In the Bohai Bay basin,because of the existence of thick active soft shale in sedimentary formation,downhole problems happen frequently and hydrocarbon reservoir is damaged in a certain degree when drill this shale interval using ordinary polymer drilling fluid system with poor encapsulating ability,weak formation sealing ability,and bad shear thinning property.

Research on the hard brittle shale and drilling fluid type in WZ 12-1N oilfield;

To solve the borehole instability in brittle shale because of micro-fractures,this paper set up a new evaluation method of hard brittle shalethe simulation and sealing about micro-fracture.

It was characterized by complex geological structure, lots of fractures and folds under the influence of Himalayan tectogenesis, Specially for the hard brittle shales with a quantities of micro-fractures in this area, serious problems such as borehole instability, and pipe sticking occurred frequently during the borehole drilling.

Wellbore instability caused by brittle shale is a very complex problem during drilling.

Compressing parameter of Ningming expansive shale for construction;

New calculation method of membrane efficiency of shale;

Apparatus for testing shale membrane efficiency and its technique;

Pressure transmission testing technology and simulation equipment for hydra-mechanics coupling of shale;