Selection Of High Temperature Resistant Plugging Material And Its Plugging Effect Evaluation For SK2

SK2 is located in Xujiaweizi fault depression of Songliao Basin,the depth of the well 6400 m,will be the first in the world to drill through the Cretaceous continental strata of continental scientific drilling,and provide scientific basis for the study of 65 million years ago to 140 million years the earth's greenhouse climate and environment change.During drilling,the deeper the well is,the more difficult the construction is and the more difficult it is to deal with the problem.Once the drilling leakage occurs,not only will cause a huge loss of drilling fluid,but also pose a threat to the normal drilling,therefore,in order to ensure the safety of drilling,it is necessary to pay attention to drilling leak proof.According to the geothermal gradient,the temperature of SK2 can reach above 200.The commonly used materials for plugging while drilling cannot meet the needs of the high temperature environment,and the current high temperature drilling plugging materials mainly focus on the research and development of new materials.This paper is based on the SK2 project,in order to meet the needs of high temperature drilling leak prevention and plugging,select the appropriate plugging material.Combined with the characteristics of Songliao Basin strata,lithology of multilayer section is analyzed and studied,and evaluate the developmental characteristics and influencing factors of the crack formation leakage,a comprehensive understanding of the development characteristics of SK2 leakage layer layer,provides a reference for drilling plugging.20 kinds of commonly used plugging materials were selected.Through the hot rolling test,the high temperature resistance of the material was evaluated and 9 kinds of materials with high temperature resistance of more than 200 C were selected.According to the requirements of SK2 plugging while drilling,6 kinds of plugging materials were further screened and tested with SK2 high temperature drilling fluid system.Finally,the plugging effect of single plugging agent and the effect of compound plugging are tested through the laboratory test,which provides a reference for SK2 plugging while drilling.The main research contents and results are as follows:(1)According to the stratigraphic sequence characteristics of Songliao basin.The lithology characteristics and fracture development characteristics of SK2 target layer are analyzed,and the influence of various factors on SK2 drilling loss is studied.(2)20 kinds of materials,such as walnut shell and mica slice,were selected in the usual plugging materials.The thermal resistance of the materials was evaluated by indoor hot roll test,and 9 kinds of plugging materials which could resist 200 degree high temperature were selected.(3)The drilling drilling plugging mechanism was analyzed,and according to the technical requirements of SK2 plugging while drilling,further optimized the 6 drilling plugging material economy and reliability,and the 6 kinds of materials and SK2 field using high temperature drilling fluid system compatibility test.The results show that the granular plugging material such as Calcium Carbonate Granules did not affect the basic loss of drilling fluid rheology and filtration in the amount of 5% or less,more fibrous material and sheet material quantity will have a certain impact on the rheological properties of drilling fluid,and the two types of materials of drilling fluid filtration has little effect.(4)The plugging performance of three kinds of materials,such as granular,fibrous and sheet materials,under different dosage was evaluated by DL-2 plugging test device,and the plugging effect of three kinds of composite materials was tested.The results show that the particle plugging material has a certain plugging effect on the simulated leakage layer,and the optimal addition amount is about 5%.when the fiber plugging material and the sheet plugging material are used as a single agent,there is no plugging effect on the simulated leakage layer,and it need to be used with other materials.When the three kinds of materials are used in combination,the plugging effect is obviously enhanced.Three types of composites,the plugging effect is significantly enhanced,and ultimately selected for SK2 drilling plugging agent formula of particulate material: 5% granular material+ 2% sheet material + 2% fibrous material,granular material can choose Calcium Carbonate Granules,coke grain and diatomite particles,sheet material can be selected pieces of mica fiber shaped material can choose asbestos fiber and glass fiber.