The narrow operating window between pore PRESSURE and fracture PRESSURE makes drilling difficult in some operations. A feasibility study of managed PRESSURE drilling (MPD) is carried out on Iran Darquain oil FIELD. The previous wells drilled in this FIELD showed that mud returns were lost during drilling Gadvan formation. The present work addresses this problem by means of surface back PRESSURE application in Darquain oil FIELD. The methodology employed in this study is based on hydraulic analysis calculations and comparative drilling operation PRESSUREs. The DZxION MPD software performs hydraulic analysis using the API RP 13D rheological model and calculates the annular PRESSURE drop to compare the PRESSUREs and the required back PRESSURE, if needed. Using a mud weight of 14.31 ppg and exerting 100 psi static back PRESSURE, the wellbore PRESSURE profile got slightly overbalanced. When the mud pumps are in service, no back PRESSURE is required. The problem is resolved and no kick or loss is observed using a MW of 14.31 ppg and a static back PRESSURE of 100 psi. As a result, the managed PRESSURE drilling technology is useful in Iran Darquian oil FIELD through using a lower mud weight in order to overcome the circulation loss in Sarvak formation. This study is based on hydraulic analysis calculations and comparing the drilling operation PRESSUREs in Darquain oil FIELD. For analyzing the PRESSURE regimes throughout the well, DZxION managed PRESSURE drilling software performs hydraulic analysis. This software calculates annular PRESSURE drop and equivalent circulating density to compare the PRESSUREs and required back PRESSURE, if needed. By using this method to drill the well, some advantages were gained: the mud weights used to drill the well, the number of casing strings, and the number of changing mud weights were reduced.

In the present work, the dynamics of a single spherical gas bubble surrounded by a rheopectic fluid obeying the Quemada model is numerically investigated while the bubble undergoes oscillatory motion due to acoustic forcing. The generalized form of the Rayleigh–Plesset equation has been used for studying bubble dynamics in Quemada fluids. The integro-differential equation representing the dynamics of the bubble is solved numerically using the finite-element method (FEM) and also the Gauss–Laguerre quadrature (GLQ) method. The effect of rheopexy number (Rx) and viscosity ratio (ξ) are then investigated over a wide range of working parameters. Numerical results show that the rheopectic behavior of the fluid surrounding the bubble can dramatically affect the bubble dynamics. It is predicted that for highly anti-thixotropic fluids, harmonics are affected so much so that the bubble may exhibit chaotic behavior. For instance, at Rx = 0. 001 and ξ = 1/81, a one-micron-sized bubble may attain a size almost 30 times of its initial size. The general conclusion is that, in sonography, microbubbles dispersed in rheopectic fluids may indeed be considered as a potent ultrasound contrast agent provided that the fluid is just moderately anti-thixotropic otherwise its chaotic response might damage the adjacent tissues.

Background: Idiopathic intracranial hypertension (IIH) is an increased intracranial PRESSURE with normal cerebrospinal fluid (CSF) characteristic in the absence of identifiable causes. The most important complication of this disorder is visual impairment. So far, no comprehensive study has been done on the relationship between the opening CSF PRESSURE and visual FIELD defect in IIH. Methods: In this study, 35 patients with increased intracranial PRESSURE who fulfilled modified Dandy’ s criteria underwent ophthalmologic examination and lumbar puncture. The opening CSF PRESSURE was categorized into mild (25-30), moderate (30-40) and severe (>40). The degree of visual FIELD defect was reported both quantitatively and qualitatively. Eventually, the statistical relationship was established among these variables. Results: The mean opening CSF PRESSURE was 33. 71 CmH2o. Twelve patients had minor CSF PRESSURE, whereas in 14 and 9 patients the CSF PRESSURE was respectively moderate and severe. There was not statistically significant relationship between the visual FIELD defect and CSF PRESSURE. The most common patterns of visual FIELD involvement were enlarged blind spot and peripheral restriction. Conclusion: The most important morbidity in IIH is visual impairment. According to the findings, the visual FIELD impairment is not pertinent to CSF PRESSURE. In other words, neither high CSF PRESSURE predicts intense visual defect, nor low CSF PRESSURE indicates minimal visual impairment.