Steel slag wastes to fight the climate change

Steel slags are solid by-products generated from the steel-manufacturing industries. They are considered valuable wastes for capturing of carbon dioxide (CO2) directly from the air and industrial sources and storing it permanently in the form of mineral carbonation. In this study, two historic steel slags are presented as sustainable materials for mineral carbonation. The effects of contacting time between CO2 and slags as well as temperature were investigated as two important parameters during mineral carbonation. The amount of carbonation, chemical and physical properties of carbonated samples have been characterised using Calcimeter, Fourier-transform infrared spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM). The results showed that depending on the source and composition of the steel slags, the maximum CO2 sequestration after 4 days at 60 °C is reached as high as 300 kg per tonne for samples. The FT-IR results showed the symmetric stretching of O-C-O bonds at 1400-1500 cm-1, gradually increased with increasing temperature and contacting time, indicating the significant capture of CO2 due to the carbonation process. SEM images confirmed that for both samples after the mineralisation, several carbonate layers were created in the structure of steel slags. The results indicated that CO2 sequestration in steel slag is positively correlated with contacting time and temperature, hence the current study provides the optimal conditions to accelerate the process of carbonation for industrial application. It is estimated that these steel slags alone could carbonate about 150-200 million tonnes of CO2 emissions which is equivalent to one third of annual UK greenhouse gas emissions

Study of the effect of clay particles on low salinity water injection in sandstone reservoirs

The need for optimal recovery of crude oil from sandstone and carbonate reservoirs around the world has never been greater for the petroleum industry. Water-flooding has been applied to the supplement primary depletion process or as a separate secondary recovery method. Low salinity water injection is a relatively new method that involves injecting low salinity brines at high pressure similar to conventional water-flooding techniques, in order to recover crude oil. The effectiveness of low salinity water injection in sandstone reservoirs depends on a number of parameters such as reservoir temperature, pressure, type of clay particle and salinity of injected brine. Clay particles present on reservoir rock surfaces adsorb polar components of oil and modify wettability of sandstone rocks to the oil-wet state, which is accountable for the reduced recovery rates by conventional water-flooding. The extent of wettability alteration caused by three low salinity brines on oil-wet sandstone samples containing varying clay content (15% or 30%) and type of clay (kaolinite/montmorillonite) were analyzed in the laboratory experiment. Contact angles of mica powder and clay mixture (kaolinite/montmorillonite) modified with crude oil were measured before and after injection with three low salinity sodium chloride brines. The effect of temperature was also analyzed for each sample. The results of the experiment indicate that samples with kaolinite clay tend to produce higher contact angles than samples with montmorillonite clay when modified with crude oil. The highest degree or extent of wettability alteration from oil-wet to intermediate-wet state upon injection with low salinity brines was observed for samples injected with brine having salinity concentration of 2000 ppm. The increase in temperature tends to produce contact angles values lying in the higher end of the intermediate-wet range (75°–115°) for samples treated at 50 °C, while their corresponding samples treated at 25 °C produced contact angle values lying in the lower end of intermediate-wet range

Steel slag wastes to fight the climate change

Steel slags are solid by-products generated from the steel-manufacturing industries. They are considered valuable wastes for capturing of carbon dioxide (CO2) directly from the air and industrial sources and storing it permanently in the form of mineral carbonation. In this study, two historic steel slags are presented as sustainable materials for mineral carbonation. The effects of contacting time between CO2 and slags as well as temperature were investigated as two important parameters during mineral carbonation. The amount of carbonation, chemical and physical properties of carbonated samples have been characterised using Calcimeter, Fourier-transform infrared spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM). The results showed that depending on the source and composition of the steel slags, the maximum CO2 sequestration after 4 days at 60 °C is reached as high as 300 kg per tonne for samples. The FT-IR results showed the symmetric stretching of O-C-O bonds at 1400-1500 cm-1, gradually increased with increasing temperature and contacting time, indicating the significant capture of CO2 due to the carbonation process. SEM images confirmed that for both samples after the mineralisation, several carbonate layers were created in the structure of steel slags. The results indicated that CO2 sequestration in steel slag is positively correlated with contacting time and temperature, hence the current study provides the optimal conditions to accelerate the process of carbonation for industrial application. It is estimated that these steel slags alone could carbonate about 150-200 million tonnes of CO2 emissions which is equivalent to one third of annual UK greenhouse gas emissions

