9345765570

1

Statoil

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

Valid from

Rev. no. 1.0

case, according to the modelling results in the table. Since the closest fault is 750 meters away from the injector, it is concluded that it is also unlikely that the thermal cooling will influence fault stability and reactivation ( ).

Hydrau k	Cchesicr	Fricton	Fau t tyce	Faul: tvpe	Fau traact vation?
open cr cloted?	:VFa)	ancie o		probat lity	ubaaen	Tubaaer	Tibaaen	T u baaen	T.ioiaen	“ubaaer
					p'essure »370br.r	pressu-e =38''bar	pressure	oresil re =400 łvr	pressure = 410nai	pressure =4 70ba-
						aP=023j/	±P=^9 »>2tar	ar-rzbar	iP=12.'ta	iP= 132bfi
Cpen	3	20	WeaF shale	Lw	•''es	Ye>	Yes	Yes	Yes	^ves
				0.05
Próba btlitv		30	weak	Ldw	KO	Ye>	Y€$	res	YłS
O 2S			sands.cne	0.15
	13	20	$ł*a e	Sc me	KO	Nc	No	MO	NO	Ho
				0.2
		50	5ands:cne	Llkely	KO	NC	NO	Md	NO	NO
				0 5
Clo;?c	3	20	Weak ;hale	Izy:		Ye;	Yes	Yec	Yii
				0 05
PiobabilitY		30	Weak	L:y.'	KO	Nc	NO	re<		^ves
0 ;S			;ands:cne	0.15
	13	20	<Fa e	Sc mc	Ko	Nc	No	Md	No	No
				o:
		30	San ds*.cne	Likely	KO	Nc	NO	Md	NO	No
				O.S
1 F&L t rc					ocs	0 0375	5.03^5	02	0 2	C.2

ix(ivaicn prcbit 11/

Table 4-7: An overview of which models that lead to fault reactivation and their associated probability (From )

However, the geomechanical model also shows that if the faults are hydraulically open and the faults lack cohesive strength there is a chance for fault reactivation at porę pressures down to 370 bars at the fault location (Table 4-7). The total chance for reactivation of faults in this case is estimated to be around 20 % for porę pressures between 370 and 400 bars. Morę specifically, if a PI 0 probability of fault reactivation is acceptable, the Tubaen Fm can be pressured up to 390 - 400 bars, and if a P5 probability is acceptable the pressure limit is 370 bars

).

Unfortunately, little knowledge exists on how to predict cohesiveness of faults. Some examples of geological factors that control such fault behaviour is listed below:

Some factors that will enhance cohesiyeness within fault zones: o Ductile rocks/clay smear o Deep burial/cementation

Fault gouge deformation processes (cataclasis, disaggregation)

No recent movement of faults

Classification: Intemal Status: Draft Expiry datę: 2012-12-31 Page 105 of 132