Monitor Survey Research Articles

Time-lapse 4D full-waveform inversion for ocean-bottom cable seismic data with seawater velocity changes

Time-lapse (4D) full-waveform inversion (FWI) is a valuable technology for high-resolution imaging of reservoir changes caused by hydrocarbon production and CO$_2$ storage. However, it still faces challenges in dealing with non-repeatability issues due to changes in seawater or near-surface velocity between baseline and monitor surveys. Despite recent advances, the ability of 4D FWI to address this problem has rarely been demonstrated. {\color{red}We} investigate the effectiveness of current 4D FWI strategies, including parallel, double-difference, sequential, and common-model strategies, in resolving non-repeatability issues for 4D OBC (ocean-bottom cable) seismic data. Additionally, a three-stage 4D FWI strategy is developed for 4D OBC seismic data, involving the estimation of seawater velocities in the baseline and monitor models, obtaining a good common starting model, and final convergence to obtain subsurface 4D changes. The synthetic data tests conducted with varying levels of seawater velocity changes indicate that among the current strategies tested, the common-model strategy performs the best, and that our new strategy can further enhance the 4D inversion results.

Targeted nullspace shuttling in time-lapse full-waveform inversion

Time-lapse inversion plays an important role in monitoring applications. Uncertainties in seismic inversion mean that there are many time-lapse changes in subsurface properties consistent with a given time-lapse data set and monitor survey, including changes that are implausible given our prior knowledge. Many existing time-lapse inversion methodologies that aim to minimize spurious differences while preserving real changes are equivalent to undirected navigation about the inversion nullspace. We develop an approach that explicitly navigates the inversion nullspace to find the data-consistent time-lapse model that best satisfies our prior knowledge. In synthetic examples, this approach demonstrates a significant capacity to mitigate the effects of nonreproducible noise and changing acquisition and to identify when time-lapse differences fall below the confidence threshold described by nullspace shuttling.

Unraveling gender differences in entrepreneurial exits: The role of human capital and family situation during an unprecedented crisis

This study applies a gender role perspective to delve into disparities in entrepreneurial exit decisions during unprecedented crises such as the COVID-19 pandemic. The paper examines how human capital and family dynamics—encompassing family income and size—interact with evolving social roles and responsibilities. Using multinomial estimation techniques and Global Entrepreneurship Monitor survey data from Chile, our findings reveal that women entrepreneurs display a higher likelihood of business exits compared to their male counterparts. Further analysis with moderating variables shows that the gender coefficient is not significant and unveils a non-linear pattern tied to educational backgrounds. Specifically, women with elementary education are prone to discontinuing businesses due to the COVID-19 crisis, with a similar—though weaker—tendency observed among women with tertiary education. Women with medium education levels do not significantly differ from men in terms of business closures due to COVID-19. Additionally, family size disproportionately affects women, amplifying the likelihood of business exits during the COVID-19 crisis compared to men. The paper offers actionable insights for researchers and policymakers, emphasizing the pressing need to augment women's entrepreneurial resilience in the face of unforeseen crises.

The Influence of Service Quality and Customer Satisfaction on Customer Loyalty of BCA Mobile in Bandar Lampung

PT. Bank Central Asia, Tbk, founded in 1957, is one of the largest private banks in Indonesia today with an asset value of 1,408 trillion rupiah with a net profit of 48.6 trillion rupiah. The results of the Bank Service Excellence Monitor (BSEM) survey conducted by Marketing Research Indonesia (MRI) in the 2020-2021 edition produced data that BCA Mobile was ranked second and the 2023-2024 edition was ranked fifth in the 10 best mobile banking performances in Indonesia. The problem in this research is that there has been a decline in BCA Mobile's performance followed by many complaints about the use of the BCA Mobile application, which has become a trending topic on the X social media platform (Twitter). BCA Mobile must attention to this so that customers do not think about looking for alternatives to other mobile banking. The aim of this research is to test whether service quality and customer satisfaction have an influence on BCA Mobile customer loyalty in Bandar Lampung City. This research uses a survey method by distributing questionnaires to 90 respondents via Google Form. The analytical method used is simple regression using the partial test (t test) and Sobel test with the SPSS 25 application. The results of the research show that the service quality variable and customer satisfaction variable have an influence on the BCA Mobile customer loyalty variable in Bandar Lampung City.

