Fracture aperture is usually estimated by cubic law, which assumes flow between two smooth parallel plates. However, many researchers have proved that the fracture aperture is not a smooth surface but rather has tortuous paths and roughness, and hence the flow behavior is different. Previous research showed that fracture aperture follows lognormal distribution. Nevertheless, there has not been any research conducted to validate the fracture aperture distribution with the change in stress conditions, which is common in fractured reservoirs. With the advent of X-ray CT scanner in the field of petroleum engineering, fracture apertures can be visualized and measured. Since there is no direct calculation for fracture aperture measurement from CT scanner data, a calibration curve needs to be established. We developed a calibration curve based on existing calibration techniques, which involves area integration of the fracture region to obtain a correlation between integrated CT numbers and the calibrated fracture aperture. Using this calibration curve, we obtained distribution patterns for fracture apertures along the length of the core for various stress conditions, from about six thousand fracture aperture measurements for each stress condition. The results show that aperture distributions still follow lognormal distribution under various stress conditions.
Hidradenitis suppurativa (HS) is a chronic relapsing, remitting disease which results in the formation of inflammatory nodules and pustules in intertriginous areas. HS is a complex disease with known psychosocial impact. Adalimumab is a biologic, used for treatment resistant HS, which working by inactivating TNF‐alpha. Our primary objective was to determine the effects of adalimumab on HS‐PGA and DLQI scores in patients with HS that had been on the treatment for at least 6 months. Our secondary objective was to note and assess the significance of adverse effects and impacts on wider health, namely occupational and social. A retrospective cross‐sectional study was performed using clinic notes from routine follow ups in biologic clinics in three specialist HS centers. About 77% (n = 78/101) patients demonstrated improvements in their HS‐PGA scores. Significant improvements in the DLQI scores of the patient cohort (P = .0001, 95% CI −12.8 to −5.9) have also been demonstrated. A total of 31.7% (32/101) patients experienced adverse effects spanning multiple organ systems, with 27.7% (28/101) requiring treatment cessation. Three of these patients stopped due to the worsening of preexisting mental health symptoms. Adalimumab is effective in reducing HS‐PGA and DLQI scores, but patients still complain of systemic effects necessitating drug cessation in some instances. A holistic and multisystemic approach to follow up is required, and there is scope for further studies examining temporal causality in the context of adalimumab and its multisystemic physical and psychological effects.
Fractured reservoirs have always been considered poor candidates for enhanced oil recovery. This is mainly due to the complexities involved in predicting performance in such reservoirs. A good understanding of multiphase flow in fractures is important to reduce oil bypass and increase recovery in these reservoirs. This paper presents CO 2 flooding experiments in homogeneous and fractured rocks with in-situ saturation and porosity measurements using an X-Ray CT scanner. We found that injection rates played an important role in the recovery process, more so in the presence of fractures. At high injection rates we observed faster CO 2 breakthrough and higher oil bypass than at low injection rates. But very low injection rates are not attractive from an economic point of view. Hence we injected viscosified water to reduce the mobility of CO 2 , similar to the WAG process. Breakthrough time reduced significantly and a much higher recovery was obtained. Saturation measurements were made from the CT scans and were found to be in good agreement with those obtained from effluent data.
This work considers the control of a spacecraft in indefinite near-rectilinear halo orbit about the Earth-Moon L2. For indefinite station-keeping, it is important to minimize fuel consumption, while allowing for occasional transfer to a new orbit. The control scheme therefore consists of two components: the first component is the tracking of the nominal NRHO and the second component is an orbit correction maneuver between NRHO trajectories. The nominal NRHO is computed using a multiple-shooting technique that takes into account all forces on the spacecraft whose magnitude is larger than the dominant disturbance forces caused by navigational error. The tracking component is a linear-quadratic regulation scheme that rejects disturbances caused by orbit determination error, using a Lyapunov sublevel set that models the state covariance generated using sequential Kalman filter. The orbit correction maneuver is computed to minimize fuel costs.
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