Research On Plugging Drilling Fluid For Fracture Lost Circulation Zone

The research and application of new fractured plugging material has been the key technology to improve the success rate of crack plugging.Due to the common use of bridge plug plugging materials,conventional plug plugging materials,such as calcium carbonate and walnut shell,are closely related to the opening of the leaky cracks,the retention of particles in the cracks is difficult and the stability is closely related,and the effect of the plugging is often not good.In this paper,a kind of reticulated foam plugging material was developed and developed.The experimental research on the leak stoppage was carried out in combination with the rigid calcite particles and the plugging material SQD-98.It provides a new technical reference for the leak blocking drilling fluid.In this paper,based on the formation and instability mechanism of fractured leaky plugging layer,the requirements for the plugging material are clarified,and the commonly used plug plugging materials are selected and evaluated.The synthesis and preparation methods of a reticulated foam material are proposed and studied,and three mesh size reticulated foam materials are prepared.And its performance is evaluated.Through the use of high temperature and high pressure static and dynamic plugging apparatus and four specifications of long crack module,the reticular foam material is studied and analyzed separately.At the same time,the formula of other types of plugging material is evaluated,and the leakage effect of the reticulated foam material is compared and analyzed.Based on the experimental results,the mechanism of reticulated foams is revealed.The polyurethane reticulated foam has the characteristics of small density,easy to deform,insoluble in acid,the tensile strength of diesel soak and high temperature is worse,and the grid can be filled with rigid particles.Through the use of high temperature and high pressure static and dynamic plugging test apparatus for long crack plugging,it is thought that it is difficult to plug the cracks successfully by using the reticulated foam material alone.It needs to be used with calcite particles and SQD-98 in order to achieve good leakage blocking effect.The effect of reticulated foams is better than that of fibers and rubber particles in sealing cracks.Mesh sizes of reticulated foam materials are better than single use.And the optimal plugging formula under various crack specifications is selected.The research shows that the reticulated foam material itself is similar to the elastic particle plugging material,and it can be twisted into the cracks and rigid particles together to bridge.It is easy to be compressed by bridging particles,and is tightly attached to the wall of cracks,which makes the leakage channel narrow and acts as a piece of plugging material.The reticular foam is easily retained in the narrow leakage channel,and the flow of other granular materials to the depth of the crack is blocked and accumulated here,thus promoting the formation of the plugging layer.At the same time,the granular material matching the pore size can be enveloped in the mesh,which improves the anti shearing ability of the plugging layer.While the solid particles are stacked,the water in the slurry can still pass through the reticulated foam,resulting in the loss of water,the concentration of solid phase and the rapid water loss and dense blocking layer.In the process of actual plugging,a variety of mechanisms play a coordinating role.The particle size,pore size and addition of the reticular foam have different effects on the mechanism of the foam.