Benchmarking offshore drilling: methodology and case study

The distinct characteristics of geothermal wells necessitate a unique and specialized approach to well design. This is critical for prolonging well lifespan and tackling the unique operational challenges present in mature geothermal fields, such as the case on a field in the Philippines. To enhance steam production, geothermal wells often intersect faults and complex geological formations, which result to partial to total fluid losses. These losses introduce significant uncertainty in cementing and compromise its quality. Such issues can lead to channeling, the formation of micro-annuli, and cement degradation — all of which undermine well integrity and reduce production efficiency. Furthermore, these cementing challenges, especially in the case of geothermal wells, may result to having trapped fluid in casing-to-casing annulus that can potentially compromise well integrity due to huge temperature swings that the wells encounter over their operating lives. Addressing these integrity concerns in a cost-effective manner is critical to maintaining safe, efficient, and economically viable well operations over time. To overcome these challenges, Welltec partnered with a geothermal operator in the Philippines to rehabilitate eight geothermal production wells affected by casing collapse and parted casing. A traditional workover involving bridge plugs was deemed impractical, as drilling out the plug risked further damage to liners exposed to corrosive, low-pH fluids. There was also a concern that trapped fluids could trigger additional casing failures. Therefore, a more controlled and precise cementing strategy was required to restore casing integrity. This paper introduces a tailored solution that integrates high-temperature Metal Expandable Packer technology and stage cementing collars. Case studies from a geothermal field in the Philippines illustrate how this approach restores well integrity without the need for a dedicated drill-out run. Building on experience from prior deployments, the improved MEP enables long-string tieback and casing relining to depths of approximately 1,300 meters — previously considered unattainable due to casing collapse, which had limited operations to around 700 meters. New well designs using CRA are also being optimized to benefit from such solution and withstand highly acidic environments. These wells require immediate relining, applying insights from earlier CRA wells in the same field. The MEP system eliminates the need to drill out plugs, thereby preventing damage to CRA casing. Integrating MEP technology into both drilling and workover operations offers a robust strategy to resolve integrity issues that typically lead to early well failure. This geothermal-specific technology enhances repeatability, safety, and operational control, ultimately enabling more reliable and extended utilization of geothermal resources.

The transition from fossil energy to clean energy is an ongoing trend. Because geothermal energy is buried beneath oil /gas wells, it is desirable to convert abandoned oil/gas wells to geothermal energy wells. The candidate wells can be dry holes in oil/gas exploration or end-of-life oil/gas wells in depleted oil/gas reservoirs. There is a knowledge gap to fill between the oil/gas wells and geothermal wells in the well conversion engineering, that is, factors affecting the performance of the geothermal wells are not fully understood. The mathematical model developed by Wei and Guo (2023) was used in this work to investigate the factors affecting the temperature of produced water of geothermal energy wells converted from abandoned oil/gas wells. Both vertical and horizontal well options were considered. The result of the field case study using the data for a well in the Songliao Basin of Northeastern China shows that, without pipe insulation, the temperature of the returned water is very close to that of the injected water, regardless of vertical or horizontal wells. With pipe insulation, the temperature of the returned water in the horizontal well is higher than that in the vertical well. The temperature of the returned water declines quickly as the thermal conductivity of pipe insulation increases in the low-thermal conductivity region. The temperature of the returned water in horizontal wells is affected by the horizontal hole section length for heat transfer. But this effect levels off after about 1,000 m of horizontal hole section is reached, meaning that 1,000 m of horizontal hole section is adequate for heat transfer from the geothermal zone to the injected water. This paper provides an analytical method for the technical feasibility assessment of converting abandoned oil/gas wells to geothermal energy wells.

