含水率对岩石强度及出砂影响研究

Study on the Effect of Water Content on Rock Strength and Sand Production

储层含水量增加,岩石的强度减小,出砂风险增大。油藏出砂将降低油气产量,损害井下装置和地面设施。针对流花油田弱胶结储层,开展储层岩石不同含水饱和度时的单轴强度实验,揭示了出水对储层出砂影响的机理,并通过经验方法对不同含水率储层的临界生产压差进行预测。结果表明:含水饱和度与岩石单轴强度呈指数递减规律。含水饱和度越高,岩样的单轴抗压强度越低。含水率对岩石强度及出砂影响程度,取决于砂岩内蒙脱石、伊蒙混层等易水化黏土矿物的含量和含水率大小。

With the increase of water content, rock strength decreases, and the potential risk of sand produc- tion will increase. Sand production will reduce oil and gas production and damage downhole devices and ground fa- cilities. Aiming at weakly/poorly sandstone reservoirs in Liuhua oilfield, uni-axial compressive strength experiments of rock in different water saturation are conducted, and revealed the mechanism of effect of yielding water on sand production,and predictsed critical producing pressure of reservoir through the empirical method in different water content. The experimental results show that the relation between water saturation and rock nni-axial strength is ex- ponential decline rule. The higher water saturation is, the lower uni-axia compressive strength is. The degree of effect of water content on rock strength and sand production depends on size of the content of easily hydrated clay mineral（ smectite, illite-smectite） and water saturation.