三元复合驱采油井用的固体缓释防垢剂

A Controllably Reliesing Scale Inhibitor for Downhole Use in Production Wells of ASP-Combinational Flooding Reservoir

由3种未指名化合物配制成兼具防腐蚀作用的防垢剂FHE,加入固化剂制成缓释防垢剂(防垢块)。在三元复合驱采出液中加入防垢剂FHE2.5mg/L,在55℃、72h静态挂片测试中防垢率为99.0%;加入防垢剂FHE2.5、4.0mg/L,在55℃、压力3MPa、168h动态模拟条件下挂片测试防垢率分别为74.9%、93.2%,由此得到防垢剂FHE的最佳浓度为4.0mg/L。防垢剂FHE与固化剂的最佳配比为3∶1。在去离子水中50℃时,防垢剂FHE从直径20mm、长20mm的防垢块中的静态溶出率由13.14%(0～48h)逐渐降至11.04%(144～192h)。在模拟井筒条件的实验装置上,求得50～55℃下,14～20h内从防垢块溶出的防垢剂在三元复合驱采出液中的浓度由4.31降至3.70mg/L,由相似性原理求得在井筒中使用的防垢块直径应为8mm,长度应为645mm。在一口螺杆泵采油井中使用防垢块,油井产量略有增加,泵电流下降4～6A。图1表5参3。

A scale inhibitor, FHE, possessing corrosion inhibiting property is prepared from 3 unnamed chemical substances and is mixed with a solidifying material to give a delayed reliesing scale inhibitor (DRSI). In experiments on scale deposition onto steel specimen from produced water of a ASP-flooding reservoir at 55℃, a scale inhibition rate of 99.0% is observed in 72 h under static condition with 2.5 mg/L FHE added and of 74.9% and of 93.2%—in 168 h at pressure 3 MPa under dynamic simulation conditions with 2.5 and 4.0 mg/L FHE added, respectively. The optimal dosage of FHE is 4.0 mg/L. The optimal mass ratio of FHE and solidifying material is 3∶1. In deionized water at 50℃ the rate of dissolving out of FHE from DRSI of 20 mm in diameter and 20 mm long decreases gradually from 13.14% in 0—48 h to 11.04% in 144—192 h. On an experimental device under simulation conditions of well flow the measured concentration of the FHE dissolved out of DRSI in the produced water decreases from 4.31 to 3.70 mg/L at 50—55℃ in 14—20 h. The dimension of the DRSI to be used in a production well is calculated as =8 mm and L=645 mm according to the principle of similarity. Downhole use of the DRSI in a production well at ASP-flood area leads to lowering of motor current of submerging screw pump by 4—6 A while the amount of produced liquid raised slightly.