Petroleum Development Oman (PDO) is currently redeveloping a thick deep heavy oil reservoir using steam flooding. Steam has been injected in the first inverted 7-spot pattern (1P) since late 2008. An areal surveillance plan was created together with Shell International EP (SIEP) to test different monitoring techniques in order to select the most cost-efficient one for full field deployment. Ideally, the selected method would improve understanding of the thermal recovery concept and optimise further pattern development. The plan included three crosswell seismic profiles, 3DVSP and surface seismic, all in time-lapse mode. The 2006 surface seismic was used as the baseline for the surface seismic acquired in 2012. The data shows very good repeatability. However as the project construction phase took place after 2006, the 4D surface seismic was influenced by the 4D noise caused by surface changes. Detecting 4D signals is challenging particularly with the relatively small amount of injected steam. In contrast, crosswell seismic data and the 3DVSP were acquired after the construction work took place. The crosswell seismic 4D velocity profiles showed changes below and above top of reservoir, which lead to the consideration of geomechanical effects. The 3DVSP data indicated reservoir changes towards the north of the injector which is in line with the temperature surveys, also indicating preferential changes to the north. These encouraging results lead to a second monitor 3DVSP acquisition followed by a pilot 3DVSP using a fibre-optic cable installed in the well for distributed acoustic sensing (DAS). The second monitor 3DVSP shows that previous 4D signals have moved further towards north. It also indicates additional changes at the bottom perforation zone (as injection was shifted to bottom) with a preferential movement towards north as well. On the other hand DAS VSP was found comparable enough with the conventional VSP and therefore it can detect reservoir changes. A plan is on going to fit the existing observation wells with DAS cables and shoot a major 3DVSP baseline. The DAS cable will be combined with distributed temperature sensing (DTS) to maximize the value of the installation plan.
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机译：石油开发阿曼（PDO）目前正在使用蒸汽洪水重新开发厚厚的深层油藏。自2008年底以来的第一个倒立的7点模式（1P）注入了蒸汽。与Shell International EP（SIEP）一起创建了一个面积监测计划，以测试不同的监控技术，以便为满市选择最具成本效益的监控技术现场部署。理想情况下，所选方法将改善对热回收概念的理解，并优化进一步的模式开发。该计划包括三个Crosswell地震曲线，3DVSP和表面地震，全部间隔模式。 2006年表面地震用作2012年在2012年获得的表面地震的基线。数据显示了非常好的重复性。然而，随着项目建设阶段发生在2006年之后，4D表面地震受到表面变化引起的4D噪声的影响。检测4D信号特别是挑战，特别是具有相对少量的注射蒸汽。相比之下，在建造工作发生后获得了Crosswell地震数据和3DVSP。 Crosswell地震4D速度剖面显示出低于储层的变化和上方，导致对地质力学效应的考虑。 3DVSP数据指示储存器朝向注射器的北部变化，该喷射器沿着温度调查，也表明对北方的优先变化。这些令人鼓舞的结果导致第二监视器3DVSP采集，然后使用在井中安装的光纤电缆进行飞行员3DVSP进行分布式声学传感（DAS）。第二监视器3DVSP显示前一个4D信号已经向北移动。它还表示底部穿孔区（作为喷射移到底部）的额外变化，以及北方的优先运动。另一方面，发现DAS VSP与传统的VSP相当，因此它可以检测水库变化。计划是将现有的观察井与DAS电缆拍摄，并拍摄主要的3DVSP基线。 DAS电缆将与分布式温度传感（DTS）相结合，以最大化安装计划的值。
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