Gas Suspension Effects in Riser Unloading and Appropriate Modelling Approaches

Dalila Gomes, K. Fjelde, K. Bjørkevoll, J. Frøyen
{"title":"Gas Suspension Effects in Riser Unloading and Appropriate Modelling Approaches","authors":"Dalila Gomes, K. Fjelde, K. Bjørkevoll, J. Frøyen","doi":"10.1115/omae2020-18049","DOIUrl":null,"url":null,"abstract":"A kick entering a drilling riser and expanding upwards uncontrolled can lead to severe consequences such as riser unloading and riser collapse, and in the worst case a blowout scenario may evolve. If the riser is filled with water-based mud, the kick will normally migrate on its own to surface, but it has been observed both in small scale experiments and in field tests that small amounts of gas are trapped by the mud during the kick migration. In some cases, the kick is not able to reach the surface without additional circulation. Hence, a certain kick size may or may not lead to an unloading scenario depending on the effect of gas suspension in the drilling fluid.\n In this paper, two different modelling approaches for describing the unloading scenario will be compared and the differences will be highlighted. In the first approach, the single bubble model will be considered. Here the gas bubble is assumed to occupy the whole cross-sectional area, and it is fully separated from the mud regions. This will be solved by two different calculations methods, one that is taken from literature and one that is based on a shooting technique. The second and recommended approach is to use a transient drift flux model, which includes friction, acceleration terms, and gas slip. For the gas slippage model, different flow patterns will be accounted for, as will the suspension effect that causes small amounts of gas to be trapped by the mud. The drift flux model will be solved numerically using the explicit AUSMV scheme.\n The impact of gas suspension will be studied by varying the onset for gas suspension to determine from simulations whether a riser will be unloaded or the kick become fully trapped in the riser. In addition, a sensitivity analysis will be presented where kick size, riser ID and riser length are varied to determine when the riser will be unloaded. The different simulations presented solves physical equations of the unloading scenario to calculate pressure at BOP, displaced mud volume (pit gain), liquid mass in well, surface rates, riser friction, and depth profiles of the gas distribution at a certain time. the tables provide a comprehensive overview of which combinations of parameters lead to a trapped gas scenario or and which lead to unloading the riser.\n It is shown that a fully transient drift flux model can cover a vast range of different situations e.g. gas becomes fully trapped in the riser, the riser becomes fully unloaded, and situations where only a very small part of the kick reaches the surface. The simulations show how the dynamics of the scenarios are quite different. A single bubble model will not have this capability.","PeriodicalId":403225,"journal":{"name":"Volume 11: Petroleum Technology","volume":"29 1","pages":"0"},"PeriodicalIF":0.0000,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Volume 11: Petroleum Technology","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1115/omae2020-18049","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 1

Abstract

A kick entering a drilling riser and expanding upwards uncontrolled can lead to severe consequences such as riser unloading and riser collapse, and in the worst case a blowout scenario may evolve. If the riser is filled with water-based mud, the kick will normally migrate on its own to surface, but it has been observed both in small scale experiments and in field tests that small amounts of gas are trapped by the mud during the kick migration. In some cases, the kick is not able to reach the surface without additional circulation. Hence, a certain kick size may or may not lead to an unloading scenario depending on the effect of gas suspension in the drilling fluid. In this paper, two different modelling approaches for describing the unloading scenario will be compared and the differences will be highlighted. In the first approach, the single bubble model will be considered. Here the gas bubble is assumed to occupy the whole cross-sectional area, and it is fully separated from the mud regions. This will be solved by two different calculations methods, one that is taken from literature and one that is based on a shooting technique. The second and recommended approach is to use a transient drift flux model, which includes friction, acceleration terms, and gas slip. For the gas slippage model, different flow patterns will be accounted for, as will the suspension effect that causes small amounts of gas to be trapped by the mud. The drift flux model will be solved numerically using the explicit AUSMV scheme. The impact of gas suspension will be studied by varying the onset for gas suspension to determine from simulations whether a riser will be unloaded or the kick become fully trapped in the riser. In addition, a sensitivity analysis will be presented where kick size, riser ID and riser length are varied to determine when the riser will be unloaded. The different simulations presented solves physical equations of the unloading scenario to calculate pressure at BOP, displaced mud volume (pit gain), liquid mass in well, surface rates, riser friction, and depth profiles of the gas distribution at a certain time. the tables provide a comprehensive overview of which combinations of parameters lead to a trapped gas scenario or and which lead to unloading the riser. It is shown that a fully transient drift flux model can cover a vast range of different situations e.g. gas becomes fully trapped in the riser, the riser becomes fully unloaded, and situations where only a very small part of the kick reaches the surface. The simulations show how the dynamics of the scenarios are quite different. A single bubble model will not have this capability.
立管卸载过程中的气悬浮效应及相应的建模方法
井涌进入钻井隔水管并不受控制地向上扩展可能导致严重后果,如隔水管卸载和隔水管坍塌,在最坏的情况下可能演变为井喷。如果隔水管中充满水基泥浆,通常情况下,井涌会自行运移到地面,但在小规模实验和现场测试中都观察到,在井涌运移过程中,泥浆会捕获少量气体。在某些情况下,如果没有额外的循环,踢腿就无法到达地面。因此,一定的井涌大小是否会导致卸载,取决于钻井液中气悬浮的影响。在本文中,描述卸载场景的两种不同的建模方法将进行比较,并强调其差异。在第一种方法中,将考虑单泡模型。这里假设气泡占据了整个横截面积,并且与泥浆区完全分离。这将通过两种不同的计算方法来解决,一种是从文献中获得的,另一种是基于射击技术的。第二种也是推荐的方法是使用瞬态漂移通量模型,其中包括摩擦、加速度项和气体滑移。对于气体滑移模型,将考虑不同的流动模式,以及导致少量气体被泥浆捕获的悬浮效应。漂移通量模型将采用显式AUSMV格式进行数值求解。通过改变气悬浮的开始时间来研究气悬浮的影响,从而从模拟中确定立管是否会被卸载,或者井涌是否完全被困在立管中。此外,还将对溢流尺寸、隔水管ID和隔水管长度进行敏感性分析,以确定何时卸载隔水管。所提供的不同模拟解决了卸载场景的物理方程,以计算防喷器压力、泥浆排量(坑增益)、井中液体质量、地面速率、隔水管摩擦和特定时间气体分布的深度剖面。这些表格提供了一个全面的概述,说明了哪些参数组合会导致困气,哪些参数组合会导致卸载立管。结果表明,完全瞬态漂移通量模型可以涵盖各种不同的情况,例如气体完全困在立管中,立管完全卸载,以及只有很小一部分涌水到达地面的情况。模拟显示了这些情景的动态是多么的不同。单个气泡模型不具备这种能力。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
求助全文
约1分钟内获得全文 求助全文
来源期刊
自引率
0.00%
发文量
0
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:604180095
Book学术官方微信