陶粒置换泥浆法下管技术研究

采用双塞自平衡法下瓦斯抽排管时，上部空管段长度达到了300 m，管内外压力差和提管拉力共同作用，发生瘪管事故。基于此，提出了在上部工作管内用陶粒置换泥浆的下管技术。通过室内试验，测得普通陶粒的抗围压强度为2．4 MPa。当泥浆密度为1200 kg/m3时，对应陶粒放置深度200 m，并分析了普通陶粒的在围压作用下的破坏机理。现场应用表明，用陶粒置换泥浆，明显减轻钻塔负荷；减小了管内外压力差值，有效避免了套管的瘪管事故。

Research on Technology of Sinking Pipe by Method of Replacing Mud with Ceramist

In the engineering of sinking pipe by double -stopper self -balanced buoyancy method , when the length of top empty pipe reached 300 meters, under the interaction of internal and external pressure difference and tension of lifting pipe , collapse accident occurred .Based on this , a new technology in which mud is re-placed by ceramist in the upper part of the pipe was put forward .In the indoor experiment , the ceramist ’ s strength of resistance against surrounding pressure was measured to be 2.4 MPa, which responding to the depth of 200 m of ceramist placed in the mud , with the density of the mud 1 200 kg/m3 .Failure mechanism of the ce-ramist under the surrounding pressure was analyzed as well .Finally, the field application showed that replacing mud by ceramist obviously reduces the load of rig during sinking pipe and also reduces the difference of internal and external pressure , and the collapse of tube is effectively avoided .