Influence of solvent injection temperature in steam-solvent assisted gravity drainage process for heavy oil reservoirs of Brazilian Northeast
蒸汽-溶剂辅助重力泄油（ES-SAGD）是一种结合了热效应和混相效应的采油方式已在加拿大等重油储层地区成功应用。该方法使用两个平行的水平井，上部井注入蒸汽和溶剂，下部井产出石油。巴西尚未应用此方法，尤其是在东北部地区，那里有重油储层。基于此背景，本研究旨在研究ES-SAGD的应用，这些储层具有与巴西东北部相似的特征，特别是分析溶剂注入方案对ES-SAGD的影响。使用CMG商业软件进行数值模拟，分析了多种蒸汽-溶剂注入速度，并采用了两种溶剂注入温度（储层温度或蒸汽温度），以将由于高温引起的爆炸风险降到最低。结果表明，溶剂注入温度对石油开采有重大影响，注入热溶剂更有利于石油生产，因为冷溶剂会导致蒸汽冷却。然而，也可以注入冷溶剂（储层温度），并通过改变一些蒸汽属性来增加石油生产，避免爆炸风险。
CMG软件应用情况：
本研究中使用了CMG的几款模块来模拟多孔介质中的流动：WinProp（相态模拟）、Builder（前处理）和STARS（蒸汽、热采和高级过程油藏模拟器）。研究中考虑了一个具有巴西东北部地区特征的储层，所有结果都是使用CMG的商业热采模拟器STARS获得的。
Abstract
The solvent–steam assisted gravity drainage is an oil recovery process that combines the advantages of thermal and miscible effects, and it has been successfully tested, especially in Canada, where many heavy oil reservoirs are located. This method uses two parallel horizontal wells drilled one above the other, the upper injects steam and solvent and the lower produces oil. This process has not been applied yet in Brazil, where there are heavy oil reservoirs, especially in northeast region. Based on this context, this research aimed to study the application of the ES-SAGD process in a semisynthetic reservoir, with characteristics similar to those found in the Brazilian Northeast, specifically to analyze the influence of the solvent injection scheme on ES-SAGD. Numerical simulations were performed using commercial software from CMG. It was analyzed several steam-solvent injection rates, using two injected temperatures for solvent, (at reservoir or at steam temperature´s), in order to minimize explosion risks, that can be due to high temperatures. Results showed that solvent injection temperature has great influence on oil recovery, it is better for oil production when it is inject hot solvent, because cold solvent generates a cooling of the steam. However, it is possible to injected cold solvent (at reservoir temperature), and increase oil production, changing some steam properties, avoiding explosions risks.
Keywords: Steam-solvent injection; Heavy oil; ES-SAGD; Reservoir modeling; Enhanced oil recovery; Thermal method.
作者单位：
巴西里约热内卢大学（Universidade Federal do Rio Grande do Norte）。
