Study On The Newly Drilling Fluid Technology For Lost Circulation Prevention And Control

Super Absorbsent Polymer, as a new kind of lost circulation materials, has advantages of volume expansion after hygroscope and elastic plastic deformation ability and been focused on more and more attention recently. The sealing ability evaluation of five kinds of bridging materials common used in inland oil field is carried out firstly. Then a method for measuring the volume expansion multiple of Super Absorbsent Polymer mixed with water and a kind of facilities for measuring anti-extruding strength of gelation were developed for evaluating the performance of Super Absorbsent Polymer mainly. Three kinds of lost circulation materials products composed of Super Absorbsent Polymer SAP-1、SAP-2 and SAP-3 have been prepared through aqueous solution polymerization with AA, AM, AMS&DDC as monomer, ammonium sulfate as a initiator, MA as a crosslinker and polysaccharose polymer, bentonite and fiber as proppants. The optimum formula was confirmed through orthogonal experimental design and single factor analysis experiment on the base of main target gelation strength and assistant guideline volume expansion multiple. The gelation strength of them is higher than other products of same kinds from outland and inland and the delaying expansion regulation is more reasonable.The molecular structures of three kind Super Absorbsent Polymer products were characterized through IR spectroscopy and thermostability was evaluated. The effect of temperature and electrolyte on volume expansion regulation has been investigated, compatibility experiment of these three kind Super Absorbsent Polymer sealing products in drilling fluid and sealing while drilling experiment were performed. According to relevant sealing ultimate principle, the drilling fluid formula for sealing leakage was designed. Results of simulation experiment show that volume expansion particles have stronger elastic and plastic modification and extruding filling bridging action, combined with the common bridging materials the sealing efficiency on big gap and split serious lost circulation formation can be enhanced.