Foam Flushing Fluid System And Its Performance Evaluation

Cleaning the hole with the foam fluid is a newly-developed technique in recent years which primarily solves the problem of severe reservoir pollution in low presser and leaking well. In the dissertation, systematic theory research and laboratory study is conducted to try to solve the kernel problem of foam hole-cleaning treatment: how to enhance the foam stability. Based on the relative theory study of foam both here and abroad and large amount of tests in lab, we develop ZX-1, a new set of foam cleaning fluid system.The properties of foam fluid, such as the viscosity of the adsorbed film, gaseous transmissibility and so on, are analyzed systemically based on numbers of literatures. Withal surfactant theory for base, experiments are carried out to examine the foam property of four surfactant solution, making certain that the formability of anionic surfactant sodium dodecyl sulfate solution and its foam property is of the best. Through the binary match test of anion surfactant/anion surfactant, anion surfactant/cation surfactant and anion surfactant/non-ionic surfactant, we confirm that, as the binary match foamer, lauxyl sodium sulfate/sodium dodecyl benzene sulfonate system is beneficial to the foam property. Measured lauryl alcohol's influence on the foamability of anion surfactant, cation surfactant and non-ionic surfactant solution, we find that lauryl alcohol can greatly enhance the foam stability of lauryl sodium sulfate solution, while the add of lauryl alcohol make no difference to that of ABS, OP-10, HTAB solution. On the precondition of certain latherability, through the test of foam surface viscosity, we screen out HPAM/HEC as the right foam stabilizer. The best composition of ZX-1 foam washing fluid system is determined: SDS4g/l+ABS0.5g/l+lauryl alcohol0.2g/l+HEClg/l+HPAM0.2g/l. Said system, with its low cost, good foamability, has a foam half time of 40 minutes under room temperature 15 degree centigrade, meanwhile its also a green operating fluid in oil and gas field. Foamed fluid macro rheological test confirms that it is a pseudoplasticity power-law fluid while the microscopic rheological test shows that the foamed fluid has good viscoelasticity. The checkout of the ZX-1 foamed fluid property, such as salt tolerance, temperature tolerance, acid and alkaline resistance, causticity, the ability to restrain shale swelling, biodegradability, toxicity of ZX-1 system and so on, show that performance in all directions of said foam cleaning fluid system can meet the require of cleaning the hole.Use AlCl₃ to instant crosslink partial hydrolysis polyacrylamide, the tests show that the crosslinking time, strength of Al³⁺and the existance of electrolyte hardly have any apparent influence on the viscosity of partial hydrolysis polyacrylamide solution of various density.