Oil production from shale and tight formations will increase to more than 6 million barrels per day (b/d) in the coming decade, making up most of total U.S. oil production (> 50%). However, achieving an accurate formation evaluation of shale faces many complex challenges. One of the complexities is the accurate estimation of shale properties from well logs, which is initially designed for conventional reservoirs. When we use the well logs to obtain shale properties, they often cause some deviations. Therefore, in this work, we combine cores and well logs together to provide a more accurate guideline for estimation of total organic carbon, which is primarily of interest to petroleum geochemists and geologists.
Our work is based on Archie's equation. Resistivity log will lead to some incorrect results, such as total resistivity, when we follow the conventional interpretation procedure in well logs. Porosity is another complex parameter, which cannot be determined only by well log, i.e. density, NMR, and Neutron log. Therefore, the flowchart of TOC calculation includes five main parts: (I) the shale content calculation using Gamma log; (II) the determination of shale distributions using Density and Neutron logs and cross-plot; (III) the calculation of total resistivity at different distribution types; (IV) obtaining porosity using core analysis, NMR and density logs; and (V) the calculation of TOC from modified Archie's equation.
The results indicate that the shale content has a strong effect on estimation of water saturation and hydrocarbon saturation. Especially, the effect of shale content is exacerbated at a low water saturation. A more accurate flowchart for TOC calculation is established. Based on Archie's equation, we modify total resistivity and porosity by combining Gamma Log, Density Log, Neutron Log, NMR Log, and Cross-plot. An easier way to estimate porosity is provided. We combine the matrix density and kerogen density together and obtain them from core analysis. Poupon's et al. (1954) laminar model has some limitations when applying in shale reservoirs, especially at a low porosity.
Literature surveys show few studies on the flowchart of TOC calculation in shale reservoirs. This paper provides some insights into challenges of well logs, core analysis in shale reservoirs and a more accurate guideline of TOC calculation in shale reservoirs.
Yu, Hao (Southwest Petroleum University, China) | Dahi Taleghani, Arash (Pennsylvania State University, United States) | Lian, Zhanghua (Southwest Petroleum University, China) | Lin, Tiejun (Southwest Petroleum University, China)
Microseismic data and production logs in our study area have confirmed an asymmetric development of the stimulation rock volume, while severe casing deformation problems have been reported frequently in this area. In this paper, we investigate the possibility of casing failure due to strong shear stresses developed by asymmetric stimulated zones. Overlapping stimulation zones in adjacent stages may intensify asymmetry of the pore pressure distribution and resultant shear forces. Although induced shearing may have a positive impact on fracture permeability, but it may also cause operational problems by inducing severe casing deformations. While most of the casing deformation models only consider rock deformations very close to the wellbore, we developed a 3D coupled model for fracture network growth and stress re-distribution during hydraulic fracturing to achieve a more realistic model for casing deformation. This reservoir-scale model is tied to a more detailed near-wellbore model including the casing and cement sheath to simulate casing deformations. Case studies were conducted using data from a shale gas well that experienced severe casing deformation during hydraulic fracturing. Impact of stage spacing, and pumping rate are incorporated to investigate their potential impacts on casing and well integrity. Multi-stage hydraulic fracturing considering the development of complex fracture network is simulated at the reservoir scale based on the microseismic events. Continuous re-distribution and re-orientation of stress field near the borehole are tracked during the development of the fracture network which reveals some pocket of tensile stresses along the casing. Asymmetric fractures are observed to generate strong shear stress on the suspended casing. These shear forces result in deflection and S-shape deformations. Some regions receive repeating treatments, which leads to increase formation stress heterogeneity and worsen casing deformation severity. Our analysis has indicated that simply increasing the flexural strength by increasing thickness of casing cannot radically mitigate casing deformation problems. This paper provides a novel workflow for a coupled modelling of casing deformation during hydraulic fracturing operations, while current modelling efforts assume symmetric fracture geometries.
Shale gas is a very important natural resource which can significantly affect the natural gas production of the world (e.g., in United States, Canada, and China). The organic matter within shale is the material that generates hydrocarbons, such as natural gas, under high thermal maturity. Throughout this process, a significant amount of pores within organic matter, called organic pore, are also generated, as the organic matter itself becomes a porous solid. These organic pores contribute significantly to the overall gas storage and flow of the reservoir as a whole. These organic pores are especially important to the process of gas adsorption and desorption within organic pores, which makes the storage and flow of shale gas very different from conventional reservoirs. The structure of organic pores, including pore volume, surface area, geometry, size distribution, etc., is significant to understanding their influence upon gas adsorption and desorption and gas flow. Thus, it is necessary to quantitatively analyze these organic pores; however, studies that quantitatively analyze organic pore structure in detail are rare. By better understanding characteristics and relationships of these pores through statistical analysis, it is possible to be able to ascertain more characteristics of the reservoir as a whole. Therefore, this research aims to develop the quantitative method to characterize pore structure and discuss the feature of pore structure of high-maturity shale samples from the Sichuan Basin.
