Abstract

The present study aims at finding the severity of the erosional damage for sudden-expansion geometries in a candidate oil well. A two-step approach is proposed for the localized erosion prediction in wells. At first, one-dimensional flow through the well strings is solved using the transient multiphase flow simulator, OLGA, which provides phase properties and flow conditions for the local erosion calculation. Then, the recorded flow data are employed for a detailed three-dimensional computational fluid dynamics (CFD)-based flow and erosion calculation in the selected sections of the well. In this study, two sudden-expansion geometries at substantially different depths are selected and investigated. Erosion magnitude and its pattern are evaluated for multiphase flow conditions and compared with single-phase flow. It is found that the erosional damage for the multiphase flow could be because of the random impingements due to the pipe size effect on the multiphase flow regime which is an indirect effect of the flow transition through sudden-expansion. The most severe condition is encountered for the expansion geometry closer to the wellhead, but the annual erosion rate is below the critical rate. However, for the dry-gas wells when a liquid film is not present, the erosion rate could be significantly above the critical rate.

摘要

本研究旨在确定候选油井中突然膨胀几何形状的侵蚀损坏的严重程度。提出了一种用于井中局部侵蚀预测的两步法。首先，使用瞬态多相流模拟器 OLGA 求解通过井柱的一维流动，该模拟器为局部侵蚀计算提供相特性和流动条件。然后，记录的流动数据用于在井的选定部分进行详细的基于三维计算流体动力学 (CFD) 的流动和侵蚀计算。在这项研究中，选择并研究了两种深度完全不同的突然膨胀几何结构。针对多相流条件评估侵蚀量及其模式，并与单相流进行比较。研究发现，多相流的冲蚀损伤可能是由于管道尺寸对多相流态的随机冲击，这是通过突然膨胀的流动过渡的间接影响。靠近井口的膨胀几何形状遇到最严重的情况，但年侵蚀率低于临界率。然而，对于不存在液膜的干气井，侵蚀速率可能显着高于临界速率。但年侵蚀率低于临界率。然而，对于不存在液膜的干气井，侵蚀速率可能显着高于临界速率。但年侵蚀率低于临界率。然而，对于不存在液膜的干气井，侵蚀速率可能显着高于临界速率。