Subsea control system diagnosis
AssigneeChevron U.S.A. Inc.
InventorsBaha Tulu Tanju, Hailing An, Ashish Karamchandani
Life of this patent
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Abstract
Accurate, dependable methods for analyzing operational parameters of subsea control systems and diagnosis/prediction of failures are provided, in particular, methods for detection of leaking and/or clogging in hydraulic control system using recorded pressure signals and evaluating response communication strength (signal amplitude) of field equipment from, for example, subsea control systems. Prediction of failure(s) allows an opportunity to prepare for intervention to minimize the impact of failure before failure occurs, for example, by ordering equipment, tools and/or scheduling an intervention vessel. Similarly, diagnosing a failure drastically shortens the intervention time.
Claims19
A method for monitoring the health of a hydraulic control system comprising:
- a) capturing a layout and parameters of the hydraulic control system;
- b) capturing a valve signature during a System Integration Test;
- c) generating a simulated valve signature to match the valve signature captured during the System Integration Test by using a simulation algorithm and adjusting parameters of the hydraulic control system;
- d) recording the parameters of the hydraulic control system used to generate the simulated valve signature that matches the valve signature captured during the System Integration Test;
- e) capturing a valve signature for a subsea valve opening/closing;
- f) generating a simulated subsea valve signature to match the subsea valve signature captured for the subsea valve opening/closing by using the simulation algorithm and adjusting parameters of the hydraulic control system;
- g) recording the parameters of the hydraulic control system used to generate the simulated subsea valve signature that matches the valve signature captured for the subsea valve opening/closing;
- h) repeating steps e), f) and g);
- and
- i) tracking changes in the parameters of the hydraulic control system over time.
A method for determining performance of a hydraulic control system comprising a directional control valve, the method comprising:
- a) recording valve signatures comprising pressure readings recorded during accumulator recharge from pressure sensors;
- and
- b) comparing the valve signatures;
- wherein:
- an increased pressure differential of the valve signatures with increased pressure indicates a leak;
- and
- the valve signatures being parallel indicates sensor drift.
A method for determining whether a leak and/or clog exists in a hydraulic control system comprising:
- a) recording valve signatures from pressure sensors in the system during system integration testing;
- b) calculating an initial flow resistance, Cv0, using the recorded valve signatures during system integration testing and actuator volume, Vact;
- c) recording valve signatures from the pressure sensors during operation of the system;
- and
- d) calculating a value for
- ∫
- 0
- T
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- Cv
- 0
-
-
- p
-
-
-
- t
- during operation of the system, wherein dp is a pressure differential between the pressure sensors over time during operation of the system, and T is actuator opening time;
- wherein a calculated value for
- ∫
- 0
- T
-
- Cv
- 0
-
-
- p
-
-
-
- t
- greater than Vact indicates leaking and/or clogging in the hydraulic control system.
A method for monitoring a communication system of a subsea system comprising:
- a) measuring a maximum amplitude of analog signals transmitted from a subsea control module to a topside modem;
- and
- b) comparing the maximum amplitude of the analog signals transmitted from the subsea control module to the topside modem over time.
Dependencies are inferred from the claim text.