Study On The Mechanism Of Leakage And Prevention Of Leakage And Leakage In Turkmenistan

Well leakage accidents are common in drilling,it causes huge economic losses in the global oil industry every year.Study on mechanism of leak and plugging measures could maximize the quality of drilling and overcome hidden dangers. It has a very important practical significance for improving the level of drilling technology.Regarding carbonate formations of Galkynysh gas field in Turkmenistan as research subjects,this paper analyzed the geological structure features,counted vicious leakage data,established a loss circulation formation position calculating model, and analyzed the mechanism of malignant formation leakage.The natural fractures,extended fractures one-dimensional radial model of drilling fluid loss were improved,and the drilling fluid leakage characteristics of fractured formation was analyzed.Besides,this paper also proposed plugging leakage method of malignant formations, and carried out indoor experiments of plugging.This paper established a loss circulation formation position calculating model.A riser pipe pressure method was used to determine leakage horizon.A software was written to facilitate the calculation.Combined with field data,using the software to calculated dropout horizon.and the results showed that the method of has a high accuracy.All of the calculated loss well was within 50m error range compared with actual horizon.This paper clarified the mechanism of drilling fluid loss in fractured formations.lt analyzed the three necessary conditions for loss of drilling fluid occurred,and summarized the pressure model of natural fractures loss,fracturing extended loss and fracturing leakage loss.Select The model of natural fractures loss was selected to calculate the pressure leakage pressure of the area.The model was proved as applicability by site data.Based on the basic theory of non-Newtonian fluid.a natural fracture leakage model was established.Using finite difference methods to solve the model,the results show that drilling fluid parameters, slit width and other factors are all have influence on leakage.The crack propagation model was established on the basis of natural fracture model,and analyzed the fluid pressure distribution within the fracture and the law of leakage rate.It provides the basis of optimizing plugging measures and the selection of plugging material.Based on the basic theory of non-Newtonian fluid,the natural fractures,extended fractures one-dimensional radial model of drilling fluid loss were improved.The results show that drilling fluid parameters, slit width and other factors are all have influence on leakage.As the increase of fracture width and the pressure difference,the leakage rate increased.With the increase of flow index, consistency coefficient and dynamic shear force,the leakage rate declined.Adjusting the performance parameters of the drilling fluid can reduce the leakage rate and cumulative Leakage amount in a certain degree,and provides a theoretical basis of plugging material size selection.The plugging method was proposed for the fracture-cave formation in Galkynysh. Analyzing the mechanism of lost circulation material and the method of improving the bearing capacity of the formation.It comes to a conclusion that changing the mechanical state of the wall and block cracks effectively could increase bearing capacity of the formation.Indoor experimental study was carried out and a method of sealing that mixing bridge plugging materials and HHH material was proposed,and carrying it out on-site application.The method of combining gel ZND with slurry cement was proposed to plug fracture-cave malignant Leakage formations,and it has achieved good results on drilling site.