Research Of Preparation And Property Of Efficiency Pressure-bearing Smart Lost Circulation Composite Materials

The success rate of plugging and drilling directly depends on the performance of lost circulation material. The traditional lost circulation materials can not effectively plug crack due to low strength, small flow resistance in the cracks. The research and development of smart lost circulation materials will be one of effective ways to solve the problem. The model of smart lost circulation materials was designed and the shape memory alloy of the lost circulation materials was heated treatment. Then get the reasonable heat treatment process. The different preparation process was researched, and the different performances of lost circulation materials were prepared. The performance of the lost circulation material was tested.The shape memory effect has been studied through the change of recovery rate. The experiment results showed that the recovery rate of SMA improved with the increasing of the quenching temperature when the quenching medium is cold water. The value of recovery rate is maximum when the heat treatment temperature is 500 centigrade. When the treatment temperature exceed 500 centigrade, the recovery rate of SMA decreased with increasing heat treatment temperature. The recovery rate of SMA decreases with increasing holding time. The optimal heat treatment process is that the heat treatment temperature is 500 centigrade, the holding time is 10 minutes, the quenching medium is cold water.The diameter and thread pitch of the spring were determined through studying the elongation of the spring. The results showed that the elogation is 99.2%, when the diameter of spring is 1.4mm, the thread pitch is 2.5mm. The elogation is 100%, when the diameter of spring is 1.6mm, the thread pitch is 2.0mm.Different properties of smart lost circulation materials were prepared through studying the different process. The results showed that the preparation method of filling bentonite smart lost circulation materials is filling bentonite with water into spring, then spraying agglomerant onto the spring and rolling agglomeration in the cement. Bentonite was added at 5%, 10%, 15%, 20% of sodium carbonate. The particle size of smart lost circulation materials is 2.8-3.1mm. The preparation method of filling water-absorbent resin smart lost circulation materials is to fill the water-absorbent resin with 1% of expansion rate into the spring, then spraying agglomerant onto the spring and rolling agglomeration in the cement. Finally, the balls were cured with 2.5% sodium carbonate solution or 11.76% aluminum sulfate solution. The granulation rates are both 95%. After the paraffin dissolved in carbon tetrachloride, then spray it on the complex. The rate of making ball is 93%. Fill the water-absorbent resin with 1% of expansion rate into the spring, placing 30 minutes at room temperature and the balls were cured with 2.5% sodium carbonate solution or 11.76% aluminum sulfate solution. The rate of making ball is 97%. The water-absorbent resin were made into 0.2mm particle size, the mixed bentonite and polyethylene glycol 400 were filled into spring. Finally, the balls were cured with 2.5% sodium carbonate solution or 11.76% aluminum sulfate solution. The granulation rates are both 94%.The performance of prepared smart lost circulation materials was tested. The results showed that the lost circulation materials have certain strength, put that into the status of 60 shift/s, the lost circulation materials with good dispersion and can not be broken. Plugging 2mm and 4mm cracks, when the content of lost circulation is 8% and in which filled with bentonite smart lost circulation materials, the bearing pressure were separately 7.9 or 7.1 times than that without smart lost circulation materials, the bearing pressure of 80 centigrade were respectively 8.9 or 8.2 times than that of at room temperature. When the content of lost circulation is 12% and in which filled with bentonite smart lost circulation materials, the bearing pressure were separately 8.4 or 7.5 times than that without smart lost circulation materials, the bearing pressure of 80 centigrade were respectively 8.1 or 6.8 times than that at room temperature.