椭圆形井眼环空压力梯度预测与影响因素分析

王江帅; 李军; 柳贡慧; 赵贺谦; 吴雪婷; 邹韵

doi:10.3969/j.issn.1001-5620.2018.05.003

椭圆形井眼环空压力梯度预测与影响因素分析

doi: 10.3969/j.issn.1001-5620.2018.05.003

1. 中国石油大学(北京)石油工程学院, 北京 102249;
2. 北京工业大学, 北京 100192;
3. 西安石油大学地球科学与工程学院, 西安 710065

基金项目:

国家自然科学基金重点项目“深水油气钻采井筒压力控制基础研究”（51734010），“控压钻井测控理论及关键问题研究”（51334003）。

详细信息

作者简介:
王江帅,在读博士研究生,主要从事控压钻井与井控方面的研究。电话15191446097;E-mail:1183472804@qq.com。

中图分类号: TE283
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出版历程
- 收稿日期: 2018-05-28
- 刊出日期: 2018-09-30

Annular Pressure Gradients of Elliptical Wellbore: Prediction and Influential Factor Analysis

1. School of Petroleum Engineering, China University of Petroleum, Beijing 102249;
2. Beijing University of Technology, Beijing 100192;
3. College of Earth Sciences & Engineering, Xi'an Shiyou University, Xi'an 710065

摘要

摘要: 井筒压力梯度的准确预测是井底压力精确控制的必要条件，其有利于减小井下复杂情况的发生。常规的压力梯度模型建立在井眼是圆形的基础上。然而，由于非均匀地应力的影响，实际井眼常常为椭圆形状，椭圆形井眼环空流动规律与圆形环空流动规律有着显著不同。基于流体力学的基本方程，笔者引入了有效水力直径，建立了椭圆形井眼环空流动的压降模型。研究表明，随着椭圆井眼尺寸比的增大，环空平均流速减小，压力梯度也随之减小；并且椭圆井眼尺寸比越大，环空环形方向高、低流速区域分级现象越加明显。另外，与CFD软件模拟结果相比，该模型的误差在±10%以内。影响因素分析表明，其他条件不变时，椭圆形井眼环空井筒压力梯度随流量、流体动切力和稠度系数的增大基本呈线性形式增大，而随流性指数的增大基本呈指数形式增大，模型能够用来计算椭圆形井眼的井筒压力。
- 压力梯度 /
- 椭圆形井眼 /
- 有效水力直径 /
- 压降模型 /
- CFD软件
Abstract: Th establishment of conventional pressure gradient models is based on the idea that the cross section of a wellbore is round, however, in practical situation, the cross section of a wellbore is elliptical under the influence of non-uniform in-situ stresses. The flow pattern in annular space of an elliptical cross-section wellbore is obviously different to the flow pattern in annular space of a round cross-section wellbore. Based on the basic equations of fluid mechanics, a concept of "effective hydraulic diameter" has been introduced in establishing a pressure loss model of annulus flow in elliptical wellbore. Studies showed that with an increase in the ratio of long radius over short radius of an elliptical wellbore, the average flowrate in the annular space decreases, and the annular pressure gradient decreases with it. The greater the ratio of the long radius over the short radius of an elliptical wellbore, the more obvious the grading of the high and low flowrate areas along the helix direction of the annular space. Furthermore, compared with simulation results (using the CFD software), this model has calculation errors that are in a range of less than ±10%. Analyses of affecting factors indicated that when other conditions remain constant, the annular pressure gradient of a elliptical wellbore increases somewhat linearly with increases in annular flowrate and yield point and consistency index of the fluid, and somewhat exponentially with increases in flow index. The model established based on the studies can be used to calculate the wellbore pressure of an elliptical wellbore.
- Pressure gradient /
- Elliptical wellbore /
- Effective hydraulic diameter /
- Pressure loss model /
- CFD software

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参考文献(12)

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