US 12,480,371 B1 · Device and method for rapidly regulating downhole pressure after kick in deepwater shallow open-circuit drilling

Abstract

Disclosed are a device and method for rapidly regulating downhole pressure after a kick in deepwater shallow open-circuit drilling. The device includes a real-time monitoring device and a real-time regulation device. Aiming at deepwater shallow open-circuit drilling characteristics, the present disclosure proposes that a drilling fluid return condition at a seabed is monitored through a subsea remote operated vehicle (ROV); based on this data, whether gas influx occurs in a downhole or not and changes of the gas influx rate and the formation pressure after the gas influx are analyzed in real time, and then real-time guidance is provided for the design of key parameters such as well killing fluid displacement and density, and the well killing fluid displacement and density are regulated in real time, to achieve rapid regulation of the downhole pressure after gas influx of deepwater shallow open-circuit drilling.

A method for rapidly regulating downhole pressure after a kick in deepwater shallow open-circuit drilling, wherein the method is implemented by a device for rapidly regulating downhole pressure after a kick in deepwater shallow open-circuit drilling, and the device comprises a real-time monitoring device and a real-time regulation device, wherein the real-time monitoring device comprises a subsea remote operated vehicle (ROV), a data transmission cable, and a computer processing center;

the subsea ROV is arranged at a seabed wellhead through a pulling rope, and is configured for shooting a drilling fluid return image at the seabed wellhead in real time;
the pulling rope connects the subsea ROV and a platform, the subsea ROV is connected with the computer processing center through the data transmission cable, and the data transmission cable is tied to the pulling rope;
and the computer processing center receives the drilling fluid return image shot by the subsea ROV in real time, and analyzes a regime and height of a returning drilling fluid in real time;
the real-time regulation device comprises a signal receiving and executing mechanism, a drilling fluid injection pump, a mud pit, and a drilling fluid injection pipeline;
one end of the signal receiving and executing mechanism is connected with the computer processing center, and the other end of the signal receiving and executing mechanism is connected with the drilling fluid injection pump;
and the drilling fluid injection pump is connected with the mud pit, and is connected with the seabed wellhead through the drilling fluid injection pipeline;
and
the drilling fluid injection pipeline is provided with a valve, a pressure sensor, and a temperature sensor A, the mud pit is connected with a temperature sensor B, and the pressure sensor, the temperature sensor A, and the temperature sensor B are all connected with the computer processing center;
the method for rapidly regulating downhole pressure after a kick in deepwater shallow open-circuit drilling, comprising the following steps:
(1) real-time monitoring of a drilling fluid return condition at the seabed wellhead through the subsea ROV
by monitoring the drilling fluid return condition at the seabed wellhead in real time through the subsea ROV, transmitting the shot drilling fluid return image to the computer processing center on the platform in real time, and performing real-time analysis, by the computer processing center on the image through an image processing technique to obtain drilling fluid return flow regime parameters;
(2) real-time calculation of a downhole gas influx rate and a formation pressure
by calculating the downhole gas influx rate and the formation pressure according to the drilling fluid return condition shot by the subsea ROV and the obtained drilling fluid return flow regime parameters;
and
(3) quick response to regulate downhole pressure
by designing key parameters, as the parameters comprise well killing fluid density and displacement required by handling the kick and regulating the downhole pressure according to the calculated downhole gas influx rate and formation pressure, and controlling start, stop, and injection power of the drilling fluid injection pump;
and meanwhile, quickly preparing a well killing fluid required on the platform, and timely injecting the well killing fluid to a downhole position to regulate the downhole pressure so as to control gas influx, and monitoring and analyzing a gas influx control condition in real time through the subsea ROV;
in step (1), the drilling fluid return flow regime parameters comprise a distance x from a drilling fluid return position to a drilling fluid return center and a drilling fluid return height H(x);
the computer processing center obtains the distance x from the drilling fluid return position to the drilling fluid return center through the image processing technique, and a flow regime of the returning drilling fluid in deepwater open-circuit drilling conforms to a normal distribution function:
H
⁡
(
x
)
=
1
2
⁢
π
⁢
a
⁢
exp
⁡
(
-
(
x
-
b
)
2
a
2
)
(
1
)
wherein H(x) is the drilling fluid return height, in m;
x is the distance from the drilling fluid return position to the drilling fluid return center, in m;
a is a square root of x variance, in m;
and b is an expected distance value, in m;
a maximum drilling fluid return height without the gas influx is calculated according to the following formula:
H
m
⁢
ax
=
1
.
0
⁢
6
⁢
5
⁢
d
⁡
(
v
m
d
⁢
g
⁡
(
ρ
-
ρ
a
)
/
ρ
)
1.287
(
2
)
wherein Hmax is the maximum drilling fluid return height, in m;
d is a return outlet equivalent diameter, in m;
g is gravitational acceleration, in m/s2;
ρ is a drilling fluid density, in/cm3;
ρa is seawater density, in g/cm3;
and vm is a flow velocity of the returning drilling fluid, in m/s;
and
a maximum drilling fluid return height with the gas influx is calculated according to the following formula:
H
ma
⁢
x
=
4
.
7
⁢
4
⁢
4
⁢
d
⁡
(
v
m
d
⁢
g
⁡
(
ρ
-
ρ
a
)
/
ρ
)
0.4715
.
(
3
)

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Device and method for rapidly regulating downhole pressure after kick in deepwater shallow open-circuit drilling

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Device and method for rapidly regulating downhole pressure after kick in deepwater shallow open-circuit drilling

Life of this patent

Abstract

Claims6