油酸酰胺型油基钻井液降黏剂作用机理

在基浆中分别添加不同类型的黏土，模拟地层土对钻井液黏度的影响，添加不同浓度的沥青降滤失剂模拟沥青对钻井液黏度的影响。结果表明，在基浆中分别添加5%有机土、15.5%沥青降滤失剂后基浆塑性黏度增加100%，动切力至少增加370%。在污染后的基浆中添加1%油酸酰胺型降黏剂后，可使混入黏土的基浆塑性黏度降低10%，动切力降低80%以上；添加15.5%沥青的基浆动切力降低73%以上，说明油酸酰胺可拆散劣质固相形成的网架结构。在南缘天安X井现场油基钻井液老浆(密度为2.25 g/cm3)中添加1%油酸酰胺型降黏剂，其塑性黏度降低15%，而动切力可降低30%以上。油酸酰胺降黏剂在油基钻井液老浆中主要作用是拆散劣质固相形成的网架结构，降黏规律与基浆中含有过量黏土和沥青污染物相关。高温高压流变测试结果表明，在205 ℃下油酸酰胺型降黏剂仍能使现场油基钻井液老浆的塑性黏度降低4.76%、屈服值降低8.70%，拆散现场浆中过量的网架结构，有效地改善了现场浆的流变性。 

Mechanisms of Oleamide as Thinner in Oil Based Drilling Fluids

In laboratory experiment, different types of clay were added to a base mud to investigate the effect of formation clays on the viscosity of the base mud, and an asphalt filter loss reducer was added to a base mud at different concentrations to investigate the effect of asphalt on the viscosity of the mud. After adding 5% organophilic clay and 15.5% asphalt filter loss reducer into the base mud, the plastic viscosity of the base mud was increased by 100%, and the yield point of the base mud was increased by at least 370%. An oleamide type thinner was then added into the base mud contaminated with organophilic clay at 1% and the viscosity of the base mud was reduced by 10%, and the yield point reduced by at least 80%. After adding 1% oleamide type thinner into the base mud treated with 15.5% asphalt, the yield point of the base mud was reduced by at least 73%. These experimental results indicate that oleamide is able to disassemble the network structure formed by the low quality solids in the mud. An oil based mud (density 2.25 g/cm3) sample was taken from a well and was treated with 1% oleamide thinner, the viscosity and yield point of the mud were reduced by 15% and at least 30%, respectively. The major role of the oleamide thinner in the oil based mud sample is to disassemble the network structure formed by the low quality solids in the mud, the mechanism of viscosity reducing is the same as that of the mud contaminated with excessive amount of organophilic clay and asphalt. Rheology test at high temperature high pressure conditions has shown that at 205 °C, oleamide can still reduce the viscosity of an old oil based mud by 4.76% and the yield point of the old oil based mud by 8.70%. The oleamide thinner disassembles the excessive network structure in the mud taken from the rig-site and effectively improves the rheology of the mud.