Constraint optimization of an integrated production model utilizing history matching and production forecast uncertainty through the ensemble Kalman filter.

The calibration of reservoir models using production data can enhance the reliability of predictions. However, history matching often leads to only a few matched models, and the original geological interpretation is not always preserved. Therefore, there is a need for stochastic methodologies for history matching. The Ensemble Kalman Filter (EnKF) is a well-known Monte Carlo method that updates reservoir models in real time. When new production data becomes available, the ensemble of models is updated accordingly. The initial ensemble is created using the prior model, and the posterior probability function is sampled through a series of updates. In this study, EnKF was employed to evaluate the uncertainty of production forecasts for a specific development plan and to match historical data to a real field reservoir model. This study represents the first attempt to combine EnKF with an integrated model that includes a genuine oil reservoir, actual production wells, a surface choke, a surface pipeline, a separator, and a PID pressure controller. The research optimized a real integrated production system, considering the constraint that there should be no slug flow at the inlet of the separator. The objective function was to maximize the net present value (NPV). Geological data was used to model uncertainty using Sequential Gaussian Simulation. Porosity scenarios were generated, and conditioning the porosity to well data yielded improved results. Ensembles were employed to balance accuracy and efficiency, demonstrating a reduction in porosity uncertainty due to production data. This study revealed that utilizing a PID pressure controller for the production separator can enhance oil production by 59% over 20 years, resulting in the generation of 2.97 million barrels of surplus oil in the field and significant economic gains.

Development of a rock-bit interaction analytical model by considering the in-situ stresses for a bottom-hole element.

PDC drill bits are an important part of drilling engineering, but improper selection or design can lead to decreased performance and increased costs. Then, accurate modeling of rock-bit interaction for Oil/gas well drilling is critical. Although several mathematical models are presented for this purpose, they have not been able to present a comprehensive model for the rock-bit interaction. In-situ stresses in real drilling conditions affect the force required for rock failure. However, the models proposed so far either have not considered the effects of in-situ stresses or have assumed that the rock failure angle in the downhole conditions is equal to the one calculated in the atmospheric conditions. In this work, after reviewing the background of studies conducted on the rock and bit interaction, with an analytical method, stresses applied to the bottom hole element are examined, including stresses resulting from bit and in-situ stresses. Based on the principle of superposition, the total stress imposed on the bottom hole element is calculated to determine the angle and force of rock cutting. Finally, a novel mathematical model of rock-bit interaction in vertical and deviated oil/gas wells drilling by Considering In-Situ Stresses is presented. Also, the study compares the current model to the Nishimatsu and Xin Ling models using data from a southwest field in Iran. The results show that the simplifying assumption made by previous models leads to a significant underestimation of the failure angle and the amount of force required to the rock failure, with reductions of up to 21% and 48%, respectively, in the case of a vertical well. In an inclined well, the current model predicts cutting force at about 0.14 of that predicted by the previous model.

Assessing effects of modification of middle meatal silastic splint after endoscopic sinus surgery for nasal polyps: A randomized controlled study.

PURPOSE: To investigate the efficacy of middle meatal silastic splint in preventing adhesions after bilateral endoscopic sinus surgery (ESS) for chronic rhinosinusitis with nasal polyps (CRSwNP), and to assess nasal symptoms and endoscopic findings in splinted and non-splinted sides. METHODS: After completion of ESS, silicon silastic splints were randomly inserted in the middle meatus of one nasal side, while no stent in the other side (control). The surgeon was blinded to the side selection, and splint insertion until removal after 1 week. Patients were followed -up after 1 week, 1 and 6 months. Each side of the nasal cavity was assessed for adhesions, crusting, pus, pain, nasal obstruction, and nasal discharge by endoscopic examination and visual analogue scale. RESULTS: Forty-nine patients (98 nasal sides) were included. At the 1st week visit, there was no significant difference between the splinted and non-splinted sides for all investigated parameters.After 1- month, adhesions were seen in 10% of the splinted sides, while it was in 26% of the non-splinted sides (P = 0.037).At the 6 -month follow-up visit, the adhesions rate remained 10% in the splinted sides, however the rate increased to 32% in the non-splinted sides (P = 0.007). All other examined parameters remained statistically insignificant between both sides throughout the follow -up visits. CONCLUSIONS: Middle meatal silastic splint is significantly reducing middle meatal adhesions with low complication rate in CRSwNP patients undergoing ESS. Our results support its usage when the middle turbinate is unstable or traumatized during surgery.

Predator chemical cues decrease attack time and increase metabolic rate in an orb-web spider.

Animals are able to assess the risk of predation and respond accordingly via behavioural and physiological changes. Web-building spiders are in the unique situation where they reside in the middle of their web and are therefore relatively exposed to predators. Thus, these spiders might moderate either their web-building behaviour or their behaviour on the web when exposed to the threat of predation. In this study, we experimentally explored how chemical cues from a predator influence foraging behaviour and metabolic rate in females of the orb-web spider Argiope keyserlingi We found that female spiders restricted their foraging time budget when exposed to the predator cues from a praying mantid: they responded 11% and 17% quicker to a vibratory stimulus compared with control and non-predator cues, respectively, and spent less time handling the prey. Moreover, spiders were less likely to rebuild the web under predator cues. Female A. keyserlingi exposed to the praying mantid cue significantly elevated their metabolic rate compared with the control group. Our findings revealed short-term modifications over the 2 week trials in foraging behaviour and the physiology of female spiders in response to predator cues. This study suggests that under predator cues the spiders move quicker and this could be facilitated by elevation in metabolic rate. Reduced foraging activity and less frequent web repair/rebuilding would also reduce the spiders' exposure to praying mantid predators.