1) bentonite CMC drilling fluid: 6% ~ 8% bentonite +0.4% Na2CO3+0.2% ~ 0.4% CMC (medium).
Maintenance requirements: Prepare bentonite slurry according to design requirements, fully pre-hydrate for 24h, and add CMC (medium) before spudding and stir evenly; Add drilling fluid treatment agent according to the design requirements, and use low-density drilling fluid as much as possible to prevent the occurrence of lost circulation on the premise of ensuring wellbore stability; During normal drilling, the maintenance of drilling fluid is mainly based on hydrated Sakamoto slurry and CMC glue, and mud or treatment agent should be replenished in time; Ensure that the solid control equipment works normally and is used correctly (Cha Jinyong et al., 20 10).
2) Gas drilling.
(2) Open for the second time
Polymer drilling fluid: 4% bentonite+0.2% Na2CO3+0.1%~ 0.2% NaOH+0.1%~ 0.2% FA-367+0.3% ~ 0.4% CMC (medium)+0.3% ~ 0.4%.
Maintenance requirements: NPAN is used to adjust the rheology during drilling, CMC (medium) is used to reduce the filtration of drilling fluid, improve the quality of filter cake, enhance the permeability of filter cake and the shielding wall-building ability of drilling fluid, prevent borehole wall collapse, and add low fluorescence lubricant to improve the lubricity of drilling fluid. In order to ensure the good operation of the four-stage solid control equipment, it is required that the operation rate of vibrating screen (mesh size is 60 ~ 80 mesh) is 100%, the operation efficiency of desliming device is 80%, and the effective operation rate of centrifuge should meet the relevant performance requirements of drilling fluid to ensure "purification" and "optimization" (Cha et al., 20 10).
(3) Reservoir
Potassium chloride polysulfonate drilling fluid: 4% bentonite+0.2% Na2CO3+0.1%~ 0.2% NaOH+0.1%~ 0.2% FA-367+0.5% ~ 0.6% JT888+0.3% ~ 0.4%.
Maintenance requirements: During drilling, NPAN is used to adjust the rheology, JT888 and CMC (middle) are used to reduce the filtration of drilling fluid, SMP 1 (powder) and sulfonated asphalt (powder) are used to improve the quality of filter cake, enhance the permeability of filter cake and the shielding wall-building ability of drilling fluid, prevent borehole collapse, and add low fluorescence lubricant to improve the lubricity of drilling fluid. In order to ensure the good operation of the four-stage solid control equipment, it is required that the operation rate of vibrating screen (60 ~ 80 mesh screen) is 100% and the operation time rate of desliming device is 80% during drilling, and the effective operation rate of centrifuge should meet the relevant performance requirements of drilling fluid to ensure "purification" and "optimization". Take the field drilling fluid at any time, test the permeability recovery value with the field reservoir core, and supervise whether the drilling crew adds the reservoir protective agent as required (Cha et al., 20 10).