Development Of Oil-based Foam Drilling Fluids For Shale Gas Drilling

This thesis mainly focus on the research of oil-based foam in drilling fluid which can be used to overcome the high sensitivity to water and the large drilling fluid leaks during shale gas drilling. Through indoor experiment, oil-based blowing agent has been synthesized and its best compound blowing agent has been screened as well. With the help of these relevant analyses, oil-based blowing agent formulation was finally worked out. Due to the development of oil-based foam stabilizer, oil-based foam drilling fluid was compounded and evaluated under different conditions. At the same time, the microstructure variation of oil-based foam has been carefully observed under microscope.The specific contents and the outcome of the thesis are as follows:(1) the compound of oil-based blowing agent BMG, the optimization of reaction conditions, the evaluation of foam performance. The major reactant are C19H3892?C9H13NO? C3H6O2 and the best reaction conditions are temperature one 140?, temperature two 45?. The reaction time one is six hours and the reaction time two is three hours. The mass concentration of catalyst KOH is 0.8%. the molar ratio of the best reactant is:Methyl Stearate: N-Benzylethanolamine:glycidyl=1.0:1.2:3.0; Under normal temperature, the foam height of the mass concentration ratio 0.6%BMG in diesel oil is 200ML and its half-lives is 77s. The foam height is 190ML at 120?and its half-lives is 56s. The original surface tension of diesel oil can be cut down from 27.0mN/m to 17.5mN/m.(2) The formulation of the best oil-based blowing agent BFG is worked out through screening and compounding of the oil-based blowing agent. The best ratio is BMG: GMO=3: 1. The foam of mass concentration of 0.6%BFG can reach 260ML and its half-lives is about 105s. The comprehensive value of foam can be 20475ML. Under such conditions, the original surface tension of diesel oil can be cut down from 27.0mN/m to 16.0mN/m.(3) The manufacture of oil-based foam stabilizer HXG:its formulation is:organic soil: xanthan gum=1:3(mass concentration ratio) and the best mass concentration ratio is 2.0%. by adding this foam stabilizer, the foam height can reach 275ML and its half-lives can reach 245s. The comprehensive value of foam can be 50531mL·s.(4) The confirmation of the best oil-based foam drilling liquid formulation:diesel oil +0.6%BFG+2.0%HXG, the temperature resistance of oil-based foam drilling liquid is 120?-140?. The shale roll recovery is 96.66%. The resistance of detritus can reach 15%. By adding 15% detritus, the foam height can reach 210ML and its half-lives is 200s. The resistance of natural oil pollution is 15%. Its resistance to salt and water is more than 14000mg/Land 20%?(5) The microstructure of oil-based foam varies apparently under different conditions. Without other substance, the size of oil-based foam varies greatly in which the shape of the foam is irregular and there exists more large foams. By adding detritus, there exist more small foams and the liquid film of large foam is surrounded by many small foams which still exist in foam liquid. Detritus mainly remains in liquid film. By adding natural oil with which oil-base fluid mixed thoroughly, there exist circular small foams with smooth liquid film. When NaCl is added in, the shape of oil-based foam is mainly circular and many small bubbles exist not only on the liquid film of large foam but also in the liquid between foams. When water is added in, the shape of large oil-based foam is irregular and the shape of small foam is mainly circular. The number of tiny foam increased.