Development and Field Application of a New High Molecular Weight Hollow Micro Beads

Hollow plastic microbeads made of polystyrene previously developed are easy to agglomerate when used as a lightweight agent in field drilling fluids, and are thus easy to be bond with drilled cuttings, thereby being removed by solids control equipment and resulting in a gradual increase in mud weight. To solve these problems, efforts have been done on the modification of the body and surface of the microbeads, giving birth to high MW polymer hollow beads with a double-layer structure, SMHPS-2. WF monomer optimization and the determination of the concentrations of critical materials such as catalyst, foaming agent, surface modifier and antistat were performed in developing SMHPS-2, which were dried with spray drying. Laboratory study showed that the particles of SMHPS-2 were in round shape with smooth and dense surfaces. SMHPS-2 had particle sizes less than 100 μm, average density between 0.31 and 0.32 g/cm³, compressive strength of 50 MPa, and remained stable at 90℃. Particles of SMHPS-2 were resistant to abrading, stable in a dispersion, and did not agglomerate by themselves, and did not adhere to drilled cuttings. In field application in the well Jin-111, addition of 4% SMHPS-2 in a base fluid reduced the density of the base fluid by 0.04 g/cm³. SMHPS-2 showed good adaptability to use with the solids control equipment and superior resistance to shearing; no adhesion and agglomeration were observed during drilling.