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Reservoir protection strategy in drilling stage of Tarim oilfield
Published in Ahmad Safuan Bin A Rashid, Junwen Zhang, Advances in Mineral Resources, Geotechnology and Geological Exploration, 2023
Hongtao Liu, Yang Zhang, Shenglan Tang, Yan Qiao, Lihu Cao, Shiling Zhang, Hongjun Wu, Sun Tao
Reservoir damage mechanism: the damage mechanism and causes of drilling fluid to the reservoir are analyzed as follows:The matrix is dense, the solid particles are difficult to enter the formation, and the formation particles cannot migrate, so the particles have little impact on the reservoir damage;Leakage easily occurs in the drilling stage, and a large number of drilling fluid phases will enter the karst cave with rich formation fluid. However, whether the drilling fluid leakage causes damage to the cave in the reservoir and the degree of damage cannot be experimentally evaluated.The pressure difference between the drilling fluid column and the formation pressure will not cause stress sensitivity damage in the drilling stage, but the excessive pressure difference acting on the reservoir will increase the risk of drilling fluid leakage and cause drilling fluid leakage damage. Therefore, attention should be paid to reservoir protection.
An electro-chemo-mechanical mixture formulation of shale
Published in C. Di Maio, T. Hueckel, B. Loret, Chemo-Mechanical Coupling in Clays, 2018
In general each drilling fluid contains chemicals and solids, designed to facilitate mud weight control, hole cleaning and drill-string lubrication. The solids form a filter-cake on the borehole wall, which prevents communication of the drilling fluid with the formation fluid.
Temperature distribution of shale oil wellbore considering oil-based mud and formation fluid displacement
Published in Journal of Dispersion Science and Technology, 2023
Wen Yin, Yun Lei, Song Deng, Meng Cui, Shoukun Xu, Jiangshuai Wang, Lin Shi, Haoping Peng, Fei Zhao
With the increase of conventional energy consumption around the world, the development of clean and efficient unconventional energy is in high demand.[1–4] As a new form of clean energy, shale oil has become a research highlight internationally, which features stable distribution, large thickness and wide distribution.[5] China is rich in continental shale oil resources, and the development and utilization of unconventional resources such as shale oil is an important to achieve China’s "energy independence". In the past decades, organic-rich shale has regained the attention of explorers and researchers. As an important field of unconventional oil and gas exploration, shale oil has huge resource potential.[6–7] However, in some areas, shale formation fractures and faults are developed, especially when the wellbore leakage phenomenon occurs after annulus-formation fluid displacement.[8–10] After the annulus is replaced with the formation fluid, the density and rheology of the drilling fluid in the wellbore are no longer constant, but change with the temperature.[11–13] Whether to describe the variation law of the temperature in the wellbore along the well depth under the replacement condition accurately is vital to the drilling project,[14] therefore, it is necessary to systematically analyze the characteristics and influence laws of the displacement phenomenon between the annulus and the formation fluid.
Damage-control technology of oil-based drilling fluid for Kuqa piedmont structure
Published in Geosystem Engineering, 2018
Peng Xu, Zhengwu Tao, Xiao Liu, Zhihang Yan, Mingbiao Xu
Based on existing research and oilfield data, several factors may lead to formation damage, such as wettability change, solid-phase particle plugging, oil-wet particle migration, oil trapping, internal bubble filling of drilling fluid, these all are usually ignored in engineering. Cui, Shen, Lei, and Shu (2012) thought that organic soil, wetting agent and other agents had damage to formation, but the damage would decrease when these agents form a system, damage coefficient was not a simple superposition of components. Bahrami, Rezaee, Saeedi, and Murikhan (2012) thought that oil-based drilling fluid filtrate and formation fluid formed a mixture, and caused oil trapping. Tsar et al. (2012) considered that pore capillary fore and pore throat distribution would change, and formed oil trapping damage when oil-based drilling fluid flowed into formation. Lashari et al. (2013) confirmed trapping damage of oil-based drilling fluid was less than water-based drilling fluid. Thomas, Hsing, and Menzie (1984) considered that organic soil was an oil-wet bentonite and could be fully dispersed in oil, and it was easier to enter the micro cracks than bentonite. Skalli, Buckley, Zhang, and Morrow (2006) thought that wettability change was mainly due to the interaction between polarity components and rock surface after drilling fluid contact with water-wet rock. Growcock, Khan, and Simon (2003) thought that tiny bubbles in oil-based drilling fluid would cause jamin effect to reduce the invasion of drilling fluid filtrate, thus reducing the damage of oil-based drilling fluid.
A study on identification of borehole ballooning in the formation with narrow safe density window
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2019
Cheng Li, Zhichuan Guan, Bo Zhang, Yanan Sheng, Qing Wang, Xiaohui Wang, Chao Han
In the first diagram on the right side of Figure 2, ECD theoretically can decrease the value measured on the ground right away after pumping off, but it is a little higher in fact due to the compressibility of drilling fluid. In the second diagram, the backflow of the previous leakage when borehole ballooning happens could slow down the decreasing and increasing speed. The third diagram shows the case when well kick happens. Because the annular drilling fluid mixes with formation fluid, ECD is lower than the density of drilling fluid measured on the ground during pumping off.