金华—中台山区块致密砂岩储层井壁稳定判断及出砂预测

Judgment of wellbore stability and sand production prediction of tight sandstone reservoir in Jinhua—Zhongtaishan block

金华—中台山区块沙溪庙组无专层完钻、测试井,完井方式不明确。根据岩石破坏理论和出砂预测方法,结合储层岩心水化前后岩石力学参数,对工区气井进行气井生产过程中井眼力学稳定性判断及出砂预测。根据Mohr-Coulumb和Von.Mises剪切破坏理论,工区沙溪庙组不同井斜角气井井壁岩石所受最大剪切应力(平均42.69 MPa)均小于井壁岩石剪切强度(平均71.92 MPa);不同井斜角气井井壁岩石所受最大剪切应力均方根(平均43.05 MPa)均小于井壁岩石剪切强度均方根(平均46.64 MPa),不同井斜角气井生产过程中井壁稳定。力学计算法出砂预测表明,工区沙溪庙组不同井斜气井在不同生产压差下井壁岩石最大切向应力均小于考虑水化后的地层岩石抗压强度(138.7 MPa),不同井斜角气井在地层压力衰减条件下以最大生产压差生产不会出砂。以上研究成果对该区块沙溪庙组气井完井方法优选具有重要意义。

The Shaximiao Formation in Jinhua—Zhongtaishan block has no drilled and tested wells,and the completion mode is not clear.According to the rock failure theory and sand production prediction method,combined with rock mechanical parameters before and after reservoir core hydration,the wellbore mechanical stability and sand production prediction of gas wells in the work area during gas well production are determined.According to Mohr-Coulomb and Von.Mises shear failure theory,the maximum shear stress(average 42.69 MPa)of the wall rock of the gas wells with different inclined angles in the Shaximiao Formation of the work area is less than the shear strength of the wall rock(71.92 MPa on average);the root mean square of the maximum shear stress(43.05 MPa on average)is less than the root mean square(46.64 MPa on average)of the wall rock of the gas wells with different inclined angles.The result show the wellbore stability in the production process of gas wells with different inclination angles.The sand production prediction by mechanical calculation method shows that the maximum tangential stress of borehole wall rock in different inclined gas wells of Shaximiao Formation in the work area is less than the compressive strength of formation rock after hydration(138.7 MPa)under different production pressure difference.It is predicted that sand production is not easy for gas wells with different inclined angles even if they are produced at maximum production pressure difference.There achievement above have a great significance for the optimization of completion methods of Shaximiao gas wells in this block.