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Statoil

Snohvit C02 Tubaen Fm. storage capacity and inj«ction strategy study

Valid from

Rev. no. 1.0

Figurę 87: Fluid pressures (RFT) and leak-off pressures as functions of depth forthe North Sea Central Graben (from    ). The dotted linę indicate the

assumed linear S₃ depth trend, which gives a constant Sv / S₃ relationship with depth.

	Depth	Depth difference	S3	S3 uncertainty	S3 uncertainty	S3,2,28 g/cc	S3,2,3 c^cc		S3 Difference
	(mTVDRKB)	(m)	(glcc)	(flfcc)	(bars)	(bar)	(bar)	(bar)	(bar)
XLOT	2400	0	1.55	0,03	7	365	365	365	0
Top Tubaen (4)	2586	186	1,60	0,03	8	407	407	408	1
Top Tubaen 3	2639	239	1,62	0,03	8	419	419	421	2
	2650	250	1,62	0,03	8	421	421	423	2
iESBESH	2683	283	1,63	0,03	8	428	429	431	3

Table 4-6: Extrapolations of S* estimates from the XLOT in the Snohvit area. The Sj estimate is extrapolated from the depth of the XLOT in the Sto Formation and down to the 4 injection formations in the Tubaen Formation.

Table 4-6 show that porę pressures of 407, 419, 421 and 429 bars should be tolerated before Tubaen 4, 3, 2 and 1 generate tensile fractures. For comparison,    estimated Sj to be 394 bars at 2580 m TVD MSL. A

net fracturing pressure should be added to the estimated Sj value (which represent the fracture closure pressure) to obtain the actual fracture pressure. However, it is commonly recommended to neglect this in order to have conservative numbers and safety limits for the estimated fracture pressures. (The net fracturing pressure is a function of ratę, viscosity, stiffness and fracture geometry) (Cemmer, pers, comm).

Classification: Intemal Status: Draft Expiry datę: 2012-12-31 Page 103 of 132