based on the practice of unconventional gas field development domestic in China and abroad, it is risky that the reinjection water may contaminate groundwater in local or adjacent areas during reinjected fluid migration. Ensuring environmental safety of the reinjection is a multi-disciplinary system project. This paper carries out the analysis and shares the experience of China's practice based on the actual cases from the following aspects. 1) The screening of the well location and the formation of the reinjection. 2) The drilling and cementing construction of the reinjection well, which considers the factors such as cementing quality and cement height and casing material. 3) The estimation of the total reinjection capacity, and the factors such as porosity and permeability of the geologic trap and reservoir fracture pressure is considered. 4) The monitoring of well and migration of reinjection fluids. Further environmental risk study of produced water reinjection is presented in this paper, on both sandstone formation of tight sand gas field and carbonate karst formation of shale gas field in China's typical unconventional gas development areas, using laboratory geochemistry experiments and large area geophysical test to obtain seismic data.
Zheng, Ma Jia (Southwest petroleum University) | Liu, Xin (Schlumberger Technology Services, Chengdu, Ltd) | Zhao, Jian Ping (PetroChina Southwest Oil and Gas Field Company) | Qiu, Xun Xi (Sichuan Shale Gas Exploration and Development Company Ltd) | Fang, Jian (CCDC Geological Exploration & Development Research Institute) | Wang, Xiong Fei (Schlumberger Technology Services, Chengdu, Ltd) | Zhao, Jing Kai (Schlumberger Technology Services, Chengdu, Ltd) | Geng, Gan (Schlumberger Technology Services, Chengdu, Ltd)
The Sichuan Basin is the major target for shale gas exploration in China because of its rich gas stored in unexploited black shale with multiple bed series. National Shale Gas Exploitation Areas have been established since 2012, the proved geological shale gas reserves is 9210×108 m3 and 90.25×108m3 annually output has been achieved by the end of 2017.
The operating Sichuan Basin shale gas area located in the major compression tectonic experienced multiple geological structure movements in Earth history, showing characteristics of high steep structure with faults greatly developed. It's proven that the key factors in exploiting these targets are well acknowledged by the efforts to land and expose the lateral within the sweet zone. To successfully place lateral in reservoirs from geological perspective must overcome challenges of high uncertainty structure identification to make soft landing and maximize horizontal exposure in the sweet zone.
While it comes to shale gas reservoir, to pave the way for fracture operation and achieve good well completion, the drilling requires a relative gentle well path, keeping well path inclination with limitation, which requires to make azimuth turning to achieve this.
To ensure the optimum placement of the well in sweet zone, the integration of rotary steerable drilling system (RSS) with borehole images measurements in real-time have been implemented with the employment of well placement technique.
The borehole image portrays structural profile while drilling whilst the rotary steerable drilling system provides accurate trajectory control. With the help of borehole image and proactive log correlation, the trajectory can be landed precisely into desired best quality reservoir, although the formation dip and actual target depth become much different with geological prognosis. During the lateral section, the trajectory was also controlled effectively in the high-quality reservoir despite of structural variation and reservoir property change. Through use of Fit-For-Purpose solution it effectively improves drilling efficiency and positively impacts well production. These achievements subsequently help to optimize wells deployment plan and wells with longer lateral horizontal section were planned for greater predictable production rate.
Xue, Ming (State Key Laboratory of Petroleum Pollution Control, CNPC Research Institute of Safety and Environmental Technology) | Fan, Jun-xin (State Key Laboratory of Petroleum Pollution Control, CNPC Research Institute of Safety and Environmental Technology) | Weng, Yi-bin (State Key Laboratory of Petroleum Pollution Control, CNPC Research Institute of Safety and Environmental Technology) | Cui, Xiangyu (State Key Laboratory of Petroleum Pollution Control, CNPC Research Institute of Safety and Environmental Technology) | Li, Xing-chun (State Key Laboratory of Petroleum Pollution Control, CNPC Research Institute of Safety and Environmental Technology)
Objectives/Scope: Greenhouse gas emission (carbon dioxide and methane, etc.) during shale gas production could decide whether it is a cleaner energy source than coal. However, the methane and carbon dioxide emission from flowback process during shale gas production remains unclear. The withdrawn of fracture water both from underground and surface water, and the relatively high gas pressure from the wellhead have made flowback water highly potential as a significant greenhouse gas emission source.
Methods, Procedures, Process: In this study, the estimation of greenhouse emission potential was provided based on the flowback water samples collected from shale production sites of China. The buffer capacity of carbon dioxide was estimated based on the parameters measured including temperature, pressure, conductivity, salinity, dissolved inorganic carbon (DIC), pH, chloride etc. The possible methane emission was also estimated based on the solution/dissolution curve from gas-water equilibrium during the flowback process.
