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Shaft Drilling and Pile Driving
Published in John E. Schaufelberger, Giovanni C. Migliaccio, Construction Equipment Management, 2019
John E. Schaufelberger, Giovanni C. Migliaccio
When constructing drilled concrete shafts, maintaining the stability of the excavation during concrete placement is vital in assuring a structurally sound shaft. Dry placement can only be performed when the soil is inherently stable when cut, such as clay or rock, and when ground water is not present. If any ground water makes its way into the excavation, the soil walls can degrade reducing the structural capacity of the shaft. When constructing a shaft under wet conditions, a slurry is placed in the excavation to maintain a net positive pressure against the walls of the excavation. The excavation wall stability can also be maintained using a casing. A casing is a thin-walled steel pipe that is slightly larger than the drilling diameter. The casing is driven, vibrated, or oscillated into position prior to excavation. Typically, the temporary casing is removed as the concrete placed. Sometimes the design requires installation of permanent casings.
Drilling and Completions
Published in Chun Huh, Hugh Daigle, Valentina Prigiobbe, Maša Prodanović, Practical Nanotechnology for Petroleum Engineers, 2019
Chun Huh, Hugh Daigle, Valentina Prigiobbe, Maša Prodanović
Good cement integrity is essential for safe completion and production operations, as the cement between casing and formation prevents borehole collapse, holds the casing in place, and prevents flow between subsurface formations. In a report on well control incidents (blowouts) on the outer continental shelf of the US, the Minerals Management Service stated that, between 1992 and 2006, “[t]he most significant factors included cementing problems resulting in gas migration during or after cementing of the well casing” (Izon et al. 2007). Poor cement integrity has been cited as a contributing factor in the 2010 blowout of the Macondo well (National Academy of Engineering 2011), and presents a significant risk factor for migration of gas to the surface, with corresponding environmental and safety risks (Ingraffea et al. 2014; Watson and Bachu 2009). Cement with good integrity should have low permeability, high tensile and compressive strengths, and a relatively low Young’s modulus to accommodate in-situ shear deformation without failure (Santra et al. 2012). These properties may be controlled with chemical additives. The role of nanoparticles in improving cement properties has garnered interest in industry for several years and is the subject of a number of patents (e.g., Roddy 2016; Roddy et al. 2009, 2013).
Seismic Source Monitoring with Compressive Sensing
Published in C.H. Chen, Compressive Sensing of Earth Observations, 2017
Ismael Vera Rodriguez, Mauricio D. Sacchi
The monitoring array in this example consists of 1082 vertical component receivers spread over 10 surface lines (Figure 9.6a). The target well is approximately vertical down to the target rock formation, where it turns horizontal over a distance on the order of 1 km (see Figure 9.6). The wellbore is isolated from the surrounding rock formations with a series of steel casings. The purpose of the casing is to ensure that the fluids flowing from the hydraulic fracture toward the well travel directly to the surface without leaking back into a different rock formation. At the position along the well where the hydraulic treatment is desired, a set of perforation shots are fired to pierce the casing. The perforations open communication paths between the well and the target formation and also act as initiation points for the hydraulic fracture. In this case, the casing was perforated in three contiguous locations separated by 30 m intervals at a vertical depth of –2000 m (see Figure 9.6).
Study on water-based epoxy resin cementing fluid system
Published in Journal of Dispersion Science and Technology, 2023
Xiaoying Wu, Yongjin Yu, Jun Zhao, Chi Zhang, Mingdan He, Ming Li
Cementing is to run a layer of casing into the well to a certain depth, and then inject cement slurry between the casing and the borehole to seal.[1] Cement slurry forms cement sheath after hardening, and its main function is to seal off formation and support casing.[2,3] However, due to the brittleness, poor deformability and mechanical properties of the cement sheath, when subjected to external load, it is easy to produce micro cracks and gaps in the interior or surface, which will lead to the destruction of the integrity of the cement sheath, the loss of interlayer isolation and the channeling of oil, gas and water.[4–6] Therefore, it would be worthwhile to investigate the use of water-based epoxy resin cementing fluid with good toughness and high strength to directly replace cement slurry for cementing.[7–9]
Calculation method for the vertical bearing capacity of a riser-surface casing composite pile
Published in Ships and Offshore Structures, 2021
In recent years, the cost of offshore oilfield exploitation has gradually increased in the Bohai Sea. The tasks of some old platforms have become increasingly heavy, and the exploitation difficulty has continued to increase (Wang et al. 2019). The bearing capacity design of some jacket platforms can no longer meet the increasing demands of the exploitation tasks. Furthermore, to improve economic benefits, in addition to the conventional large oil fields, increasingly marginal, low-capacity, and inefficient block oil fields, including small marginal oil fields, need to be developed (Yang 2003; Permata and Hatzignatiou 2011; Carpenter 2014; Zhao et al. 2016). To save development costs, some simple platform structures have been developed. Whether involving a traditional jacket platform or a simple platform, the indispensable part of the platform structure is the oil well. The oil wells of offshore platforms generally include risers and surface casings. The riser is a steel pipe that runs from the offshore drilling platform to the shallow seabed during the drilling process. Its main function is to isolate the well from seawater, form a circulation channel for drilling fluid, and provide structural support for the Christmas tree and blowout preventer. The surface casing is usually used to isolate the well from the shallow surface water layer and the shallow complex bottom layer.
Effect of curing conditions on the mechanical properties of cement class G with the application to wellbore integrity
Published in Australian Journal of Civil Engineering, 2018
Elaheh Arjomand, Terry Bennett
Wellbores provide access to natural resources such as oil and gas and are encased in concentric layers of steel casing and cement sheaths. After drilling the borehole, steel casing is inserted and is held in place and protected by a sheath of cement which is pumped into the annular gaps. Although wellbores are sealed and block any interaction which may occur between formation fluid and geologic strata, the integrity of wellbores might still be compromised (Davies et al. 2014; King and King 2013). At this stage, wellbores may turn into the high-permeability conduits for the formation fluids (Watson and Bachu 2007) which could pose a potential risk to the environment by contaminating groundwater and/or the atmosphere. The cement sheath is responsible for providing zonal isolation and preventing the leakage of formation fluids during the lifetime of a wellbore (Ravi, Bosma, and Gastebled 2002) and therefore the cement sheath should be designed and placed so that it withstands the external conditions imposed upon it, including, in-situ stresses, high internal pressures and high temperature.