Tuning effect in time-lapse seismic inversion for CO2 plume monitoring at Sleipner field

Over 20 million tons of CO2‌ have been injected into the sandy Utsira formation of the Sleipner field in the North Sea basin. The thin layering of sands, CO2-saturated sands, and intra-formation thin shales cause interference effects in the seismic response of the monitor surveys. Initial analysis of the amplitude change suggests over 60 % change in the relative acoustic impedance of the reservoir between the 1996 and 2010 surveys. This study follows a multi-stage inversion scheme applied to time-lapse seismic monitoring of the Sleipner field. At each stage, the errors and uncertainties caused by noise and tuning are deeply analyzed. Time-shift estimation from seismic data shows spurious features caused by tuning, specifically using the window-based methods. The time-strain inversion builds a low-frequency initial model for the subsequent model-based inversion but is contaminated by remnants of noise and interference. The synthetic wedge modelling and analysis provides the origins and severity of the tuning error in time-shift and time-strain estimations at the Sleipner field. The model-based inversion removes noise and injects high-frequency components into the results, improving the outcome of time-strain inversion. However, it fails to fully eliminate the tuning imprints and leaves strong traces of error on the results. Afterward, the time-lapse Bayesian seismic inversion slightly adjusts the outcome and shows how deep the influence of interference effect on the time-lapse inversion is. In addition, the complementary discussion on rock physical models in estimating the saturation changes highlights how the tuning error can lead to flawed quantitative interpretation.

Testing the cultural-invariance hypothesis: A global analysis of the relationship between scientific knowledge and attitudes to science.

A substantial body of research has demonstrated that science knowledge is correlated with attitudes towards science, with most studies finding a positive relationship between the two constructs; people who are more knowledgeable about science tend to be more positive about it. However, this evidence base has been almost exclusively confined to high and middle-income democracies, with poorer and less developed nations excluded from consideration. In this study, we conduct the first global investigation of the science knowledge-attitude relationship, using the 2018 Wellcome Global Monitor survey. Our results show a positive knowledge-attitude correlation in all but one of the 144 countries investigated. This robust cross-national relationship is consistent across both science literacy and self-assessed measures of science knowledge.

Entrepreneurship among Social Workers: Implications for the Sustainable Development Goals

The study’s objective is to analyze the entrepreneurial intentions of social workers and their impact on the SDGs. Furthermore, it seeks to explore social workers’ perceptions and attitudes towards entrepreneurship. Thus, this research aims to answer the following research questions: How do entrepreneurial intentions among social workers influence their contribution to achieving the Sustainable Development Goals (SDGs), and what are the implications of these intentions for social work practices and policies within the framework of sustainable development? Based on a quantitative approach, this study leverages microdata from the 2018 Global Entrepreneurship Monitor (GEM) survey. The dataset includes responses from 4545 social workers across 30 high-income countries. The study employs logistic regression analysis as the primary statistical method to delve into the determinants of entrepreneurial intentions among social workers within this diverse international sample. Key findings indicate that the aspiration to establish a future business is a significant factor, underscoring the importance of entrepreneurial intention in this context. Additionally, social workers in the private sector exhibit a greater predisposition to entrepreneurship compared to their public sector counterparts. The study’s implications for the SDGs are substantial, as promoting entrepreneurship among social workers can contribute to economic growth, poverty reduction, and reduced inequalities (SDGs 1, 8, and 10). It also emphasizes the importance of access to entrepreneurial education, sustainable job creation (SDG 4 and 8), and the development of partnerships among academic institutions, social assistance organizations, and entrepreneurial entities (SDG 17). Furthermore, the research highlights the significance of gender equality and access to entrepreneurial resources (SDGs 5 and 9) in fostering entrepreneurship among social workers.