Global climatic warming associated with increased concentrations of `green house' gases, such as CO2, has long been recognized by scientists although not by the general public.It is time to focus public attention on the warming of the atmosphere due to the green house effect and to discuss it with not only experts but also policy makers and government officials with in congressional hearings and meetings. International organizations are currently conducting meeeting on institutional countermeasures for limitation of CO2 emission. The impacts of these limitations of CO2 emmision on energy economics (energy demand and supply, energy market) have to be assessed using an institutional approach.The meeting in Tronto in June 1988 appealed to wealthy nations to cut their CO2 emissions by 20% by the year 2005. This study examines these issues by assessing the impacts of the Tronto meeting's appeal. Its principal findings are as follows.1. CO2 emission level in 2005 in the no-limitation case will be 1. 7 times higher than the goal of the Tronto appeal. CO2 emission levels of OECD countries in 2005 will be 1.5 times higher than the goal of the Tronto appeal; Centrally planned economies will be 1.9 times higher; LDCs will be 2.0 times higher.2. It is important that Centrally planned economies, especialy China and the LDCs participate in the CO2 emission limitation club.3. The CO2 emission limitation meeting of Tronto's goal would result in a drastic change in energy mix which would be followed by an unbalance of energy demand and supply, energy price rises and changes in economy growth.4. The greatest determinant of the level of future CO2 emissions is the degree of future improvement in energy efficiency. But each country has different levels of energy efficiency.Therefore each country has different potential for future improvement in energy efficiency.

Türkiye relies on coal-fired power plants for approximately 18 GW of annual electricity generation, with significantly higher CO2 emissions compared to geothermal power plants. On the other hand, geothermal energy resources, such as Enhanced Geothermal Systems (EGS) and hydrothermal systems, offer low CO2 emissions and baseload power, making them attractive clean energy sources. Radiogenic granitoid, with high heat generation capacity, is a potential and cleaner energy source using EGS. The Anatolian plateau hosts numerous tectonic zones with plutonic rocks containing high concentrations of radioactive elements, such as the Central Anatolian Massif. This study evaluates the power generation capacity of the Hamit granitoid (HG) and presents a thermo-hydraulic-mechanical (THM) model for a closed-loop geothermal well for harnessing heat from this granitoid. A sensitivity analysis based on fluid injection rates and wellbore length emphasizes the importance of fluid resident time for effective heat extraction. Closed-loop systems pose fewer geomechanical risks than fractured systems and can be developed through site selection, system design, and monitoring. Geothermal wellbore casing material must withstand high temperatures, corrosive environments, and should have low thermal conductivity. The HG exhibits the highest heat generation capacity among Anatolian granitoid intrusions and offers potential for sustainable energy development through EGS, thereby reducing CO2 emissions.

Geothermal resources are green and environmentally friendly renewable energy. An accurate evaluation of geothermal resources will help subsequent efficient exploitation. However, to save costs and improve efficiency, core-free drilling and without mud logging are adopted in the actual exploration, which results in an inability to directly obtain the relevant evaluation parameters of a geothermal reservoir for exploration and evaluation. Well logging technology can effectively delineate the geothermal reservoir and determine the location of the major aquifer, while also allowing for the accurate measurement of key reservoir evaluation parameters, such as the shale content, porosity, and well temperature. Moreover, coupled with the calculated logging parameters, a volumetric method can be used to determine the regional geothermal reserves. This research takes the geothermal wells of the Guanghuasi Formation in the Qianjiang sag, Jianghan Basin as an example to conduct the application research. The findings can be of reference for similar geothermal wells in China and facilitate the development of “carbon neutrality.”

Comparative analysis of decision-making methods for integrating cost and CO2 emission – focus on building structural design –

With increasing concerns about global warming, and the cement plants emitting huge CO2, it is necessary to know how the CO2 emits and how much the CO2 emits due to cement manufacture in both direct and indirect ways. A precise method to calculate CO2 emissions including three processes was established in this paper and a case study was provided. From the case of LQDX plant, we can see the amount of CO2 emissions at the right level. The summary of CO2 emissions is consisted by emissions from raw materials, fuels and electricity. The direct CO2 emissions are 0.822 ton CO2 per ton clinker, and the total CO2 emissions are 0.657 ton CO2 per ton cement in this study. Therefore, the way that CO2 emissions due to cement manufacture was pictured and then measured. An approach provides a basic framework to identify various situations in different cement plants in China and other in the rest of the world. The framework would be useful in quantitatively evaluating CO2 emissions for government to know precisely CO2 emissions in cement plants.

