Cementing Cementing Fiber And Particle Material Plugging And Toughening Experimental Research

Cementing is the key part for the drilling engineering and completion engineering, it is also the crucial assurance for the continued security, drilling and oil and gas extraction. However, lost circulation when falling back easily happens in the pore-type low pressure formation, absorbent formation and induced crack formation when cementing, so conventional cement slurry for low density is hard to meet the requirements of annulus isolation. In other way, cement paste is hard brittle material, both the hydraulic variation caused by pressure test, acid fracture, fracturing and the mechanical stress caused by drilling stem collision and perforation are possibly demolish the mechanical integrity and hydraulic impermeability of cement paste, and lead to failure of zonal isolation. Fiber and elastic particulate materials have both merits and faults to the well cement slurry, they can enhance the plugging ability of cement slurry in different ways, and increase cement paste's tenacity.In this paper, ceramic fiber, polypropylene fiber, fiber SD-66, steel fiber and elastic particulate materials were used, and a stable cement plugging system were obtained by the assorted conditioner. The fiber and elastic particulate material cement system's plugging effect were reviewed by plugging ability assessment device, and analyzed plugging mechanism based on the experimentation. In addition, investigated the cement paste's toughening mechanism, researched the effects of dosage of aluminum silicate ceramic, carbon fiber, steel fiber and rubber powder impacts on the fluidity of cement slurry fluidity, the compressive strength and breaking strength of cement paste, and via a orthogonal test to surveyed the influence rules of cement paste's compressive strength and breaking strength caused by the different addition amount of rubber powder and inorganic fiber, the different addition amount of rubber powder and steel fiber.The results show that:(1) The sealing mechanism of single fiber-plugging materials.such as fiber, ceramic fiber, fiber SD-66 and carbon fiber and elastic particle materials such as rubber powder particle,by the indoor experiments.(2) Single elastic particle materials are hardly sealing the formation, nevertheless the single fiber-plugging materials have some plugging effects. To obtain good sealing effects, it is recommended fiber and granular materials after combinationg, it is better to use both fibers and particle materials. The sealing mechanism of both fibers and rubber powder is explained by the indoor experiments.(3) In order to improve the folding strength and ductility of cement paste, single toughening materials including ceramic fiber, carbon fiber, steel fiber and rubber powder have an optimal added amount. The optimal added amounts are 0.06%,0.18%,2-4%,3% respectively;meanwhile,by the analysis of toughening mechamism also found that the fiber cement or rubber on the bending strength greater than the compressive strength.(4) When the ratio of fiber and rubber powder is 3.0% rubber powder+1.5% SD-66 fiber, 3.0% rubber powder+1.5% metal fiber, the effect of improving the ductility of the cement paste is very good.