牛顿流体-幂律流体双区复合稠油油藏水平井热采试井模型

Horizontal Well Test Model of Thermal Recovery in the Heavy Oil Reservoir with Composite Dual-Zone of Newtonian and Power-Law fluids

针对压敏型稠油油藏水平井热采开发,综合考虑油藏渗透率应力敏感及稠油的幂律特性,建立了牛顿流体-幂律流体双区复合稠油油藏水平井试井模型,运用有限元方法求解水平井井底压力。结果表明:该模型可分为8个流动阶段,无因次应力敏感系数越大,压力导数曲线上翘程度越大;将外区(冷油区)处理为幂律流体时,外区径向流阶段压力导数曲线变为斜直线,内外区导压系数之比越大,幂律区反应特征越明显,压力导数曲线上翘越明显;蒸汽区(内区)半径变小,压力波在内区中传播的时间变短,即内区径向流结束时间也越早。应用该模型对新疆G区块进行试井解释,拟合精度高于传统模型。该方法为稠油油藏热采精细描述开辟了新途径,对稠油油藏试井解释具有重要意义。

Based on the thermal recovery performance of heavy oil reservoir with stress sensitivity,a horizontal well test model of thermal recovery in the heavy oil reservoir with composite dual zone of Newtonian and power-law fluids was established by considering the stress sensitivity of reservoir permeability and the power-law performance of heavy oil.The finite element was adopted to solve the horizontal well bottom-hole pressure.Result indicates that this model can be separated into 8 flow stages.The upward level of the pressure derivative curve increases with the increase of the dimensionless stress sensitivity coefficient.When the outer zone(cold oil zone)is treated as a power-law fluid flow,the pressure derivative curve becomes a straight line during radial flow stage in the outer zone.The fluid flow shows a favorable power-law performance and the upward level of pressure derivative curve increases with the increase of the inner-outer pressure diffusivity coefficient ratio.The inner radial fluid flow period decreases with the decrease of steam zone radius(inner zone)and the inner pressure propagation period.This model was used to in the well test interpretation of Xinjiang Block G,which shows a higher fitting accuracy than that of conventional models.This research could give a new means to the fine characterization of thermal recovery in heavy oil reservoir,which is of great significance for the well test interpretation in heavy oil reservoir.