加重剂对抗高温超高密度柴油基钻井液性能的影响

The Effects of Weight Materials on the Performance of High Temperature Ultra-high-density Diesel Oil Base Drilling Fluid

在塔里木盆地库车山前钻遇库姆格列木群盐膏地层时,要求采用抗高温超高密度油基钻井液,该钻井液必须具有良好流变性、低的高温高压滤失量、良好的封堵性与动、静沉降稳定性。研讨了不同类型加重剂对抗160℃超高密度柴油基钻井液性能的影响;采用重晶石(ρ=4.2 g/cm^3)、重晶石(ρ=4.3 g/cm^3)、氧化铁粉、Microdense等单一加重剂配制超高密度柴油基钻井液,钻井液性能无法全面满足钻井工程的需要;采用具有超微细、高密度、球形等特点的MicroMax加重的超高密度柴油基钻井液拥有非常好的流变性能和良好的沉降稳定性,但无法控制钻井液的高温高压滤失量;当重晶石和MicroMax按60∶40比例复配时,可配制出性能良好的超高密度(2.4～3.0 g/cm^3)抗高温柴油基钻井液,能满足库车山前钻进高压盐水层与易漏地层的需求。

High temperature ultra-high-density oil base drilling fluids have long been used in drilling the salt/gypsum formations of the Kumugeliemu group in Kuche piedmont area in Tarim Basin.Oil base drilling fluids used in this area should have good rheology,low HTHP filtration rate,good plugging capacity and dynamic/static settling stability.This paper discusses the effects of different weighting agents on the properties of a high temperature(160℃)ultra-high-density diesel oil base drilling fluid.The performance of an ultra-high-density diesel oil base drilling fluid formulated with single weighting agent,such as barite with density of 4.2 g/cm^3,barite with density of 4.3 g/cm^3,iron oxide powder or Microdense,cannot satisfy all the needs of drilling engineering.A weighting agent MicroMax,which is an ultra-fine,high density and spherical powder was then used to formulate the required oil base drilling fluid.The MicroMax weighted oil base drilling fluid had excellent rheology and good settling stability,the HTHP filtration rate of the drilling fluid was out of control though.Using a weighting material mixed with 60%barite and 40%MicroMax,a high temperature ultra-highdensity(2.4-3.0 g/cm^3)diesel oil base drilling fluid with good properties was formulated;it can satisfy all the needs of drilling high pressure saltwater zones and hole sections in which mud losses are easy to take place.