The present article analyzes the technological advancement and innovations related to drilling operations. It covers the review of currently proven and emerging technologies that could mitigate the drilling operational deficiencies and instabilities that could hinder operational performance activities and the economic part of drilling development with great effort to minimize their environmental footprint. Drilling system design and operations are among the major aspects and cost-effective endeavors of the oil and gas industries, which are therefore technology dependent. They are also considered to be among the most expensive operations in the world, as they require huge expenses daily. Drilling success, depending on prevalent conditions, is a function of several general factors. These include the selection of the best technologies and tools, procedural optimization, concrete problem-solving, accurate prediction, and rapid decision-making. Consequently, any sorts of tools or advanced technologies that can improve the time-efficient operational and economic performance of drilling activities are essential and demanded. The paper provides a review of available technologies and developmental innovations based on both company-based and academic research-enabled drilling solutions over the past 5 years in the field of drilling systems and technological design. The paper further highlighted potential technologies that could be tapped in from other industries and could possibly be adopted by pushing the conventional boundaries of drilling operations.

Energy is an essential component for prosperity, economic growth, and development and has become a basic necessity for humans, but at the same time, it has an impact on the environment. Therefore, it is believed that, in the coming future, renewable energy will play an important part in fulfilling the energy demand. In that respect, geothermal energy will be vital as it is a continuous source of energy that is not affected by metrological conditions and can be used in power generation or domestic heating. Many countries around the globe are actively producing energy from geothermal resources. However, the extraction of the heat from the subsurface comes with challenges such as subsurface environment, wellbore instability, corrosion, loss of circulation, and cementing operation. However, one of the most challenging and critical tasks is the zonal isolation of the geothermal well. A packer is a tool that is used for the zonal isolation of a well, and at high pressure and high temperature (HPHT) conditions, which is common for geothermal wells. Most of the components of packers fail, causing well integrity issues. This paper gives a review of the forces acting on packers, testing standards, problems encountered by a packer in the HPHT subsurface environment, and designs to overcome those problems.

Geothermal well integrity has proven to be of high importance, especially because the geothermal life span is expected to be longer than that of conventional oil and gas wells. Recent studies have demonstrated that cement-casing interfacial bonding is a classical well failure in such wells, but field measurements do not correlate with the simulations. We believe that this discrepancy is due to limitations of the simulation itself, which in most cases assumes a free movement of the casing after the interfacial bonding has been exceeded. Since the casing is cemented using a complex hardware package such as centralizer and other cementing components, the free movement of the casing is only possible when no-cement exists behind the casing. This paper proposes a novel experimental method to understand cement strength properties other than the standardized unconfined cement strength (UCS). The novel setup allows the measurement of interfacial bonding strength between cement and casing and the pure cement shear strength. The later becomes an important parameter as the interaction between casing couplings and cement will show. In the past, standard cement bending tests were designed to measure cement shear, but the value obtained from such tests is not relevant for the geothermal in situ casing-cement interaction, and thus the need for a new testing method arose. The new method is capable to mimic the interaction between the casing connection edges and the cement. We believe that the results presented within this paper will help engineers to validate their numerical simulations and to optimize the geothermal well design which will result in the increase of the well integrity for the life of the geothermal well.

Geothermal energy has been used by mankind since ancient times. Given the limited geographical distribution of the most favorable resources, exploration efforts have more recently focused on unconventional geothermal systems targeting greater depths to reach sufficient temperatures. In these systems, geothermal well performance relies on efficient heat transfer between the working fluid, which is pumped from surface, and the underground rock. Most of the wells designed for such environments require that the casing strings used throughout the well construction process be cemented in place. The overall heat transfer around the wellbore may be optimized through accurate selection of cement recipes. This paper presents the application of a three-phase analytical model to estimate the cement thermal properties. The results show that cement recipes can be designed to enhance or minimize heat transfer around wellbore, extending the application of geothermal exploitation.