Traffic Modeling and Safety Analysis on Motorway Ramps

Geothermal energy is a globally distributed sustainable energy with the advantages of a stable base load energy production with a high capacity factor and zero SOx, CO, and particulates emissions. It can provide a potential solution to the depletion of fossil fuels and air pollution problems. The geothermal district heating and cooling system is one of the most common applications of geothermal energy, and consists of geothermal wells to provide hot water from a fractured geothermal reservoir, a surface energy distribution system for hot water transmission, and heating/cooling facilities to provide water and space heating as well as air conditioning for residential and commercial buildings.;To gain wider recognition for the geothermal district heating and cooling (GDHC) system, the potential to develop such a system was evaluated in the western United States, and in the state of West Virginia. The geothermal resources were categorized into identified hydrothermal resources, undiscovered hydrothermal resources, near hydrothermal enhanced geothermal system (EGS), and deep EGS. Reservoir characteristics of the first three categories were estimated individually, and their thermal potential calculated. A cost model for such a system was developed for technical performance and economic analysis at each geothermally active location. A supply curve for the system was then developed, establishing the quantity and the cost of potential geothermal energy which can be used for the GDHC system.;A West Virginia University (WVU) case study was performed to compare the competiveness of a geothermal energy system to the current steam based system. An Aspen Plus model was created to simulate the year-round campus heating and cooling scenario. Five cases of varying water flow rates and temperatures were simulated to find the lowest levelized cost of heat (LCOH) for the WVU case study. The model was then used to derive a levelized cost of heat as a function of the population density at a constant geothermal gradient. By use of such functions in West Virginia at a census tract level, the most promising census tracts in WV for the development of geothermal district heating and cooling systems were mapped.;This study is unique in that its purpose was to utilize supply analyses for the GDHC systems and determine an appropriate economic assessment of the viability and sustainability of the systems. It was found that the market energy demand, production temperature, and project lifetime have negative effects on the levelized cost, while the drilling cost, discount rate, and capital cost have

Government of India has set an ambitious target of reducing hydrocarbon import. Increasing oil & gas production is one of the measures by which oil & gas import dependency can be reduced. Despite relatively low crude prices globally, substantial E&P activities have been carried out in the country in the last decade, which has witnessed an exponential increase in exploration of oil and gas reserves. Many new fields were discovered during this exploration campaign out of which, few are potential traps containing hydrocarbons. Kutch and Saurashtra Basin off Gujarat coast is one of the exploration fields that involves trap drilling to explore reservoir sands below. Recently for the very first time, in a decade, oil reserves have been discovered in prospective sedimentary basin of Saurashtra. (DGH India Outlook, 2017-18) Drilling in this basin is characterized by slow rate of penetration (ROP), frequent bit trips, drill string failure, and high well cost. The 12 1/4-in section in this offshore block typically drills through very hard, abrasive and thick layers of Basaltic formation (known as Deccan Trap) with unconfined compressive strength (UCS) between 18-42 kpsi. Conventional polycrystalline diamond compact (PDC) bits and roller cone (RC) bits faced extreme cutting structure damage and delivered poor ROPs in this section. In this paper, challenges of drilling approximately 2,200 m of hard and abrasive Deccan Trap in the 12.25-in section is discussed along with a proposed solution of hybrid bit design by combining conical (CDE) and ridged (RDE) diamond elements. Two new hybrid 8-bladed 16-mm bit were specifically designed for this application. The first bit drilled an interval of 952m with an average ROP of 1.9m/hr and the second bit drilled an interval of 960m with an average ROP of 1.83m/hr. Both the bits came out of the hole in good condition, thereby delivering a benchmark performance in drilling this challenging section. The runs resulted in 40% reduction in cost/meter for this section and saved 36 offshore days for the customer.

