NON-DARCY FLOW PARAMETERS FOR EVALUATING CAPROCK INTEGRITY ASSOCIATED WITH GEOLOGICAL CO2 SEQUESTRATION AND STORAGE
Systems and methods for determining caprock integrity for geological sequestration of CO 2 , such as in above saline aquifers. The testing system for performing the method includes a core container in fluid communication with an upstream reservoir and an upstream pump, further in fluid communication with a downstream liquid reservoir and a downstream liquid pump, and further in fluid communication with a downstream gas reservoir and a downstream gas pump. The method includes determining transient hydraulic conductivity and hydraulic gradient of a caprock core sample using the testing system based on non-Darcy flow.
1 . A method comprising:
determining a hydraulic gradient and a hydraulic conductivity of a caprock core sample based on non-Darcy flow using a testing system comprising:
a core container comprising an upstream inlet, a downstream outlet, and a confining pressure pump in fluid communication with the core container;
an upstream reservoir in fluid communication with the upstream inlet and comprising a first upstream valve for selectively controlling fluid flow between the upstream reservoir and the caprock core sample located within the core container;
an upstream pump in fluid communication with the upstream reservoir and comprising a second upstream valve for selectively controlling fluid flow between the upstream pump and the upstream reservoir;
a downstream liquid reservoir in fluid communication with the downstream outlet of the core container and comprising a first downstream valve for selectively controlling fluid flow between the downstream liquid reservoir and the caprock core sample located within the core container;
a downstream liquid pump in fluid communication with the downstream liquid reservoir and comprising a second downstream valve for selectively controlling fluid flow between the downstream liquid pump and the downstream liquid reservoir;
a downstream gas reservoir in fluid communication with the downstream liquid reservoir and comprising a third downstream valve for selectively controlling gaseous flow between the downstream gas reservoir and the downstream liquid reservoir; and
a downstream gas pump in fluid communication with the downstream gas reservoir and comprising a fourth downstream valve for selectively for controlling gaseous flow between the downstream gas pump and the downstream gas reservoir;
wherein the determining comprises:
closing the first upstream valve, the second upstream valve, the first downstream valve, the second downstream valve, the third downstream valve, and the fourth downstream valve;
arranging the caprock core sample in the core container, wherein the core container is pressurized using the confining pump to a predetermined confining pressure;
equilibrating the testing system by:
opening the first upstream valve, the second upstream valve, the first downstream valve, and the second downstream valve to saturate the caprock core sample with water;
opening the fourth downstream valve, thereby providing gaseous flow to the downstream gas reservoir until a predetermined equilibrium gas pressure in the downstream gas reservoir is reached;
closing the second downstream valve and the fourth downstream valve when the predetermined equilibrium gas pressure is reached;
opening the third downstream valve; and
thereafter, closing the first upstream valve;
performing a flow test by:
opening the second upstream valve, thereby pressurizing the upstream reservoir using the upstream pump to a predetermined pressure; then keeping constant the pressure in the upstream reservoir;
opening the first upstream valve, thereby flowing water between the upstream liquid reservoir and the downstream liquid reservoir through the caprock core sample;
measuring flow rate data between the upstream inlet and the downstream outlet as a function of time; and
measuring pressure differential data between the upstream outlet and the downstream outlet as a function of time;
collecting the flow rate data and the pressure differential data;
calculating hydraulic conductivity (K) of the caprock core sample as a function of time where
K
=
q
0
L
Δ
p
+
A
L
2
6
d
(
ln
Δ
p
)
dt
,
and q 0 is the flow rate data at the upstream inlet at time zero (0), L is a length of the caprock core sample, A is a storage factor, and Δp is the pressure differential data; and
calculating the hydraulic gradient (i) of the caprock core sample as a function of time where
i
=
1
L
(
Δ
p
ρ
g
+
Δ
z
)
,
and ρ is porosity of the caprock core sample, g is gravitational acceleration, and Δz is an elevation difference between the upstream inlet and the downstream outlet.
2 . The method of claim 1 , further comprising repeating the equilibrating and performing steps if the measured pressure differential between the upstream inlet and the downstream outlet has not changed with time.
3 . The method of claim 1 , wherein installing the core container comprises enclosing at least one sleeve about the caprock core sample.
4 . The method of claim 3 , wherein the core container is pressurized using the confining pump by pumping a confining fluid into core container outside of the at least one sleeve.
5 . The method of claim 1 , wherein the upstream pump in the testing system pumps water into the upstream reservoir and the downstream pump in the testing apparatus pumps water into the downstream liquid reservoir.
6 . The method of claim 1 , wherein the caprock core sample has a diameter in the range of 1 inch to 4 inches, and an axial length in the range of 1 inch to 2 inches.
7 . The method of claim 1 , wherein the caprock core sample has a diameter of 1 inch and an axial length of 1 inch.
8 . The method of claim 1 , wherein the predetermined confining pressure is in the range of 500 psi to 5,000 psi.
9 . The method of claim 1 , wherein the predetermined confining pressure is in the range of 500 psi to 2,500 psi.
10 . The method of claim 1 , wherein the caprock core sample is collected from above a saline aquifer, the saline aquifer for sequestration of CO 2 .
11 . The method of claim 1 , wherein the caprock core sample is collected from a depleted oil and gas well, the oil and gas well for sequestration of CO 2 .
12 . The method of claim 1 , further comprising estimating caprock integrity of the collected caprock core sample based on the calculated hydraulic conductivity and the calculated hydraulic gradient.
13 . The method of claim 12 , further comprising performing a CO 2 sequestration operation based on calculating the caprock integrity.
14 . The method of claim 1 , further comprising a plurality of downstream liquid reservoirs fluidly connected by a plurality of valves.
15 . The method of claim 1 , further comprising a plurality of downstream gas reservoirs fluidly connected by a plurality of valves.
16 . A system, comprising:
a core container comprising:
an upstream inlet in fluid communication with the core container;
a downstream outlet in fluid communication with the core container; and
a confining pressure pump in fluid communication with a of the core container;
an upstream reservoir in fluid communication with the upstream inlet of the core container and comprising a first upstream valve for selectively controlling fluid flow between the upstream reservoir and the caprock core sample located within the core container;
an upstream pump in fluid communication with the upstream reservoir and comprising a second upstream valve for selectively controlling fluid flow between the upstream pump and the upstream reservoir;
a downstream liquid reservoir in fluid communication with the downstream outlet of the core container and comprising a first downstream valve for selectively controlling fluid flow between the downstream liquid reservoir and the caprock core sample located within the core container;
a downstream liquid pump in fluid communication with the downstream liquid reservoir and comprising a second downstream valve for selectively controlling fluid flow between the downstream liquid pump and the downstream liquid reservoir;
a downstream gas reservoir in fluid communication with the downstream liquid reservoir and comprising a third downstream valve for selectively controlling gaseous flow between the downstream gas reservoir and the downstream liquid reservoir; and
a fourth downstream valve for selectively for controlling gaseous flow between the downstream gas pump and the downstream gas reservoir.
17 . The system of claim 16 , further comprising a pressure sensor provided at each of the upstream pump, the downstream liquid pump, and the confining pump.
18 . The system of claim 16 , further comprising a pressure sensor provided at each of the upstream reservoir, the downstream liquid reservoir, and the downstream gas reservoir.
19 . The system of claim 16 , further comprising a plurality of downstream liquid reservoirs fluidly connected by a plurality of valves.
20 . The system of claim 16 , further comprising a plurality of downstream gas reservoirs fluidly connected by a plurality of valves.