Mental health in selected MENA countries during COVID-19: an empirical investigation

PurposeThe outbreak of COVID-19 not only had serious negative impacts on the world economy but also on the global mental health because of the psychological disorders associated with the spread of the pandemic, the increased degree of uncertainty and the unprecedented measures taken by different countries to face the pandemic’s spread. This paper analyses the mental health well-being of individuals in selected MENA countries (Jordan, Morocco, Tunisia and Egypt) during the pandemic.Design/methodology/approachThe study employs a pooled OLS model using the Economic Research Forum (ERF) COVID-19 MENA Monitor Survey panel dataset collected during 2020 and 2021.FindingsThe findings show that there is no association between the mental health of individuals in the selected countries and their age, gender, family size, marital status, receipt of social support and participation in care work. Mental health improved at higher levels of education, being employed, being a rural area resident and living in Morocco or Tunisia compared to living in Jordan while it worsened as income declined, food insecurity and anxiety about being infected with Covid-19 increased, being a resident in camps, and during waves 4 and 5. Based on these results, it is recommended that suitable financial, physical and human resources should be directed towards the provision of mental health care services in the region. Also, mental health care services should be accessible to different population groups, with a special focus towards the most vulnerable since they are more prone to mental illnesses, especially during health crises and economic shocks. This should be accompanied by increasing awareness about the provided services and reducing stigma against mental illnesses. Furthermore, introduction of policies targeted towards reducing food insecurity and income instability can play a key role in enhancing mental well-being.Originality/valueAlthough few papers have previously investigated the impact of COVID-19 on mental health in MENA countries, most of them have focused on a country-level analysis and adopted a gender perspective. Hence, this paper aims at exploring the association between mental health well-being and socio-economic factors in selected MENA countries during the pandemic.

Entrepreneurial Intentions in the Caribbean: Antecedents and Variations

Increasingly, researchers and policy makers across the globe explore the transformative role of entrepreneurship in the development process. What remains relatively under interrogated in this process is the issue of entrepreneurial intentions within the Caribbean region. Where entrepreneurial intentions play a pivotal role in future entrepreneurial activity, this area of research can provide useful insights for development policy and practice. Considering the above, three main objectives guide this paper. Firstly, we comparatively examine the entrepreneurial intentions drawn from adult populations across Barbados, Jamaica and Trinidad and Tobago. Secondly, we assess the relative importance of entrepreneurial skills, knowledge, and opportunity to entrepreneurial intentions. Thirdly, we also explore for possible socio[1]demographic variations (specifically based on sex, age, level of educational attainment, and type of current profession or career) in the levels of entrepreneurial intentions. To do this, we utilize available raw data from the Global Entrepreneurship Monitor (GEM) survey for the Caribbean countries. We use this data set to test for the relative significance of key antecedent variables for understanding entrepreneurial intentions. Point to variability in the relationship between attitudinal factors, socio-demographic backgrounds, and entrepreneurial intentions between countries in the study. Implications for a more contextualized theorizations of entrepreneurial intentions are discussed.

Time‐lapse applications of the Marchenko method on the Troll field

AbstractThe data‐driven Marchenko method is able to redatum wavefields to arbitrary locations in the subsurface, and can, therefore, be used to isolate zones of specific interest. This creates a new reflection response of the target zone without interference from over‐ or underburden reflectors. Consequently, the method is well suited to obtain a clear response of a subsurface reservoir, which can be advantageous in time‐lapse studies. The isolated responses of a baseline and monitor survey can be more effectively compared; hence, the retrieval of time‐lapse characteristics is improved. This research aims to apply Marchenko‐based isolation to a time‐lapse marine data set of the Troll field in Norway in order to acquire an unobstructed image of the primary reflections and retrieve small time‐lapse traveltime difference in the reservoir. It is found that the method not only isolates the primary reflections but can also estimate internal multiples outside the recording time. Both the primaries and the multiples can then be utilized to find time‐lapse traveltime differences. More accurate ways of time‐lapse monitoring will allow for a better understanding of dynamic processes in the subsurface, such as observing saturation and pressure changes in a reservoir or monitoring underground storage of hydrogen and CO2.