Traffic congestion is a major problem around the world that results in slower speeds, increased trip time, and a longer queuing of vehicles. The production and use of fuels for vehicles results in emissions of greenhouse gases (GHSs), besides carbon dioxide, which include methane and nitrous oxide. Traffic lights that wirelessly keep track of vehicles could reduce journey time and fuel consumption thereby reducing carbon emissions. In view of the importance of vehicles as an emitter of GHGs, namely CO2, with the growing concern about climate change, this paper aims to explore the emission of CO2 from vehicles at a traffic intersection for the purpose of reducing emission rate. Realizing this reduction, points to the implementation of an Advanced Traffic Management System (ATMS) with Wireless Sensor Networks (WSNs) on the road network of a region will be discussed. With such a technology, a region can experience lower queue lengths at an intersection and therefore lower CO2 emission surrounding the area. The University of Nigeria, Nsukka (UNN) is used as a case study in exploring this phenomenon which over the years has seen a drastic increase on the amount of cars on the campus area. With the assumption that an ATM system with WSNs is deployed on the UNN campus area, the paper looks into the traffic dynamics that makes it possible to evaluate CO2 emission at traffic light intersections to ensure a cleaner environment. Throughout the paper, it will be made clear that with the relevant equation of CO2 emission and the arrival time per vehicle, CO2 emission rate can be evaluated at a traffic intersection depending on the volume of cars at the intersection. With such evaluation, further analysis can be made on ways to actually reduce CO2 emission and techniques for implementation with an ATM system.

<p>The aim of this research is to establish whether container architecture in the residential sector of New Zealand is energy efficient in contrast with traditional houses built by different building materials. This study is part of a discussion on sustainability in prefabricated architecture. The term "container architecture" has not been assessed in depth yet. On the other hand, the concept of prefabrication in architecture is well documented. Despite the large amount of empirical knowledge, little is known about container architecture in the residential sector. A comparative life cycle analysis has been undertaken by emphasising three different approaches: Energy consumption, CO2 emissions and the thermal performance of three conventional building materials (steel, concrete and timber-based structures) in the residential sector of New Zealand. Results from international studies of the Life Cycle Analysis (LCA) method in houses have been mixed. A number of studies suggest the importance of this methodology in order to achieve benefits in the reduction of energy consumption and CO2 emissions. Most of these studies agree that operational energy is the highest driver of both the energy consumed and CO2 emitted. However, some studies disagree with this approach due to the assumption made in the underestimation of the energy used in the transport of raw materials in the construction process of a building. Establishing a comparative life cycle analysis between a container-house, a concrete dwelling and a timber residence may provide further insight in the understanding of the patterns related to the energy consumption and CO2 emissions in the residential sector when container houses are used. Such understanding may be useful in developing more efficient houses. The household data for each project has been calculated and this information has been used to explore the drivers of the energy consumption and CO2 emissions through the lifespan of every example. Three case studies have been selected for this comparative life cycle analysis. Selection criteria are based upon relationships between container-architecture's main features that match with some ideals of the Modern Movement in Architecture: the construction of prefabricated and mass produced elements, modularity and formal simplicity. Emphasis is put on numerical relationships related to shipping steel-boxes, size and form, scale, material properties, density, site location and climatic conditions. The three case studies are: for steel, the Stevens House, which is the first container house constructed in Wellington, for concrete, a single dwelling unit of the Jellicoe Towers, a post-WWII model of Modern Architecture in New Zealand built in the late 1960s and for timber, the Firth House, a wooden-based house designed by Cedric Firth which was inspired by the works of Walter Gropius and Konrad Wachsmann, German figures of the Modern Movement in Architecture. The life cycle energy consumption is given by using two different software packages. The first is known as Gabi, which has a European database. It is useful to calculate the total amount of energy used and the amount of CO2 released into the atmosphere by the different projects through their lifespan. The second program is New Zealand software known as ALF 3 (Annual Loss Factor 3), developed under BRANZ (Building Research Association of New Zealand) which is useful to calculate space heating energy. The outcome of the research shows that the usage of shipping containers in buildings leads to a major consumption of energy (per square metre) and release of CO2 into the atmosphere (per square metre) in comparison with traditional concrete and timber buildings.</p>

Sustainable development of container terminals is based on energy efficiency and reduction in CO2 emissions. This study estimated the energy consumption and CO2 emissions in container terminals according to their layouts. Energy consumption was calculated based on utility data as well as fuel and electricity consumptions for each container-handling equipment in the container terminal. CO2 emissions were estimated using movement modality based on the number of movements of and distance travelled by each container-handling equipment. A case study involving two types of container terminal layouts i.e. parallel and perpendicular layouts, was conducted. The contributions of each container-handling equipment to the energy consumption and CO2 emissions were estimated and evaluated using statistical analysis. The results of the case study indicated that on the CO2 emissions in parallel and perpendicular layouts were relatively similar (within the range of 16–19 kg/TEUs). These results indicate that both parallel and perpendicular layouts are suitable for future ports based on sustainable development. The results can also be used for future planning of operating patterns and layout selection in container terminals.

