Research On High Temperature And High Density Drilling Fluid

Compared to conventional drilling, there are higher requirements for deep well drillingfluid, especially the resistance to high temperatures, which is the most important and basicperformance for deep well drilling fluid. Therefore, the temperature resistance as well as thefiltration and flow variability under high temperature are difficult to control for deep andultra-deep drilling technologies. With the increase of depth and the formation pressure,drilling fluid must have a high density to balance the high formation pressure,but it will resultin a high level of solid phase. In this case, the differential pressure sticking, lost circulation,blowouts and other complex underground accidents will be much more likely to happen.Therefore,the maintainance of the good rheology and low fluid loss of the drillingfluid willbe more difficult.This paper carried out a research on high temperature and high density drilling fluid fordeep wells in Jiuquan Basin, Yumen Oilfield. The content of clay mineral in formation K1Xand K1C is high , but most of the rocks are weakly dispersed and expansive. Therefore,tostrengthen the sealing capacity and improve the inhibition of drilling fluid is an effective wayto prevent collision. The content of clay is the key to controlling the fluid viscosity and shearforce of drilling fluid, and attention must be paid to it for high temperature and high densitydrilling fluid. The formulation of treating chemical for high temperature drilling fluid wasoptimized by experiments and the law how the treating chemical affect the performance ofdrilling fluid was studied.The amount of the treating chemical compound was initiallyidentified by orthogonal tests, and finally the formulation of the high temperature highdensity drilling fluid with a set of density 2.4g/cm³ and anti-temperature performance up to180℃high temperature was developed.The formulation is: water +2% swelling Soil+0.2%Na₂CO₃+5%SMP-2 +4.5% anti-blocking agent collapse FF+4%SPNH+0.5% DSP-2+5%liquid fluid loss additive+1% AP-1 + barite. The rheological performance of drilling fluidis good,and the filtration in junior and senior pressure was small. At the same time, it has a good sedimentation stability and properties to resist the pollution of salt paste and soil ,andthe anti-collapse properties are good.The core recovery rate of penetration is high, whichindicates the good reservoir protection properties. The preparation process is simple and theproperties are easy to maintain.