Experimental Study and Stabilization Mechanisms of Silica Nanoparticles Based Brine Mud with High Temperature Resistance for Horizontal Shale Gas Wells

Table 4

Testing conditions and results of pressure transmission tests.

Number of shale; samples	Testing fluid	Permeability; (mD)	Reducing rate; of permeability (%)	Testing conditions	Test time; (h)
1#	10% NaCl	0.91	—	Upstream pressure: 2.3 MPa; Downstream pressure: 0 MPa	3
	7% NaCl + 3% KCl	2.72 × 10^−3	99.7		30
	NPBM-1 at 25°C	1.96 × 10^−6	99.99		40
	NPBM-1 at 25°C	1.5 × 10^−5	99.99	Upstream pressure: 10 MPa; Downstream pressure: 0.02 MPa	30
2#	10% NaCl	1.89	—	Upstream pressure: 2.3 MPa; Downstream pressure: 0 MPa	3
	7% NaCl + 3% KCl	2.17 × 10^−3	99.89		30
	NPBM-1 after being rolled at 180°C	4.69 × 10^−6	99.99		60
	NPBM-1 after being rolled at 180°C	1.29 × 10^−5	99.99	Upstream pressure: 10 MPa; Downstream pressure: 0.02 MPa	20