Iran is one of the largest producers of CO2 in the world. Therefore, in order to lessen its greenhouse gas production, thus complying with the Intended Nationally Determined Contributions (INDCs), it should cut its CO2 emissions by about 4% by 2030, compared to 2010. Hence this paper aims at finding an early solution to this problem. Because the country's electricity sector is responsible for the highest annual CO2 emissions, the paper focuses on two technologies that can effectively reduce CO2 emissions from the electricity sector, namely renewable energy and Combined Heat And Power Plants (CHP) with CO2 capture and storage (CCS). Further it assesses adoption of these technologies and their impact on Iran's annual CO2 emission by 2030, considering two main scenarios: the optimistic scenario (OS) which assumes that the policies of the Sixth Development Plan (SDP) will be fully realized as well as the fair scenario (FS) which believes that SDP policies will be followed to some extent by the end of the program. To this end, twenty six micro-factors, affecting CO2 emissions, have been identified and classified into five different groups. The detected micro factors are then introduced to a Gradient Boosting Decision Tree (GBDT) Algorithm to identify the most important specific microscopic factors in Iran. The final detected micro-factors have finally been included in a Gaussian regression model to predict CO2 emissions in Iran by 2030. The findings suggest that if Iran intends to comply with the INDCs, CHP-CCS technology is a solution that has an early return, compared to renewable technologies.

The contribution of ploughing permanent grassland and leys to emissions of N2O and CO2 is not yet well known. In this paper, the contribution of ploughing permanent grassland and leys, including grassland renovation, to CO2 and N2O emissions and mitigation options are explored. Land use changes in the Netherlands during 1970–2020 are used as a case study. Three grassland management operations are defined: (i) conversion of permanent grassland to arable land and leys; (ii) rotations of leys with arable crops or bulbs; and (iii) grassland renovation. The Introductory Carbon Balance Model (ICBM) is modified to calculate C and N accumulation and release. Model calibration is based on ICBM parameters, soil organic N data and C to N ratios. IPCC emission factors are used to estimate N2O-emissions. The model is validated with data from the Rothamsted Park Grass experiments. Conversion of permanent grassland to arable land, a ley arable rotation of 3 years ley and 3 years arable crops, and a ley bulb rotation of 6 years ley and one year bulbs, result in calculated N2O and CO2 emissions totalling 250, 150 and 30 ton CO2-equivalents ha–1, respectively. Most of this comes from CO2. Emissions are very high directly after ploughing and decrease slowly over a period of more than 50 years. N2O emissions in 3/3 ley arable rotation and 6/1 ley bulb rotation are 2.1 and 11.0 ton CO2-equivalents ha–1 year–1, respectively. From each grassland renovation, N2O emissions amount to 1.8 to 5.5 ton CO2-equivalents ha–1. The calculated total annual emissions caused by ploughing in the Netherlands range from 0.5 to 0.65 Mton CO2-equivalents year–1. Grassland renovation in spring offers realistic opportunities to lower the N2O emissions. Developing appropriate combinations of ley, arable crops and bulbs, will reduce the need for conversion of permanent pasture. It will also decrease the rotational losses, due to a decreased proportion of leys in rotations. Also spatial policies are effective in reducing emissions of CO2 and N2O. Grassland ploughing contributes significantly to N2O and CO2 emissions. The conclusion can be drawn that total N2O emissions are underestimated, because emissions from grassland ploughing are not taken into account. Specific emission factors and the development of mitigation options are required to account for the emissions and to realise a reduction of emissions due to the changes in grassland ploughing.