Institutions and macroeconomic indicators: entrepreneurial activities across the world

PurposeEntrepreneurial activity is a phenomenon that increases the economic growth of countries and improves their social welfare. The economic development levels of countries have significant effects on these entrepreneurial activities. This research examines which institutional and macroeconomic variables explain early-stage entrepreneurship activities in developed and developing economies.Design/methodology/approachThe authors conducted panel data analysis on the data from the Global Entrepreneurship Monitor (GEM) and International Monetary Fund (IMF) surveys covering the years 2009–2018.FindingsFirst, the authors' results reveal that cognitive, normative and regulatory institutions and macroeconomic factors affect early-stage entrepreneurial activity in developed and developing countries differently. Second, the authors' findings indicate that cognitive, normative and regulatory institutions affect early-stage entrepreneurship more positively in developed than developing countries. Finally, the authors' results report that macroeconomic factors are more effective in early-stage entrepreneurial activity in developing countries than in developed countries.Originality/valueThis study provides a better understanding of the components that help explain the differences in entrepreneurship between developed and developing countries regarding institutions and macroeconomic factors. In this way, it contributes to developing entrepreneurship literature with the theoretical achievements of combining institutional theory and macroeconomic indicators with entrepreneurship literature.

Born Globals and Born Sustainables: Motives of Accumulating Wealth and of Making a Difference in the World

Abstract Background/Purpose This study investigates the distinct entrepreneurial motivations driving export activities and sustainability pursuits in Slovenian businesses, with a particular focus on differences between newborns and mature enterprises. The study proposes that entrepreneurs who prioritize wealth accumulation are more likely to engage in export activities, particularly those running startups, under the pressures of global trade. Conversely, in light of the shifting cultural values towards sustainability, it is hypothesized that entrepreneurs who are committed to making a difference in the world will be more inclined towards sustainability engagement, a tendency that may be more pronounced in startups. Methods To test these hypotheses, linear regression modelling, using data collected from the Global Entrepreneurship Monitor survey of businesses in Slovenia was employed. Results Newborns, in comparison to mature businesses, are more engaged in both exporting and sustainability pursuits. Interestingly, the motives behind these activities differ significantly. Exporting is primarily driven by the pursuit of wealth accumulation, while sustainability engagement is motivated by the desire to make a positive difference in the world. Conclusion These findings provide valuable insights into the unique characteristics of internationalization and sustainability pursuits in startups versus mature businesses. They highlight the role of distinct entrepreneurial motivations in shaping business practices, contributing to the literature on entrepreneurship and business sustainability.

Reproductive, maternal, newborn, and child health intervention coverage in 70 low-income and middle-income countries, 2000–30: trends, projections, and inequities

Monitoring the progress in reproductive, maternal, newborn, and child health (RMNCH) using the composite coverage index (CCI) is crucial to evaluate the advancement of low-income and middle-income countries (LMICs) towards the attainment of Sustainable Development Goal target 3. We present current benchmarking for 70 LMICs, forecasting to 2030, and an analysis of inequities within and across countries. In this cross-sectional secondary data analysis, we extracted 291 data points from the WHO Equity Monitor, and Demographic and Health Survey Statcompiler for 70 LMICs. We selected countries on the basis of whether they belonged to LMICs, had complete information about the predictors between 2000 and 2030, and had at least one data point related to CCI. CCI was calculated on the basis of eight types of RMNCH interventions in four domains, comprising family planning, antenatal care, immunisations, and management of childhood illnesses. This study examined CCI as the main outcome variable. Bayesian hierarchical models were used to estimate trends and projections of the CCI at regional and national levels, as well as the area of residence, educational level, and wealth quintile. Despite progress, only 18 countries are projected to reach the 80% CCI target by 2030. Regionally, CCI is projected to increase in all regions of Asia (in southern Asia from 51·8% in 2000 to 89·2% in 2030; in southeastern Asia from 58·8% to 84·4%; in central Asia from 70·3% to 87·0%; in eastern Asia from 76·8% to 82·1%; and in western Asia from 56·5% to 72·1%), Africa (in sub-Saharan Africa from 46·3% in 2000 to 72·2% in 2030 and in northern Africa from 55·0% to 81·7%), and Latin America and the Caribbean (from 67·0% in 2000 to 83·4% in 2030). By contrast, southern Europe is predicted to experience a decline in CCI over the same period (70·1% in 2000 to 55·2% in 2030). Across LMICs, CCIs are higher in urban areas, in populations in which women have higher education levels, and in populations with a high income. Governments of countries where the universal target of 80% CCI has not yet been reached must develop evidence-based policies aimed at enhancing RMNCH coverage. Additionally, they should focus on reducing the extent of existing inequalities within their populations to drive progress in RMNCH. Hitotsubashi University and Japan Society for the Promotion of Science.

