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By benchmarking with the iteration of drilling technology, fracturing technology and well placement mode for shale oil and gas development in the United States and considering the geological characteristics and development difficulties of shale oil in the Jiyang continental rift lake basin, East China, the development technology system suitable for the geological characteristics of shale oil in continental rift lake basins has been primarily formed through innovation and iteration of the development, drilling and fracturing technologies. The technology system supports the rapid growth of shale oil production and reduces the development investment cost. By comparing it with the shale oil development technology in the United States, the prospect of the shale oil development technology iteration in continental rift lake basins is proposed. It is suggested to continuously strengthen the overall three-dimensional development, improve the precision level of engineering technology, upgrade the engineering technical indicator system, accelerate the intelligent optimization of engineering equipment, explore the application of complex structure wells, form a whole-process integrated quality management system from design to implementation, and constantly innovate the concept and technology of shale oil development, so as to promote the realization of extensive, beneficial and high-quality development of shale oil in continental rift lake basins.

Heavy oil represents a vital petroleum resource worldwide. As one of the major producers, China is facing great challenges in effective and economic production of heavy oil due to reservoir complexity. Plenty of efforts have been made to promote innovative advances in thermal recovery modes, methods, and processes for heavy oil in the country. The thermal recovery mode has been shifted from simple steam injection to a more comprehensive “thermal+'' strategy, such as a novel N2-steam hybrid process and CO2-enhanced thermal recovery techniques. These advanced techniques break through the challenges of heavy oil extraction from less accessible reservoirs with thinner oil layers and greater burial depths. Regarding thermal recovery methods, China has developed the steam-assisted gravity drainage method integrating flooding and drainage (also referred to as the hybrid flooding-drainage SAGD technology) for highly heterogeneous ultra-heavy oil reservoirs and the fire flooding method for nearly depleted heavy oil reservoirs, substantially improving oil recovery. Furthermore, a range of processes have been developed for heavy oil production, including the open hole completion process using sand control screens for horizontal wells, the process of integrated injection-recovery with horizontal pump for horizontal wells, the steam dryness maintenance, measurement, and control process, efficient and environment-friendly circulating fluidized bed (CFB) boilers with high steam dryness, the recycling process of produced water, and the thermal recovery process for offshore heavy oil. Based on the advances in methodology, technology, and philosophy, a series of supporting technologies for heavy oil production have been developed, leading to the breakthrough of existing technical limit of heavy oil recovery and the expansion into new exploitation targets. For the future heavy oil production in China, it is necessary to embrace a green, low-carbon, and energy-efficient development strategy, and to expand heavy oil extraction in reservoirs with larger burial depth, more viscous oil, thinner oil layers, and lower permeability. Moreover, it is highly recommended to collaboratively maximize oil recovery and oil-to-steam ratio through technological innovations, and boost intelligentization of heavy oil production.

In the Jiaoshiba block of the Fuling shale gas field, the employed reserves and recovery factor by primary well pattern are low, no obvious barrier is found in the development layer series, and layered development is difficult. Based on the understanding of the main factors controlling shale gas enrichment and high production, the theory and technology of shale gas three-dimensional development, such as fine description and modeling of shale gas reservoir, optimization of three-dimensional development strategy, highly efficient drilling with dense well pattern, precision fracturing and real-time control, are discussed. Three-dimensional development refers to the application of optimal and fast drilling and volume fracturing technologies, depending upon the sedimentary characteristics, reservoir characteristics and sweet spot distribution of shale gas, to form “artificial gas reservoir” in a multidimensional space, so as to maximize the employed reserves, recovery factor and yield rate of shale gas development. In the research on shale gas three-dimensional development, the geological + engineering sweet spot description is fundamental, the collaborative optimization of natural fractures and artificial fractures is critical, and the improvement of speed and efficiency in drilling and fracturing engineering is the guarantee. Through the implementation of three-dimensional development, the overall recovery factor in the Jiaoshiba block has increased from 12.6% to 23.3%, providing an important support for the continuous and stable production of the Fuling shale gas field.

Abstract CO2 EOR (enhanced oil recovery) will be one of main technologies of enhanced unconventional resources recovery. Understanding effect of permeability and fractures on the oil mobilization of unconventional resources, i.e. tight oil, is crucial during CO2 EOR process. Exposure experiments based on nuclear magnetic resonance (NMR) were used to study the interaction between CO2 and tight oil reservoirs in Chang 8 layer of Ordos Basin at 40 °C and 12 MPa. Effect of permeability and fractures on oil mobilization of exposure experiments were investigated for the different exposure time. The oil was mobilized from matrix to the surface of matrix and the oil recovery increased as the exposure time increased. The final oil recovery increased as the core permeability increased in these exposure experiments. Exposure area increased to 1.75 times by fractures resulting in that oil was mobilized faster in the initial stage of exposure experiment and the final oil recovery increased to 1.19 times from 28.8 to 34.2%. This study shows the quantitative results of effect of permeability and fractures on oil mobilization of unconventional resources during CO2 EOR, which will support CO2 EOR design in Chang 8 layer of Ordos Basin.

Different from the mechanism of improving light oil recovery by CO2 injection, heavy oil does not mix with CO2, so the main factors affecting its development are very different. Especially in the process of thermochemical composite oil recovery, the injected CO2 mainly plays a role in insulating heat, reducing viscosity and increasing energy. The properties of heavy oil were determined in this study in order to systematically investigate the effects of different factors influencing CO2 displacement. The effect of heavy oil viscosity, temperature, pressure and permeability on recovery were investigated using the orthogonal experimental method. Temperature was the most significant factor, followed by permeability, pressure and heavy oil viscosity. According to the experimental results and considering factors such as reservoir temperature and permeability, the field tests of CO2 huff and puff in the Shengli Oilfield of SINOPEC were conducted. Production results show that increasing reservoir temperature and permeability is beneficial for CO2 EOR and can improve oil production.