油田注水用复合管受力性能研究

Mechanical Behavior Study of Composite Pipe for Oilfield Water Injection

近年来,一种新型纤维增强热塑性复合管开始在井下分层精细注水领域进行应用。研究了该复合管用于油田井下注水时在组合载荷作用下的尺寸及力学性能的变化规律。选取中国石油吉林油田某油井作为研究对象,该井井深1000m,正常注水压力25MPa,选取了上、中、下三处典型位置的组合载荷,并模拟管柱多种使用工况。试验过程中测量复合管的尺寸变化,模拟试验完成后进行破坏性试验,最终得到40℃和60℃下爆破值较常温分别下降7.6%和11.6%,说明温度对复合管爆破压力有较大影响。并且在一定温度范围内,轴向力和管材的伸长率几乎呈线性关系,内压对管材伸长具有一定的抑制作用。通过对组合载荷下复合管力学性能变化规律的研究,有助于指导该类型复合管更好地应用于井下注水领域。

In recent years,a new type of fiber reinforced thermoplastic composite pipe has been applied in downhole precision water injection.The main research content of this paper is to find the variation of geometrical dimensions and mechanical properties of this kind of pipes when used as downhole water injection pipe under combined loads.An oil well in Jilin Oilfield was selected as the research object.The well depth is 1 000 m,the normal water injection pressure is 25 MPa.Combined loads at three typical locations of upper,middle and lower were selected to simulate various operating conditions of pipe string.During the test,the geometrical changes of the composite pipe were measured.After the simulation test was completed,the destructive test was carried out.Finally,the burst pressure at 40 ℃ and 60 ℃ decreased by 7.6 % and 11.6 % respectively compared with that at the normal temperature.The results show that temperature has great influence on the burst pressure of composite pipe.Furthermore,within certain temperature range,the relationship between the axial force and the elongation of the pipe is almost linear.However,the internal pressure has an inhibitory effect on the elongation of the pipe.It is helpful for this type of composite pipe to be better applied in the field of downhole precision water injection by studying the variation of the mechanical properties of the composite pipe under combined loads.