Research And Application Of Cementing Ultra-high Temperature Cement Slurry System

As the oil and gas exploration and development goes to deeper commands of drilling depth, the higher temperature creates difficulties to drilling and completion work. By Halliburton definitions about high temperature cementing job is under formation temperature more than 150? and furthermore the ultra-high temperature cementing goes to more than 180?, which creates high requirements for cement slurry on thickening time, stability and top strength. For complex geological condition challenges, special slurry systems such as high density slurry, low-density slurry, and brine slurry are widely used. The study is based on domestic high/ultra-high temperature cementing requirements, develops an ultra-high temperature cement slurry system.This study synthesized polymer fluid loss additive product HT-1 and polymer retarder product HT-2, found their performance under ultra-high temperature condition. HT-1 has a good performance in temperature resistance (4?6% dosage in Saturated brine slurry API fluid loss less than 100mL) and fluid loss (4?6% dosage in conventional slurry API fluid loss less than 50mL). HT-2 has the advantage of wide application temperature range(60?200?) and excellent temperature resistance(the thickening time of saturated brine cement slurry was just slightly extended compared with same dosage in fresh water cement slurry system).Mainly based on the above products, combined with strength stabilizer, filler, suspending agent, a ultra-high slurry system was developed. Due to The overall performance of Ultra-high temperature high density cement slurry, Ultra-high temperature low-density cement slurry, Ultra-high tempera on-site condition requirements, we test the performance of this system under various condition such as different density, brine and anti-gas channeling, the results shows the slurry system is easy adjustable with thickening time, insensitive with temperature/density change and superior stability.Also by combined with specific additive the plasticity of cement stone can be up to adjustable with different well cementing requirements. Mating spacer system is used to solve the drilling fluid pollution problem.With the successfully application on NB 3-81 well liner cementing operation, CBL results showed the logging cementing quality after 48h WOC achieved excellent. Well conditions with BHST exceeds 240? and BHCT range from 180? to 190?. Main challenges during operation such as high bottom temperature, large temperature difference, high risk gas migration and narrow pressure window. The huge success shows the superior on-site application and performance of the cement slurry system which also indicates a good market application perspective.