Challenges and Countermeasures of Well Cementing Operations for Horizontal Wells in the Jinghe Oilfield

With low pressure bearing capacity of the formation,the Jinghe Oilfield is characterized by the poor quality of cementing operations in horizontal wells because cement slurry is susceptible to lost circulation.With consideration to the challenges in cementing operations,a GSJ cement slurry system was developed and optimized through lab tests and field applications.Based on formation pressures and fracturing pressures,the annular structure of slurry was determined,wherein the types and positions of centralizers were optimized.In addition,prolonged rubber plugs,resin wheel rigid swirl centralizer and shut-in valves were adopted.Laboratory tests and field applications showed the innovative GSJ cement slurry system had outstanding performances with an API loss of tail slurry of less than 20 mL,a transition time of 15 minutes,and 12h compressive strength of set cement up to 19 MPa.At the same time,software simulation results show that casing center degree is greater than 72.49%.The"turbulent flow+slug flow"compound displacement technology was adopted to minimize the risk of lost circulation.The cementing technology was applied in 18 horizontal wells in the Jinghe Oilfield.With all the cement slurry returned to the ground,all cementing operations were performed successfully.Field application results showed the cementing technology could effectively solve problems in cementing operations of horizontal wells in Jinghe Oilfield.In addition to enhance cementing quality,the innovative cementing technology could provide high-quality wellbores for fracturing operations in later staged fracturing.