Dong, Xuemei (Research Institute of Geophysical, Research Institute of Exploration and Development, PetroChina Xingjiang Oilfield Company) | Zhang, Ting (Surignan Operating Company, PetroChina Changqing Oilfield Company) | Yao, Weijiang (Research Institute of Geophysical, Research Institute of Exploration and Development, PetroChina Xingjiang Oilfield Company) | Hu, Tingting (Research Institute of Geophysical, Research Institute of Exploration and Development, PetroChina Xingjiang Oilfield Company) | Li, Jing (Research Institute of Geophysical, Research Institute of Exploration and Development, PetroChina Xingjiang Oilfield Company) | Jia, Chunming (Research Institute of Geophysical, Research Institute of Exploration and Development, PetroChina Xingjiang Oilfield Company) | Guan, Jian (Research Institute of Geophysical, Research Institute of Exploration and Development, PetroChina Xingjiang Oilfield Company)
Pore structure is of great importance in tight reservoirs identification and validation evaluation, especially for formations with developed fractured. However, the conventional pore structure evaluation method based on nuclear magnetic resonance (NMR) logging lost its role. This is because the fractures with width lower than 2mm did not have response in the NMR T2 spectrum. Whereas the porosity spectrum, which extracted from the FMI data, was considered to be effective in fractured reservoir pore structure evaluation. In this study, to quantitatively characterize tight glutenite reservoir pore structure in the Jiamuhe Formation in northwest margin of Junggar Basin, northwest China, 90 core samples were drilled for lab mercury injection capillary pressure (MICP) measurement, and the XRMI data (acquired by the Halliburton and be similar with FMI) was processed to acquire the porosity spectrum.
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.
If you can see it, then maybe you can control it. This sums up the latest quest that the unconventional engineering community embarked upon to get a better understanding of proper well spacing and how fractures really interact. The Unconventional Resources Technology Conference is like visiting an oilfield theme park for engineers and geoscientists. This year those traveling to the conference for a glimpse of what is possible in exploration and production will also focus on ways to improve short-term profitability. The new milestone was reached less than a year after the country surpassed 11 million B/D last summer, and is driven by activity in the Permian Basin and new fields in the Gulf of Mexico.
Petrobras and Shell have brought online the Lula field’s seventh FPSO as the firms continue to ramp up production from the pre-salt Santos Basin. The national oil company’s aim to lift oil and gas production and reserves over the next few years will rely on growth from big international projects, including those in Nigeria, Guyana, and the US. Majors BP and Chevron have overcome development challenges and delays to launch their respective Clair Ridge and Big Foot projects. The unit is flowing oil and gas from the Lula Extremo Sul area, 290 km off Rio de Janeiro state in 2150 m of water. The $28-billion Shah Deniz Phase 2 project off Azerbaijan will supply gas to Europe through the Southern Gas Corridor pipeline system.
This paper discusses a study undertaken to gain better understanding of nuclear magnetic resonance (NMR) characteristics of volcanic reservoirs with different lithologies. My visit to China consisted of some very substantial meetings with the members from the SPE Beijing Section as well as the Northern China International Section. As the country pushes for higher output from its emerging unconventional sector, nature is pushing back. To get better results, operators there are increasing their reliance on technology. This paper discusses the successful application of managed-pressure drilling (MPD) in the basin with reduction in risks and well costs.
Green fields today mostly can be regarded as marginal fields and successfully developed. It covers the complete assessment of the oil and gas recovery potential from reservoir structure and formation evaluation, oil and gas reserve mapping, their uncertainties and risks management, feasible reservoir fluid depletion approaches, and to the construction of integrated production systems for cost effective development of the green fields. Depth conversion of time interpretations is a basic skill set for interpreters. There is no single methodology that is optimal for all cases. Next, appropriate depth methods will be presented. Depth imaging should be considered an integral component of interpretation. If the results derived from depth imaging are intended to mitigate risk, the interpreter must actively guide the process.
PETRONAS FLNG SATU (PFLNG1) is a floating liquefied natural gas facility producing 1.2 million tonnes per annum (mtpa) of LNG, on a facility that is 365m long, and 60m wide, making it among the largest offshore facility ever built. The PFLNG1 project is the first of its kind in the world and is the first deployment of PETRONASâ€™ Floating Liquefied Natural Gas (FLNG) technology, consolidating the traditional offshore to onshore LNG infrastructure into a single facility. This will see a giant floating facility capable of extracting, liquefying and storing LNG at sea, before it is exported to customers around the globe. The FLNG journey has come a long way since 2006, with many technological options explored to monetise and unlock the potential of small and stranded gas fields. Moving an LNG production to an offshore setting poses a demanding set of challenges â€“ as every element of a conventional LNG facility needs to fit into an area roughly one quarter the size in the open seas whilst maintaining safety and increased flexibility to LNG production and delivery. The keynote address describes the breakthrough features of PFLNG1 â€“ the worldâ€™s first floating LNG facility; and the pioneering innovation that it brings to the LNG industry.