Poroelastic contribution to the reservoir stress path
Poroelastic contribution to the reservoir stress path
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DOI：
10.1016/j.ijrmms.2010.08.001
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发表时间：
2010-10
影响因子：
7.2
通讯作者：
J. Altmann;Tobias Malte Müller;B. Müller;M. Tingay;O. Heidbach
中科院分区：
文献类型：
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作者：
J. Altmann;Tobias Malte Müller;B. Müller;M. Tingay;O. Heidbach
孔隙压力/应力耦合是与孔隙压力P变化相关的较小水平应力σ h的变化，并且已经在世界范围内的许多储层中测量到。这些测量结果表明，最小水平应力的变化Δσ平均约为0.001。64%的储层孔隙压力变化ΔP，但可以低至34%，高至118%。通常认为，与水平应力σ和σh不同，覆盖层产生的总垂直应力σv不受孔隙压力变化的影响。通过解析和数值模拟方法研究了点源连续注液条件下多孔弹性介质中孔隙压力和应力的时空演化规律，并计算了Δσ/ΔP比值。分析表明，实测的Δσh/ΔP的平均值可以从点源流体注入引起的孔隙压力和水平应力的时空演化的长期极限数学推导出来。我们将数值结果与均匀孔隙弹性介质中连续点注入的解析解以及现场测量的Δσh/ΔP值进行了比较，并表明所有应力分量都随P的变化而变化。我们使用孔隙弹性的概念来解释在储层中观察到的孔隙压力和应力之间的耦合，我们认为不同的测量地点和测量时间是造成全球不同油田Δσh/ΔP测量值变化的一个可能原因。
Pore pressure/stress coupling is the change in the smaller horizontal stress σhassociated with changes in pore pressure P, and has been measured in numerous reservoirs worldwide. These measurements suggest that the change in minimum horizontal stress Δσhis on average ca. 64% of the change in the reservoir pore pressure ΔP, but can be as low as 34% and as high as 118%. Conventionally it is assumed that the total vertical stress σv, given by the overburden, is not affected by changes in pore pressure, in contrast to the horizontal stresses σHand σh. We investigate analytically and numerically the spatio-temporal pore pressure and stress evolution in poroelastic media for continuous fluid injection at a point source, and calculate from the numerical modelling results the ratio Δσ/ΔP. Analytically, we show that the measured average of Δσh/ΔP can mathematically be deduced from the long-term limit of the spatio-temporal evolution of pore pressure and horizontal stress caused by fluid injection at a point source. We compare our numerical results to the analytical solution for continuous point injection into homogeneous poroelastic media as well as to Δσh/ΔP values measured in the field, and show that all stress components change with a variation in P. We use the concept of poroelasticity to explain the observed coupling between pore pressure and stress in reservoirs, and we consider different measurement locations and measurement times as one possible reason for the measured variation in Δσh/ΔP in different oil fields worldwide.