Robust and Flexible Hydrocarbon Production Forecasting Considering the Heterogeneity Impact for Hydraulically Fractured Wells

Producing oil and gas from increasingly more difficult reservoirs has become an unavoidable challenge for the petroleum industry because the conventional hydrocarbon resources are no longer able to maintain the production levels corresponding to the global energy demand. As the industrial investments in developing lower permeability reservoirs increase and more advanced technologies, such as horizontal drilling and hydraulic fracturing, gain more attention and applicability, the need for more reliable means of production forecasting also become more noticeable. Production forecasting of hydraulically fractured wells is challenging, particularly for heterogeneous reservoirs, where the rock properties vary dramatically over short distances, significantly affecting the performance of the wells. Despite the recent improvements in well performance prediction, the issue of heterogeneity and its effects on well performance have not been thoroughly addressed by the researchers and many aspects of heterogeneity have yet remained unnoticed. In this paper, a novel empirical approach for production forecasting of multi-fractured horizontal wells is presented in an attempt to effectively include the effect of heterogeneity. This approach is based on the integration of hyperpolic decline curve analysis (DCA) and heterogeneity impact factor (HIF). This newly defined ratio quantifies the heterogeneity impact on the hydraulically fractured well performance and is calculated on the basis of net pressure match interpretation and post-fracture well test analysis. The proposed approach of the decline curve using heterogeneity impact factor (DCH) is validated against data from a southern North Sea field. The results show a maximum of 15% difference between the outcome of the proposed method and the most detailed three-dimensional history-matched model, for a 15 year period of production forecasts. DCH is a novel, fast, and flexible method for making reliable well performance predictions for hydraulically fractured wells and can be used in forecasting undrilled wells and the range of possible outcomes caused by the heterogeneity

Multi-criteria site selection workflow for geological storage of hydrogen in depleted gas fields: A case for the UK

Underground hydrogen storage (UHS) plays a critical role in ensuring the stability and security of the future clean energy supply. However, the efficiency and reliability of UHS technology depend heavily on the careful and criteria-driven selection of suitable storage sites. This study presents a hybrid multi-criteria decision-making framework integrating the Analytical Hierarchy Process (AHP) and Preference Ranking Organisation Method for Enrichment of Evaluations (PROMETHEE) to identify and select the best hydrogen storage sites among depleted gas reservoirs in the UK. To achieve this, a new set of site selection criteria is proposed in light of the technical and economic aspects of UHS, including location, reservoir rock quality and tectonic characteristics, maximum achievable hydrogen well deliverability rate, working gas capacity, cushion gas volume requirement, distance to future potential hydrogen clusters, and access to intermittent renewable energy sources (RESs). The framework is implemented to rank 71 reservoirs based on their potential and suitability for UHS. Firstly, the reservoirs are thoroughly evaluated for each proposed criterion and then the AHP-PROMETHEE technique is employed to prioritise the criteria and rank the storage sites. The study reveals that the total calculated working gas capacity based on single-well plateau withdrawal rates is around 881 TWh across all evaluated reservoirs. The maximum well deliverability rates for hydrogen withdrawal are found to vary considerably among the sites; however, 22 % are estimated to have deliverability rates exceeding 100 sm3/d, and 63 % are located within a distance of 100 km from a major hydrogen cluster. Moreover, 70 % have access to nearby RESs developments, with an estimated cumulative RESs capacity of approximately 181 GW. The results highlight the efficacy of the proposed multi-criteria site selection framework. The top five highest-ranked sites for UHS based on the evaluated criteria are the Cygnus, Hamilton, Saltfleetby, Corvette, and Hatfield Moors gas fields. The insights provided by this study can contribute to informed decision-making, sustainable development, and the overall progress of future UHS projects within the UK and globally