The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Jin Yang - One of the best experts on this subject based on the ideXlab platform.
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study of Mud Weight window of horizontal wells drilled into offshore natural gas hydrate sediments
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Wenlong Li, Jin YangAbstract:Abstract Drilling horizontal wells into natural gas hydrate (NGH) sediments may be one of the most promising methods to increase the cost effectiveness of the exploration of NGH. However, many challenges, such as wellbore collapse and wellbore fracturing, will be encountered. Therefore, an accurate prediction of the Mud Weight window (MWW) is very important. In this work, a model was built to calculate the MWW of horizontal wells drilled into offshore NGH sediments, considering the NGH saturation and the effects of inlet parameters of the drilling Mud, and was combined with the transient heat transfer model to calculate the temperature distribution of the borehole. A case study was carried out, and the effects of several parameters were discussed: 1) When drilling horizontal wells in NGH sediments, the dissociation of NGH in the formation will not occur. 2) With increasing circulation time, the borehole will be cooled, and the cooling effect will lead to a decrease in both the fracture pressure and collapse pressure of the target zone. 3) The Mud flow rate has a large influence on the Mud temperature profile, especially in the horizontal section, and a higher Mud flow rate leads to a lower fracture pressure and collapse pressure in the target zone. 4) The inlet temperature has limited influences on the Mud temperature profile in the horizontal section and the MWW of the target zone. 5) The saturation of NGH in a formation has a significant influence on the collapse pressure but little influence on the fracture pressure, and higher saturation will lead to a wider MWW. This study will support the safe control of well stability and application of horizontal wells drilled into offshore NGH sediments.
Chunhe Yang - One of the best experts on this subject based on the ideXlab platform.
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uncertainty evaluation of safe Mud Weight window utilizing the reliability assessment method
Energies, 2019Co-Authors: Tao Tang, Ping Chen, Chunhe YangAbstract:Due to the uncertainty of formation properties and improper wellbore stability analysis methods, the input parameters are often uncertain and the required Mud Weight to prevent wellbore collapse is too large, which might cause an incorrect result. However, the uncertainty evaluation of input parameters and their influence on safe Mud Weight window (SMWW) is seldom investigated. Therefore, the present paper aims to propose an uncertain evaluation method to evaluate the uncertainty of SMWW. The reliability assessment theory was introduced, and the uncertain SMWW model was proposed by involving the tolerable breakout, the Mogi-Coulomb (MG-C) criterion and the reliability assessment theory. The influence of uncertain parameters on wellbore collapse, wellbore fracture and SMWW were systematically simulated and investigated by utilizing Monte Carlo simulation. Finally, the field observation of well SC-101X was reported and discussed. The results indicated that the MG-C criterion and tolerable breakout is recommended for wellbore stability analysis. The higher the coefficient of variance is, the higher the level of uncertainty is, the larger the impact on SMWW will be, and the higher the risk of well kick, wellbore collapse and fracture will be. The uncertainty of basic parameters has a very significant impact on SMWW, and it cannot be ignored. For well SC-101X, the SMWW predicted by analytical solution is 0.9921–1.6020 g/cm3, compared to the SMWW estimated by the reliability assessment method, the reliability assessment method tends to give a very narrow SMWW of 1.0756–1.0935 g/cm3 and its probability is only 80%, and the field observation for well kick and wellbore fracture verified the analysis results. For narrow SMWW formation drilling, some kinds of advanced technology, such as the underbalanced drilling (UBD), managed pressure drilling (MPD), micro-flow drilling (MFD) and wider the SMWW, can be utilized to maintain drilling safety.
Hongkun Zhang - One of the best experts on this subject based on the ideXlab platform.
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strength varying laws of rock soaked with supercritical co2 drilling fluid and the prediction of safe Mud Weight window
Greenhouse Gases-Science and Technology, 2017Co-Authors: Hongkun ZhangAbstract:Drilling with supercritical CO 2 (SC‐CO 2 ) is an important new technology in petroleum engineering. The technology has many unique advantages for increasing the penetration rate and reducing formation damage, but it is a disadvantage for the wellbore stability. Therefore, an experimental technique has been developed to determine the safe Mud Weight window for drilling with SC‐CO 2 . More specifically, a special experimental apparatus has been designed to mimic the in situ temperature and pressure conditions during drilling operations. Different experiments were conducted using core samples soaked in SC‐CO 2 and water‐based and oil‐based drilling fluids, respectively. Once the experimental measurements regressed, an empirical correlation, including time, temperature and pressure factors, was obtained to describe the compressive strength of the SC‐CO 2 ‐soaked core samples. Further modifications were then made to the formulations used to calculate the densities of the drilling fluids at the corresponding burst and collapse pressure, respectively. In addition, the effects of dynamic cohesion, internal friction angle, and tensile strength on the wellbore stability were determined. Compared to the conventional water‐based and oil‐based drilling fluids, the SC‐CO 2 drilling fluid performs better with respect to wellbore stability and has a wider safe Mud Weight window. © 2016 Society of Chemical Industry and John Wiley & Sons, Ltd.
Vamegh Rasouli - One of the best experts on this subject based on the ideXlab platform.
