Unconventional Reservoir Characterization and Formation Evaluation: A Case Study of a Tight Sandstone Reservoir in West Africa

Unconventional reservoirs, including gas shales and tight gas sands, have gained prominence in the energy sector due to technological advancements and escalating energy demands. The oil industry is eagerly refining techniques to decipher these reservoirs, aiming to reduce data collection costs and uncertainties in reserve estimations. Characteristically, tight reservoirs exhibit low matrix porosity and ultra-low permeability, necessitating artificial stimulation for enhanced production. The efficacy of the stimulation hinges on the organic material distribution, the rock’s mechanical attributes, and the prevailing stress field. Comprehensive petrophysical analysis, integrating standard and specialized logs, core analyses, and dynamic data, is pivotal for a nuanced understanding of these reservoirs. This ensures a reduction in prediction uncertainties, with parameters like shale volume, porosity, and permeability being vital. This article delves into an intricate petrophysical evaluation of the Nene field, a West African unconventional reservoir. It underscores the geological intricacies of the field, the pivotal role of data acquisition, and introduces avant-garde methodologies for depth matching, rock typing, and the estimation of permeability. This research highlights the significance of unconventional reservoir exploration in today’s energy milieu, offering a granular understanding of the Nene field’s geological challenges and proffering a blueprint for analogous future endeavours in unconventional reservoirs

Linearly scaling direct method for accurately inverting sparse banded matrices

In many problems in Computational Physics and Chemistry, one finds a special kind of sparse matrices, termed "banded matrices". These matrices, which are defined as having non-zero entries only within a given distance from the main diagonal, need often to be inverted in order to solve the associated linear system of equations. In this work, we introduce a new O(n) algorithm for solving such a system, being n X n the size of the matrix. We produce the analytical recursive expressions that allow to directly obtain the solution, as well as the pseudocode for its computer implementation. Moreover, we review the different options for possibly parallelizing the method, we describe the extension to deal with matrices that are banded plus a small number of non-zero entries outside the band, and we use the same ideas to produce a method for obtaining the full inverse matrix. Finally, we show that the New Algorithm is competitive, both in accuracy and in numerical efficiency, when compared to a standard method based in Gaussian elimination. We do this using sets of large random banded matrices, as well as the ones that appear when one tries to solve the 1D Poisson equation by finite differences.Comment: 24 pages, 5 figures, submitted to J. Comp. Phy

Adaptive multi-polling scheduler for QoS support of video transmission in IEEE 802.11e WLANs

The 802.11E Task Group has been established to enhance quality of service (QoS) provision for time-bounded services in the current IEEE 802.11 medium access control protocol. The QoS is introduced throughout hybrid coordination function controlled channel access (HCCA) for the rigorous QoS provision. In HCCA, the station is allocated a fixed transmission opportunity (TXOP) based on its TSPEC parameters so that it is efficient for constant bit rate streams. However, as the profile of variable bit rate traffics is inconstant, they are liable to experience a higher delay especially in bursty traffic case. In this paper, we present a dynamic TXOP assignment algorithm called adaptive multi-polling TXOP scheduling algorithm (AMTXOP) for supporting the video traffics transmission over IEEE 802.11e wireless networks. This scheme invests a piggybacked information about the size of the subsequent video frames of the uplink streams to assist the hybrid coordinator accurately assign the TXOP according to actual change in the traffic profile. The proposed scheduler is powered by integrating multi-polling scheme to further reduce the delay and polling overhead. Extensive simulation experiments have been carried out to show the efficiency of the AMTXOP over the existing schemes in terms of the packet delay and the channel utilization

LoRa and Rotating Polarization Wave: Physical Layer Principles and Performance Evaluation

Link reliability and enhanced coverage are the primitive concerns of Low-Power Wide-Area Networks (LPWANs) for suitability to critical Internet of Things (IoT) applications. Reliability is limited by the destructive multipath propagation, data rate and sensitivity, that ultimately limits the coverage range. LoRa by far is the predominant LPWAN operating on unlicensed spectrum. Despite its robust Chirp Spread Spectrum (CSS) modulation, there is a severe degradation in its error performance particularly in hostile propagation environments, and an excessive reduction in coverage. Rotating Polarization Wave (RPW) is a potential LPWAN recently emerged to achieve a highly reliable IoT and Machine-to-Machine (M2M) communication. This is the first paper to provide comprehensive error performance comparison between LoRa and RPW. Okumura-Hata model is used for median path loss calculation. Shadowing and fast fading margins of RPW and LoRa are estimated. Effective gain of RPW is computed from error performance. Results have shown that LoRa offers a sensitivity of 23 dB higher than RPW under AWGN conditions. However, under fading conditions, RPW exhibits a sensitivity of 15 dB higher than LoRa. At a reference distance of 100 m, the maximum received signal strength of RPW is −39 dBm, which is 29 dB above LoRa. The maximum coverage distance attained by RPW is 15 km, which is 1.5 times of LoRa

Impact of the development of an endoscopic eradication program for Barrett's esophagus with high grade dysplasia or early adenocarcinoma on the frequency of surgery

