稠油注蒸汽开采蒸汽腔扩展形态4D微重力测量技术

Description of steam chamber shape in heavy oil recovery using 4D microgravity measurement technology

4D微重力测量技术利用不同时期重复测量的重力数据研究地下介质,特别是地下流体的变化状态及过程。根据辽河油田杜84块馆陶组超稠油油藏蒸汽辅助重力泄油开采实际情况,建立了微重力变化计算模型。利用不同时期测得的研究区4D微重力场,经小波变换剥离目的层区域场,得到反映注汽层和稠油层密度变化的剩余重力异常分布,以20μGal为主体异常,分析得到蒸汽腔分布图,作出2次观测的蒸汽腔叠合图,以定量描述蒸汽辅助重力泄油开采过程中蒸汽腔的变化形态。数值模拟及井温测试验证了该技术的可行性。现场可根据蒸汽腔的形态及变化及时调整注汽方案,如Gh12井调整后产量明显改善,由2010年5月的65.4 t/d恢复到2012年5月的82.8 t/d。

4D microgravity measurement is used to study the underground medium, especially underground fluid variation state and process, using repeated measurements of gravity data at different periods. A model of microgravity variation calculation for the Guantao Formation in the Du 84 block of the Liaohe Oilfield was established according to the practical condition of the steam assisted gravity drainage （SAGD） of super heavy oil reservoir. The distribution of residual gravity that reflects the density change of the steam injection layer and heavy oil layer can be obtained using the target area 4D microgravity measured at different periods through wavelet transformation. With -20 μGal as the main anormaly, the variation of steam chamber shape in the steam assisted gravity drainage can be quantitatively described by analyzing the distribution of steam chamber, and drawing the steam chamber overlapping map of two observations. Numerical simulation and well temperature test verified the feasibility of the technology. The result from the technology can be used to adjust steam injection scheme timely according to the morphological changes in the steam chamber, for example, the Ghl2 well has got good results, with oil production going up from 65.4 t/d in May 2010 to 82.8 t/d in May 2012 after adjustment of its injection scheme.