Data Assimilation of Production and Multiple 4D Seismic Acquisitions in a Deepwater Field Using Ensemble Smoother with Multiple Data Assimilation

Summary In recent years, time-lapse (4D) seismic (4DS) data have been widely used for reservoir monitoring to provide relevant information on dynamic changes occurring during production. In complex reservoirs, multiple seismic monitor surveys are usually available. Updating reservoir models with these data can be very beneficial to improve the field’s management. In the quantitative integration of 4DS data into the data assimilation (DA) process, it is crucial to define how to deal with more than one seismic monitor. In this work, we continue a series of investigations about seismic DA procedures and expand on them by analyzing ways to assimilate more than one seismic monitor. More specifically, we evaluate different ways of using production data and two monitor surveys (M3 and M5) to calibrate the dynamic models of a real Brazilian reservoir using the ensemble smoother with multiple data assimilation (ES-MDA) method. We performed the following experiments: (1) sequential assimilation of M3 and M5 with parts of well history divided according to the seismic acquisition dates; (2) assimilation of M3 with the entire well history and subsequent assimilation of M5; (3) assimilation of well and M3 data; and (4) assimilation of well and M5 data. For comparison purposes, we also assimilated only well data. From the results, we observed that well and 4DS data misfits were reduced when assimilating both monitors, compared to the cases where only a single monitor (any of them) was used with production data. This conclusion is also true in the comparison with results obtained when only assimilating well data. This indicates that both seismic monitors are important data to be quantitatively considered in DA. In this particular field, using a previous DA run to solely assimilate the newly available monitor (Case 2) delivered better models and long-term forecasts. Therefore, this would be our recommendation. This study highlights the importance of several 4DS acquisitions for reservoir monitoring and management and shows the challenges of their application in seismic DA for better life cycle field applications.

Age, period and cohort effects on time trends in monthly cannabis use in adult population: 1996-2019.

With changes in norms related to cannabis use and in the regulation of cannabis, understanding trends in cannabis use is important, especially differentiating between trends that affect cohorts of all ages similarly, versus trends that disproportionately affect a younger generation. The present study examined the age-period-cohort (APC) effects on monthly cannabis use among adults in Ontario, Canada over a 24-year period. Data were utilised from the Centre for Addiction and Mental Health Monitor Survey, an annual repeated cross-sectional survey of adults 18 years of age and older. The present analyses focused on the 1996 to 2019 surveys, which employed a regionally stratified sampling design using computer-assisted telephone interviews (N = 60,171). Monthly use of cannabis stratified by sex were examined. There was about a five-fold increase in monthly cannabis use from 1996 (3.1%) to 2019 (16.6%). The youngest adults use cannabis monthly more, but the patterns of monthly cannabis use appeared to be increasing among older adults. Adults born in the 1950s had higher prevalence of cannabis use (1.25 times more likely to use) compared to those born in 1964, with strongest period effect in 2019. The subgroup analysis of monthly cannabis use by sex showed little variation in APC effects. There is a change in patterns of cannabis use among older adults and inclusion of birth cohort dimension improves the explanation of cannabis use trends. Adults in the 1950s birth cohort and increases in the normalisation of cannabis use could also be the key to explaining increasing monthly cannabis use.

