Preparation And Performance Of MEG GEL Based On Cellulose For Subsea Spool&Jumper Pipelines

Influenced by the international political,economic,diplomatic and military risks,it is more difficult to develop onshore oil & gas resources.International oil companies have taken the exploitation of offshore oil and gas resources as one of their important strategies.The spool & jumper pipeline is used to connect the wellhead,christmas tree,PLEM and PLET in the subsea oil & gas production system.In order to prevent natural gas hydrate from blocking the spool & jumper pipeline under the high pressure and low temperature environment in the deep-sea,the common process of foreign oil companies is to prepare MEG gel for injection in advance.As the core technology of deep-sea oil pipeline operation,this technology has been monopolized by a few foreign companies.In this paper,cellulose based subsea MEG gel was prepared by using cellulose as thickener and organic aluminum as the crosslinking agent.It laid the foundation for the subsequent application of MEG gel injection technology in the development of deep-sea oil & gas resources in the South China Sea.The main research contents are as follows:(1)Low molecular weight hydroxyethyl cellulose(HEC)and carboxymethyl cellulose(CMC)were prepared by acid degradation method.The effect of acid degradation on the intrinsic viscosity and viscosity average molecular weight of the HEC and CMC was investigated,respectively.The dissolution process of the two kinds of cellulose was analyzed by polarizing microscope.The swelling performance of the two kinds of cellulose solutions was tested.Effect of solution temperature,cellulose concentration,p H value,salt ion concentration and shear rate on the apparent viscosity of the system is investigated.(2)The process of cross-linking of HEC and CMC with organic aluminum crosslinking agent was investigated.The effects of cellulose concentration,organic aluminum crosslinking agent and p H value on the properties of the gel system were studied.The best formulation and process conditions were obtained.The best process formula was obtained when the thickener was 1wt%,the crosslinking agent was 4wt%,and the antifreeze liquid was 40wt%.The apparent morphology,swelling/deswelling tendency,rheological properties,stability,frost resistance and compressive strength of the gel were studied.Through comparison and optimization,HEC was chosen as thickener for MEG gel of subsea spool & jumper pipeline and the best formula was determined.(3)Based on the results of laboratory tests,a pilot scale test of cellulose based MEG gel injection technology was carried out.Design of process conditions for cellulose based MEG gel,including formulation composition,production equipment and operation process was obtained.The feasibility of the experimental formula,injection process and equipment was verified.Through the practice of engineering application,experience has been gained in MEG gel injection process for subsea spool& jumper pipeline.