低粘切高密度油基钻井液体系

目前国内对深层页岩气的开发力度越来越大,对高密度、超高密度的钻井液需求愈发明显,由于油基钻井液具有抑制性强、抗高温、润滑性好等优势,在页岩气钻探中占有重要的地位。本文通过研制的主乳化剂EMUL-2及辅乳化剂COAT-2构建低切力高密度、超高密度柴油基钻井液,来满足深井超深井的钻井使用。实验数据表明,在高密度2.20 g/cm³、2.40 g/cm³的情况下,通过实验优选,所构建体系性能良好,粘切低、破乳电压>400 V、高温高压滤失量<5 mL；且抗老浆污染能力强,在混入50%的老浆后,粘度及切 力提升、破乳电压增长至800 V以上、高温高压滤失量<5 mL,具备现场使用前景。加重到超高密度后,2.60 g/cm³、2.65 g/cm³时,通过调整配方加量,依旧可以得到低粘切、破乳电压>700 V、高温高压滤失量<5 mL的油基钻井液体系,但是已无法混合老浆使用；且通过实验数据对比,该种类乳化剂性能远优于其他种类乳化剂；加重到2.70 g/cm³时,体系粘度过大。

Low viscosity and high density oil-based drilling fluid system

At present, the development of deep shale gas in China is increasing, and the demand for high-density and ultra-high-density drilling fluids is becoming more and more obvious. Because oil-based drilling fluids have the advantages of strong inhibition, high temperature resistance, and good lubricity, it occupies an important position in shale gas drilling. In this paper, the main emulsifier EMUL-2 and the auxiliary emulsifier COAT-2 are developed to construct a low-shear, high-density, ultra-high-density diesel-based drilling fluid to meet the needs of deep and ultra-deep wells. Experimental data shows that under the conditions of high density 2.20 g/cm³ and 2.40 g/cm³, the system is optimized through experiments and has good performance, low viscosity-cutting, demulsification voltage>400V, high-temperature and high-pressure filtration loss <5mL; The old pulp has strong pollution ability. After mixing 50% of the old pulp, the viscosity and shear force will increase, the demulsification voltage will increase to more than 800 V, and the high temperature and high pressure filter loss will be less than 5mL, which has the prospect of on-site use. After weighting to ultra-high density, at 2.60 g/cm³,2.65 g/cm³, by adjusting the dosage, an oil-based drilling fluid system with low viscosity cutting, demulsification voltage>700 V, high temperature and high pressure filtration loss <5 mL can still be obtained, But it can no longer be mixed with old pulp; and through the comparison of experimental data, the performance of this type of emulsifier is far better than other types of emulsifiers; when the weight is increased to 2.70 g/cm³, the system viscosity will be large.