Exploring the correlates of mental healthcare approaches and employment status among persons with depression and anxiety: A secondary data analysis of a global survey

Anxiety and depression are highly prevalent among working age population, and these conditions have been associated with employment disadvantages. Global understanding of correlates of employment status of persons living with anxiety and depression is necessary to develop and implement policies and interventions to promote better employment outcomes. We aimed to investigate the association between sociodemographic factors, mental healthcare approaches and employment status among persons who experience anxiety and depression. We used data from the 2020 Wellcome Global Monitor survey to explore the correlates of employment status among persons with Depression and Anxiety globally. Multivariable logistic regression analysis and Chi square test were conducted to evaluate the relationships between socio-demographic factors, mental healthcare approach such as self-management, professional care, religious and social support on employment status of people with anxiety and depression. Employment status significantly varied by socio-demographic factors, per capita income of countries, and the type of mental health care approach they used to alleviate anxiety and depression. Older participants, those with college degrees, those who talked to mental health professionals, those who improved on their healthy lifestyle behaviors, those who made a change to their work situation, spent time in nature or outdoors when anxious/ depressed were more likely to be employed as compared to those who did not use approaches. Our findings highlight important connections between mental healthcare and employment, prioritizing these connections in policies and intervention can help curb the economic and personal burden of anxiety and depression.

Integrating 4D Data Into Dynamic Model Improves Johan Sverdrup Field Development

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 209541, “Integration of Johan Sverdrup PRM 4D Data Into the Dynamic Model,” by Monica A. Calvert, Yuri Tsaplin, and Hans P. Hansen, TotalEnergies. The paper has not been peer reviewed. _ The Johan Sverdrup field permanent reservoir monitoring (PRM) system now has recorded two surveys documenting the progression of the waterflood since production and injection began in October 2019, revealing a clear 4D signal linked to the increase in water saturation. The 4D signals have been used to help guide updates within the reservoir model, providing a better understanding of how the field development is progressing. Field Background and PRM System The giant Johan Sverdrup oil field was discovered in 2010 in the North Sea approximately 150 km west of Stavanger. The field is laterally extensive, covering 200 km2 and consisting primarily of Upper Jurassic intra-Draupne sandstone and Upper Triassic-Lower Jurassic Statfjord sandstones in a low relief structure. The reservoir is characterized by excellent porosity and permeability, with drillstem tests showing permeabilities of up to 70 darcies with good communication over long distances and across faults. The oil is undersaturated with a low gas/oil ratio and is normally pressured, with slight depletion from a regional drawdown. Reservoir thickness varies across the field, with the intra-Draupne sandstone ranging from 5 to 40 m. The primary drainage strategy includes initial waterflooding to be supplemented by water-alternating-gas injection at the end of the oil-production plateau. The full field development consists of 64 wells, both platform and subsea. Producers are placed on the structural highs with water injectors placed on the flanks below the initial oil/water contact (OWC). Because of full voidage replacement by water injection, reservoir pressure is expected to stay fairly constant during field life. Johan Sverdrup is the first oil field to have a PRM system installed before production startup. The PRM system is a key component of the reservoir-monitoring and data-acquisition plan and was installed in two stages in 2019 and 2020 (Fig. 1). Yearly monitor surveys are planned to monitor waterflood development. The first seismic acquisition in 2019, referred to as PRM0, covered the initial first stage of installation on the northern part of the field. Stage two of the installation was completed in 2020, and two monitor surveys have since been acquired, covering the entire field, in 2020 (PRM1) and 2021 (PRM2). Feasibility studies show that a 4D response would be detectable within the reservoir. The increase in water saturation caused by water injection and upward movement of the OWC yields an increase in acoustic impedance, or hardening, in the reservoir. For the 4D analysis, the main seismic surfaces used were the Top Aasgard formation, the Top Viking group (which contains the Draupne formation), and the Intra Upper Triassic Unconformity (IUTU). The acoustic impedance increase measured in the 4D seismic data is compared with water-saturation changes within the reservoir model. Differences between the two can highlight areas within the reservoir model that require updating.

4D Seismic Least Square Migration in Carbonates: A Case of Successful Matching

4D seismic surveys are now routinely used to monitor hydrocarbon reservoirs. Because seismic reflections are sensitive to formation stress and fluid content, repeated seismic surveys are able to detect pressure changes and fluid exchanges that occur during field production. These measurements can help to optimise recovery strategy and identify areas where hydrocarbons have been bypassed. In practice, the seismic signal associated with such changes may be negligible, especially in heterogeneous carbonate reservoirs. However, by applying a 4D seismic co-processing workflow, we were able to detect and quantify a 4D signal even with suboptimal repeated acquisition geometry. Seismic inversion helped to overcome noise, multiple contamination, and differences in dynamic amplitude range between baseline and monitor seismic surveys. Matching the 4D seismic signal to changes in reservoir production characteristics aided in the investigation of the mechanism underlying the observed 4D signal. Detectability of 4D signals was found to be primarily related to changes in reservoir pressure and fluid saturation, which increased from 2010 to 2020 the time-lapse between the base and monitor survey.

