Synthesis And Study Of Polymer - Based Water - Based Film - Forming Loss - Reducing Agent

During the drilling operations, the problem of hole collapse exists at any time, the differential pressure leads to the water loss of the drilling fluids, and the main reasons of hole collapse is the water of drilling fluids permeate through the mud shale formation near the borehole wall, so any kind of techniques and means must be taken to control the water loss of the drilling fluids, so that to prevent water going into the formation. Membrane filtration control agent is a new kind of membrane-forming agent for drilling fluids, it is usually used to form the membrance in the water-based drilling fluids, so that to reduce the water loss in drilling fluids and keep the stability of the wellbore.According to the technique of membrane water-based drilling fluid and the theory of the polymer membrane-forming agent, I have designed a kind of polymer membra ne filtration control agent. This agent should have the abilities of low molecular weig ht, high electric density and fine adsorbability, and it also should be able to form a fi ne membrance on the wall of a well, so that it can improve the ideality of the mud shale’s membrance. On the basis of these requirements, I use acrylamide, dimethyl dia llyl ammonium chloride,2-acrylamido-2-methylpropane sulphonic acid and methacrylate as monomers to polymerize in water, and get the quadripolymer which I want.This paper uses single-factor experiment to research the effect of reaction conditions to membrane filtration control agent, and gets the optimum conditions:reaction time is 30mins, reaction temperature is 50℃, monomer total concentration is 30%, monomer ratio AM: AMPS:DMDAAC:MA(mass ratio)= 70:20:12:30, initiator concentration is 0.12%. Measure the intrinsic viscosity[η]=565.27mL/g and characterize the molecular structure of polymer by infrared spectroscopy, after these tests, I verify the product meets the requirement of the designed molecular structure.During the clay dispersion experiment and anti-swelling experiment, the dispersion power of the clay is more than 70% under the effect of 5% membrane filtration control agent, and the anti-swelling power is up to 80%. And in the mud ball immersion experiment, the mud ball which is in membrane filtration control agent has formed a preservative on its face, and this preservative stop the access of water effectively, so this experiment intuitively prove the semipermeable membrane effect. the results of these experiments showed that the product can play a very important part in preventing collapsing, and this property is corresponding to the quality of improving the idealism of the semi-permeable membrane, it also can restrain mud shale’s hydration, dispersion and swelling effectively, make a great significance on preventing collapsing. I proved the existence of the mud cake’s surface film which is formed after the water loss by observing the superficial shape of membrane and scanning electron microscope experiment. Verified and evaluated the effect of polymer membrane filtration control agent’s film forming by using self-made simple device, and this experiment showed that the product can improve the ideality of clay surface, make the clay surface’s properties are more similar to the semipermeable membrane, and the product can also reduce the water loss of drilling fluid greatly by plugging the porosity of mud shale.The researches about the dissolubility, salt tolerance, compatibility of calcium, temperature resisting, and compatibility showed the product’s good performance in these aspects, and its water-solubility is better than HPAM, its compatibility is better than some drilling fluid agents which are used in site now. It also revealed a good effect on film forming and water loss control in different drilling fluids.