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practical application of failure criteria in determining safe Mud Weight windows in drilling operations
Journal of rock mechanics and geotechnical engineering, 2014Co-Authors: Raoof Gholami, Ali Moradzadeh, Vamegh Rasouli, Javid HanachiAbstract:Abstract Wellbore instability is reported frequently as one of the most significant incidents during drilling operations. Analysis of wellbore instability includes estimation of formation mechanical properties and the state of in situ stresses. In this analysis, the only controllable parameter during drilling operation is the Mud Weight. If the Mud Weight is larger than anticipated, the Mud will invade into the formation, causing tensile failure of the formation. On the other hand, a lower Mud Weight can result in shear failures of rock, which is known as borehole breakouts. To predict the potential for failures around the wellbore during drilling, one should use a failure criterion to compare the rock strength against induced tangential stresses around the wellbore at a given Mud pressure. The Mohr–Coulomb failure criterion is one of the commonly accepted criteria for estimation of rock strength at a given state of stress. However, the use of other criteria has been debated in the literature. In this paper, Mohr–Coulomb, Hoek–Brown and Mogi–Coulomb failure criteria were used to estimate the potential rock failure around a wellbore located in an onshore field of Iran. The log based analysis was used to estimate rock mechanical properties of formations and state of stresses. The results indicated that amongst different failure criteria, the Mohr–Coulomb criterion underestimates the highest Mud pressure required to avoid breakouts around the wellbore. It also predicts a lower fracture gradient pressure. In addition, it was found that the results obtained from Mogi–Coulomb criterion yield a better comparison with breakouts observed from the caliper logs than that of Hoek–Brown criterion. It was concluded that the Mogi–Coulomb criterion is a better failure criterion as it considers the effect of the intermediate principal stress component in the failure analysis.
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determination of safe Mud Weight windows for drilling deviated wellbores a case study in the north perth basin
WIT transactions on engineering sciences, 2012Co-Authors: K Le, Vamegh RasouliAbstract:Drilling non-vertical wells, which is commonly used to enhance production, in particular in unconventional reservoirs with very low permeability, is subjected to rock mechanics related issues namely wellbore instabilities. Drilling in the same formation but with different deviations and at different directions would not result in similar response in terms of rock failures. This is due to the rotation of the induced stresses around the wellbore wall along its trajectory. The type of instabilities that the formation experiences around the wellbore is a function of formation’s mechanical properties and the status of in-situ stresses. It is clear that none of these natural parameters can be controlled or changed during drilling operation. However, the density of the Mud weigh which is used to drill the wellbore could be optimised in order to mitigate or stop wellbore instability issues in the form of tensile failure or fracturing in case of using high Mud density or shear failure or breakouts when a low Mud weigh is used. Therefore, a safe Mud Weight window (MWW) can be determined for optimum drilling in terms of having the least issues related to wellbore instabilities. This MWW will change as the wellbore deviation changes. In this paper, the concept of constructing the rock mechanical model (RMM) which includes the rock mechanical properties as well as in-situ stress profiles is briefly presented. Then the RMM output corresponding to vertical well Arrowsmith-1 which is a shale gas well drilled in the North Perth Basin of Australia will be used to calculate the safe MWW for drilling wellbores in different azimuth and deviation in the field. The results indicate how the MWW changes as a function of wellbore trajectory.
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A log based analysis to estimate mechanical properties and in-situ stresses in a shale gas well in North Perth Basin
WIT transactions on engineering sciences, 2012Co-Authors: S. Archer, Vamegh RasouliAbstract:In drilling operation the design of a proper Mud Weight to avoid any instability’s is important. A low Mud Weight may cause breakouts around the borehole whereas a high Mud Weight can fracture the formation. Mud Weight design is based on two main factors: the mechanical properties of formations being drilled and the state of in-situ stresses in the field. While drilling in soft formations are thought to be more prone to drilling related issues than hard formations, there are several cases where opposite observations have been reported. This is indeed due to a high stress anisotropy which can apply a large shear stress to the rock to fail it. As it is seen, in order to define the stable Mud Weight windows for drilling it is important to not only have a good understanding about the mechanical properties of formations but also a good estimation of the state of stresses in the field.In this study we used a log based methodology to extract rock elastic and strength properties as well as the magnitude of stresses including vertical and maximum and minimum horizontal stresses. This is based on the fundamental relationship between physical properties of rocks as captured in petrophysical logs (such as sound velocity or density) and mechanical properties, such as uniaxial compressive strength.
Wenlong Li - One of the best experts on this subject based on the ideXlab platform.
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study of Mud Weight window of horizontal wells drilled into offshore natural gas hydrate sediments
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Wenlong Li, Jin YangAbstract:Abstract Drilling horizontal wells into natural gas hydrate (NGH) sediments may be one of the most promising methods to increase the cost effectiveness of the exploration of NGH. However, many challenges, such as wellbore collapse and wellbore fracturing, will be encountered. Therefore, an accurate prediction of the Mud Weight window (MWW) is very important. In this work, a model was built to calculate the MWW of horizontal wells drilled into offshore NGH sediments, considering the NGH saturation and the effects of inlet parameters of the drilling Mud, and was combined with the transient heat transfer model to calculate the temperature distribution of the borehole. A case study was carried out, and the effects of several parameters were discussed: 1) When drilling horizontal wells in NGH sediments, the dissociation of NGH in the formation will not occur. 2) With increasing circulation time, the borehole will be cooled, and the cooling effect will lead to a decrease in both the fracture pressure and collapse pressure of the target zone. 3) The Mud flow rate has a large influence on the Mud temperature profile, especially in the horizontal section, and a higher Mud flow rate leads to a lower fracture pressure and collapse pressure in the target zone. 4) The inlet temperature has limited influences on the Mud temperature profile in the horizontal section and the MWW of the target zone. 5) The saturation of NGH in a formation has a significant influence on the collapse pressure but little influence on the fracture pressure, and higher saturation will lead to a wider MWW. This study will support the safe control of well stability and application of horizontal wells drilled into offshore NGH sediments.