Cannabis legalization and cannabis use, daily cannabis use and cannabis-related problems among adults in Ontario, Canada (2001–2019)

BackgroundIn the context of cannabis legalization in Canada, we examined the effects on cannabis patterns of consumption, including cannabis use, daily cannabis use and cannabis-related problems. In addition, we examined differential effects of cannabis legalization by age and sex. MethodsA pre-post design was operationalized by combining 19 iterations of the Centre for Addiction and Mental Health (CAMH) Monitor Surveys (N = 52,260; 2001–2019): repeated, population-based, cross-sectional surveys of adults in Ontario. Participants provided self-reports of cannabis use (past 12 months), daily cannabis use (past 12 months) and cannabis-related problems though telephone interviews. The effects of cannabis legalization on cannabis patterns of consumption were examined using logistic regression analyses, with testing of two-way interactions to determine differential effects by age and sex. ResultsCannabis use prevalence increased from 11 % to 26 % (p < 0.0001), daily cannabis use prevalence increased from 1 % to 6 % (p < 0.0001) and cannabis-related problems prevalence increased from 6 % to 14 % (p < 0.0001) between 2001 and 2019. Cannabis legalization was associated with an increased likelihood of cannabis use (OR, 95 % CI: 1.62, 1.40–1.86), daily cannabis use (1.59, 1.21–2.07) and cannabis-related problems (1.53, 1.20–1.95). For cannabis-related problems, a significant two-way interaction was observed between cannabis legalization and age (p = 0.0001), suggesting differential effects among adults ≥55 years. ConclusionsCannabis legalization was associated with an increased likelihood of cannabis use, daily cannabis use and cannabis-related problems. Given increases in these cannabis patterns of consumption, broader dissemination and uptake of targeted prevention tools is indicated.

Bayesian inversion of 4D seismic data to pressure and saturation changes: Application to a west of Shetlands field

AbstractA Bayesian inversion methodology is proposed that inverts angle‐stacked 4D seismic maps to changes in pressure, water saturation and gas saturation. The inversion method is applied to data from a siliciclastic reservoir in the west of Shetlands, UK continental shelf. We present inversion results for three seismic monitor surveys and demonstrate the added value of pressure‐saturation inversion by providing insights into reservoir connectivity and fluid dynamics across 14 years of reservoir production. In these surveys, 4D seismic signals related to waterflood, pressure increase and depletion, and gas exsolution are evident and overlap each other in many regions. To regularize this ill‐posed inversion problem, we propose a Bayesian formulation that incorporates spatially variant prior information derived from a history‐matched reservoir simulation model and well pressure measurements. The benefit of incorporating these multi‐disciplinary data as prior information is demonstrated by comparing to inversion results using a spatially invariant prior. We show that the method takes advantage of the multi‐disciplinary prior information to make more precise inferences where the seismic data are most uncertain. This leads to more realistic spatial distributions for the pressure and water‐saturation inversion results. The non‐uniqueness in this non‐linear inversion is studied by analysing uncertainty estimates produced by stochastic sampling of the Bayesian posterior distribution. Posterior standard deviations are observed to be related to the sensitivity of the seismic amplitudes to the changes in each dynamic property as well as the degree of overlap between changes in different dynamic properties. Estimated pressure increases have a posterior standard deviation of approximately 1 MPa, whereas posterior standard deviations for pressure decrease are on average 4 MPa, with higher values applicable to regions of gas exsolution. The posterior standard deviation for estimates of gas saturation change is 0.07 for moderate, visible saturation signals, but 0.005 for low‐to‐zero gas saturation change. The posterior standard deviation for estimated water saturation change is mainly influenced by overlapping changes in pressure and gas saturation. When water changes dominate the 4D seismic signal, posterior standard deviations are on average 0.05. These values rise to 0.25 in areas where the water change is obscured by pressure or gas‐saturation changes.