Research On Cement Slurry System Of Salt-gypsum Layer In A Block Of Salt Rock Gas Storage

With the change of the proportion of energy structure,the proportion of natural gas increases year by year,but the consumption of natural gas has a great peak regulation.Underground gas storage is a key facility for peak regulation of natural gas consumption.According to the strata where the gas storage is located,the gas storage can be divided into four types:depleted oil and gas storage,aquifer gas storage,salt cavern gas storage and abandoned mine gas storage.The salt rock gas storage in a block studied in this paper is a depleted oil and gas storage gas storage.The salt paste layer is the cap layer of the reservoir.In the process of sealing and cementing the salt paste layer,there are two difficulties:（1）Under the condition of high salt solution,the conventional water loss reducing agent has poor salt resistance,so it is difficult to effectively control the water loss of cement slurry;（2）Cement stone brittleness,poor deformation ability,pressure changes in casing easy to form a micro-annulus,resulting in cement ring isolation failure.Therefore,to develop a salt-resistant elastic ductile cement slurry system which can be used in salt gas storage is the key to solve the problem of cementing salt-paste layer in salt gas storage.By aqueous solution polymerization method,four kinds of monomer AMPS,DMAA,AM,MA,the ratio of monomer,reaction temperature,monomer,initiator content,such as single factor experiment was carried out,and after viscosity method of research,finally salt-resistant water loss additive ADAM-J showing the motion of the optimum synthesis conditions,the water loss additive resists salt to saturation,add 2%water loss can be controlled within 24m L·（30 min）^-1.The water loss additive can reduce the water loss through the combined action of increasing the filtrate viscosity,forming a flexible elastic adsorption layer by adsorption and blocking the pore of mud cake.In order to solve the problem of poor hydrophilicity on the surface of rubber powder,the surface of rubber powder was modified by sodium silicate,and the existing modification process was improved.The optimal process was that the rubber particles were wetting in 2.50molded sodium silicate and then heated and cured at 70℃for 0.83 h.The modification time and cost are greatly shortened.Adding modified rubber powder into cement slurry can greatly reduce the loss of compressive strength of cement stone.Based on the salt-resistant water loss reducing agent and modified rubber powder,the salt-resistant elastic ductile cement slurry system was constructed.The system has low filtration,good liquidity,low elastic modulus and thickening time under control,in addition,the salt resistant ductile slurry system of the site into the well working fluid compatibility is good,in the process of cementing,salt elastic resistance slurry system under the condition of salt bath to keep good performance,and improved the first and second interface shear bond strength,and has good under alternating load and elastic deformation ability.