Study And Application On Improving Cementing Quality Of High Pressure Gas Wells In Western Of Sichuan

The regular production and stimulation of oil and gas wells are usually determined by the cementing quality,which would even affect the whole life of oil and gas wells.Because of the complex geological characteristics and engineering factors,the cementing quality is usually poor in Western Sichuan area.Therefore,improving the cementing quality in this area has become an urgent problem.Firstly,the influencing factors of cementing quality in this area are analyzed.Secondly,the measures to improve the flushing rate and displacement efficiency are proposed by experimental.Then high density cement system slurries were developed to prevent gas channeling.Finally,the research results are applied to the actual construction work on site.The main research results are as follows:Jianmenguan Formation belongs to argillaceous siltstone formation,so the cementing quality is the worst.The optimum drilling fluid performance is 6-7Pa initial shear force,11-13Pa final shear force,5-11 Pa dynamic shear force and 52s funnel viscosity.When the flushing contact time is more than 4 minutes,the fluidity of cement slurry is 20-25 cm,the water loss is less than 50 mL,the thickening time of collar slurry and tail slurry is 30-70 min,and the annular velocity is between 0.8-1.0 m/s,the cementing quality is the best.The efficiency of cuttings removal is positively correlated with annular discharge,negatively correlated with casing eccentricity and flushing fluid viscosity.The farther the distance between cyclone centralizer and cuttings bed is,the lower the flushing efficiency is.The combination of fibre flushing fluid and cyclone centralizer can achieve better flushing effect at low discharge.Three kinds of anti-channeling high density cement system slurries with density of 2.00g/cm3,2.20g/cm3 and 2.40g/cm3.The methods of improving displacement efficiency,flushing efficiency and anti-channeling high density cement slurries proposed in the paper were appliced in field cementing.Good results have been achieved in improving cementing quality in this area.This proves that the measures proposed in this paper to improve the cementing quality in Western Sichuan have important engineering significance for improving the cementing quality in this area.