Background and aims  The impact of the advent of an institutional endoscopic eradication therapy (EET) program on surgical practice for Barrett's esophagus (BE)-associated high grade dysplasia (HGD) or suspected T1a esophageal adenocarcinoma (EAC) is unknown. The aims of this study are to evaluate the different endoscopic modalities used during development of our EET program and factors associated with the use of EET or surgery for these patients after its development. Methods  Patients who underwent primary endoscopic or surgical treatment for BE-HGD or early EAC at our hospital between January 1992 and December 2014 were retrospectively identified. They were categorized by their initial modality of treatment during the first year, and the impact over time for choice of therapy was assessed by multivariable logistic regression. Results  We identified 386 patients and 80 patients who underwent EET and surgery, respectively. EET included single modality therapy in 254 (66 %) patients and multimodal therapy in 132 (34 %) patients. Multivariable logistic regression showed that, for each subsequent study year, EET was more likely to be performed in patients who were older ( P  = 0.0009), with shorter BE lengths ( P  < 0.0001), and with a pretreatment diagnosis of HGD ( P  = 0.0054) compared to surgical patients. The diagnosis of EAC did not increase the utilization of EET compared to surgery as time progressed ( P  = 0.8165). Conclusion  The introduction of an EET program at our hospital increased the odds of utilizing EET versus surgery over time for initial treatment of patients who were older, had shorter BE lengths or the diagnosis of BE-HGD, but not in patients with EAC

Causes and risk factors for common mental illnesses : the beliefs of paediatric hospital staff in the United Arab Emirates

Background Children and adolescents with chronic physical health conditions are vulnerable to poor mental health outcomes. The measurement of mental health literacy of health professionals working with such populations is important because of their role in promoting early and appropriate help-seeking. This study sought to determine the beliefs regarding the causes of and risks factors for three types of mental illnesses amongst health professionals in United Arab Emirates. Method A culturally validated mental health literacy survey presenting three vignettes of fictional characters meeting diagnostic criteria for posttraumatic stress disorder, depression with suicidal thoughts and psychosis was distributed. The survey measured health care professionals’ beliefs regarding the causes of and risk factors for these disorders. Results A total of 317 health care professional (> 90% nurses) were surveyed from across the UAE. Although 43.8% correctly endorsed exposure to a ‘traumatic event’ as the most likely cause for developing posttraumatic stress disorder, there was a more limited understanding of the contribution of biopsychosocial factors to the development of the mental illness, particularly for psychosis. Participant socio-demographic variables were associated with attributions of religious or spiritual beliefs and personal weakness as causal and/or vulnerability factors in the development of depression with suicidal thoughts and psychosis. Conclusions Efforts to improve mental health systems and health care providers in UAE and other similar Middle Eastern countries requires targeted mental health literacy programs that seek to integrate biopsychosocial models of mental illness and their treatment with the positive aspects of religious and cultural beliefs that are dominant in this region

Factors Associated with High Prevalence of Intestinal Protozoan Infections among Patients in Sana'a City, Yemen

Intestinal protozoan diseases in Yemen are a significant health problem with prevalence ranging from 18% to 27%. The present study is a cross-sectional study aimed at determining the factors associated with the high prevalence of intestinal protozoan infections among patients seeking health care in Sana'a City, the capital of Yemen. (0.4%). Multivariate analysis using forward stepwise logistic regression based on intestinal protozoan infections showed that contact with animals (OR = 1.748, 95% CI = 1.168–2.617) and taking bath less than twice a week (OR = 1.820, 95% CI = 1.192–2.779) were significant risk factors of protozoan infections. infections being most common. Statistical analysis indicated that low personal hygiene and contact with animals were important predictors for intestinal protozoan infections. As highlighted in this study, in order to effectively reduce these infections, a multi-sectoral effort is needed. Preventive measures should include good hygienic practices, good animal husbandry practices, heightened provision of educational health programs, health services in all governorates including rural areas. Furthermore, it is also essential to find radical solutions to the recent water crises in Yemen

“We are women and men now”: Intimate spaces and coping labour for Syrian women refugees in Jordan

War affects women from the bedroom to the battlefield, but for most women war is experienced within intimate spaces. Intimate spaces are rarely the focus of mainstream academic research or media reporting; thus women\u27s experiences with war and displacement are often concealed. Building from literature in feminist geopolitics that helps focus our attention toward everyday and intimate geopolitics, I conducted in‐depth interviews with Syrian women refugees in Jordan in order to examine how they are coping. Of the many ways that they\u27ve learned to cope, these women asserted that earning an income and adjusting to altered gender performances and relations have been both dire and formative. Many Syrian women refugees have become income providers for the first time in their lives. Some women have become their families’ sole providers, and other women are now heads of households as well. Bringing literature from feminist geography, transnational and migration studies, and critical home studies together with feminist geopolitics, I offer the ideas of coping and coping labour as a framework to examine the intimate spaces of displacement. I highlight that paid work is understudied within feminist geopolitics, but such a focus renders important insights into how gender shapes experiences of displacement and how displacement is reshaping gendered relations. In this paper, I show that in the intimate spaces of displacement women have taken on traditionally masculine practices, but while their gendered performances shift, they are simultaneously entrenched as the ideals of appropriate feminine and masculine performances are recreated. Though these multiple gendered performances are creating numerous demands and challenges for Syrian women refugees, these women are also experiencing an increased sense of strength, confidence and respect as a result of their shifting performances