METHOD FOR MAKE-UP OF REVERSIVE-INVERTED DRILLING FLUID BY PHASE INVERSION Russian patent published in 2014 - IPC C09K8/36 C09K8/35 

FIELD: oil and gas industry.

SUBSTANCE: method for make-up of reversive-inverted drilling fluid by phase inversion includes make-up of drilling fluid with its subsequent reversive inversion under external factors by phase inversion, at that at first invert-emulsion drilling fluid (IEDF) is made that represents water-in-oil emulsion. Under influence of external factors phase inversion is made and drilling fluid is converted to oil-in-water type with subsequent reversive inversion of phases that leads to production of reversive-inverted drilling fluid (RIDF) that represents invert emulsion of water-in-oil type. In order to receive IEDF representing oil-in-water emulsion by phase inversion inverter of the 1^st type is used as an external factor with value of hydrophilic-lipophilic balance equal to 11-13 and content of the following components by wt %: neonol AF_9-4 5.0-20.0; neonol AF_9-12 9.0-30.0; oxyethyl cellulose Reocel B 0.1-2.0; fresh or mineralised water for remaining part at the following ratio by wt %; inverter of the 1^st type - 1-10; remaining part - IEDF up to 100. In order to perform reversive inversion of phases for obtained drilling fluid representing oil-in-water emulsion; in RIDF inverter of the 2^nd type is used as external factor with value of hydrophilic-lipophilic balance equal to 10 and content of the following components by wt %: non-ionic surface-active substance neonol AF_9-4 or Oxetal ID104, or Mulsifan RT - 2.0-50.0; oleinic acid - 0.1-10.0; organic bentonite - 0.1-25.0; hydrocarbon phase - remaining part at the following ratio by wt %: inverter of the 2^nd type - 10-20; drilling mud representing oil-in-water emulsion - remaining share up to 100. The invention is grounded in subclaims.

EFFECT: capability of drilling fluid to change emulsion type notwithstanding temperature under phase inversion mechanism, controllability over emulsion type depending on process needs in drilling conditions whereon drilling fluid acquires optimal properties.

4 cl, 2 tbl