Synthesis And Performance Research Of Oil Well Cement Latex Toughener

The development process of oil can be divided into exploration, mining,transportation and processing. Well cementating is the most important link in theprocess of drilling, cementing quality is directly related to continue drilling,completion and other follow-up work. With the sustained and rapid development ofChina’s oil technology, the situation of cementing operation is more and morecomplex, useing large scale enhanced recovery measures, perforating and fracturingput forward higher requirements of mechanical properties and thermal properties ofoil cement. Adding admixture to cement to improve the performance of oil wellcement is a key technology of cementing. In this paper, by using molecular designprinciples, oil well cement latex toughener OWCL-1G which is used in lowtemperature and oil well cement latex toughening OWCL-2G which is used in hightemperatures were synthesized.Using styrene (ST) and butyl acrylate (BA) as the main polymerizable monomers,a cement latex toughener, OWCL-1G, used in oil wells was synthesized and itsdifferent physical and chemical properties were evaluated. OWCL-1G was preparedby the soap-free emulsion polymerization. A reactive emulsifier,2-acrylamido-2-methyl propane sulfonic acid (AMPS), was added to prevent theresidual emulsifier absorbing water in traditional emulsion polymerization, therebyavoiding swelling, softening and losing strength of cement. Characterize the structureof the copolymer by using IR and TEM, the results show that synthetic polymersachieve the desired design goals. Some properties were tested, such asthermogravimetric analysis (TG), salt resistance and freeze-thaw stability. The resultsshowed that: OWCL-1G has good heat resistance and the decomposition temperatureis at260℃, it can keep stabilization in saturated salt water and it has goodfreeze-thaw stability. By examining the API fluid loss and free water, OWCL-1G wasobserved to have the capability to control water loss and it has no free water. Thegrouts with low filtration could be obtained by the compatibility between OWCL-1Gand filtrate reducers. Experimental results of compressive and flexural strengthshowed that the flexural strength of hardened cement paste has significantly increased,suggesting that OWCL-1Gcan effectively improve the cement toughness. Scanning electron micrographs (SEM) revealed that the latex particles could provide thefloss-like linking in numerous small cracks of cement, but no linking occurred in thehydration products of pure cement.Using polybutadiene latex (PBL) as the main chain, styrene (ST) and AMPS asgrafting monomer, oil well cement latex toughener OWCL-2G was synthesized byemulsion grafting polymerization. It can improve the defect of butyl benzene latexsuch as badly salt resistant, badly freeze-thaw stability and poorly cementationstrength. Investigate various factors which influence the graft rate, obtained the besttechnic of high grafting rate. The structure of copolymer was characterized by usingTEM. And fluid loss, free water, salt resistence, freeze-thaw stability and thickeningperformance are evaluated. The results demonstrate that slurry with OWCL-2G hasproperties of low fluid loss, no free liquid, salt-resistance, good freeze-thaw stabilityand the thickening curve emerged right angle with short transition period.Characterize hardened cement pastes which contained OWCL-2G, the results showsthat a crosslinked structure which build up with latex particles and cement particles isformed, thus improve the flexural strength of hardened cement paste.