Results, Observations, Conclusions: The results showed that: the relatively high salinity of the flowback water has provided a considerable buffer capacity for carbon dioxide. The water residence time in the water tank/pond largely determines air-water greenhouse flux. When the flowback water pass through the three-phase separator to the water outlet, the dissolution capacity of methane reduced sharply dropped. By switching to a higher water level in the separator, methane emission could be reduced. However, a higher water vapor ratio may be detected in the gas phase, as well. Besides the fugitive methane emission from pneumatic pumps, valves, etc., greenhouse gas emission from flowback water is a significant source which needs to be reduced in future shale gas production.
Novel/Additive Information: The determination of greenhouse gas emission from flowback could better defined the life cycle of shale gas, while provide baseline analysis for the development of greenhouse gas control technology during flowback water treatment and three-phase separator optimization.
Zhai, Wenbao (China University of Petroleum) | Li, Jun (China University of Petroleum) | Xi, Yan (China University of Petroleum) | Liu, Gonghui (China University of Petroleum) | Yang, Hongwei (China University of Petroleum) | Jiang, Hailong (China University of Petroleum) | Zhou, Yingcao (CNPC Engineering Technology R&D Company Limited)
Shale reservoir heterogeneity is more and more focused during shale gas development, especially deep shale gas reservoir buried in the depth of over 3,500 m. However, the evaluation methods of heterogeneity are not always available and poor applicability. In this study, a Principle Component Analysis (PCA)-Artificial Neural Network (ANN) model was presented. The evaluation steps of the model were also given. The validation of the model was confirmed by using a deep shale gas well located in Weiyuan area of Sichuan Basin, China. The results of the validation show that the model presented in this study can be in good agreement with the assessed values of heterogeneity obtained from microseimic events. The developed model's effectiveness was tested by comparing the results acquired from ANN without PCA, where the PCA reduces the dimension of input parameters to improve results of PCA-ANN over 80%. Therefore, the PCA-ANN model can help the engineers evaluate the deep shale reservoir heterogeneity, which provides a tool to give preliminary recommendations of the likelihood of improving the effectiveness of hydraulic fracturing. Implementation of the proposed model can serve as a cost-effective and reliable alternative for the deep shale reservoir.
Chen, Xiaoer (Institute of Sedimentary Geology, Chengdu University of Technology, Geophysical Technology Research Centre, BGP, CNPC) | Fan, Kun (Southwest Geophysical Research Institute, BGP, CNPC) | Ren, Chenghao (Southwest Geophysical Company, BGP, CNPC) | Li, Le (Geophysical Technology Research Centre, BGP, CNPC) | Yan, Zhenqian (Sichuan Institute of Coral Field Geological Engineering Exploration and Designing) | Zou, Guoliang (Exploration Department of Changqing Oilfield LTD, CNPC) | Cao, Zhonglin (Geophysical Technology Research Centre, BGP, CNPC) | Zhao, Yao (Geophysical Technology Research Centre, BGP, CNPC)
The Cambrian Longwangmiao Formation in the Sichuan Basin, southwest China, mainly comprising of dolomites, is one of the most ancient production layer in the world. Recently, Anyue gas field was discovered in the Leshan-longnvsi paleo-uplift in the central Sichuan Basin, and become the oldest gas field in the carbonate rocks in a single structural system in China. The reservoir is mainly distributed in the shoal grain dolomite, which is always controlled by the sedimentary environment. The conventional well correlation and sedimentary facies analysis might result in difficulty of carbonate shoals distribution and reservoir description in the gas field. Hence, how to characterize the geometry and distribution of carbonate shoals is critical for gas exploration and development. In our study, we completed an interpretation of 1172km2 3D seismic data in the field by means of all reflectors auto-tracking method. The method, combining density-based spatial clustering with waveform similarity clustering algorithm, can automatically track and interpret all reflectors within the 3D seismic cube. As a result, 18 local horizons, characterized by a shingled progradational configuration, were recognized within the Longwangmiao Formation. Synthetic seismograms suggest that these parallel oblique progradational sets were considered as carbonate shoals. The Longwangmiao Formation is consisted of stacked multistaged carbonate grainstones deposited on the shoals within the platform. These shoals, which grow towards northwest, are approximately distributed surrounding the Leshan-Longnvsi paleo-uplift. Stacked and widely distributed shoal grainstone reservoir is formed on the uplift. Our study suggests that the paleo-uplift mainly controls the shoal distribution in the study area, which provides important clues for gas exploration.