Patent ID: 9605499
Date: 2017-03-28
CPC Classifications: E21B

Claim:
1. A subsea wellhead pressure indicating and automatic adjusting device for deep-water dual-gradient drilling, comprising: a subsea drilling fluid manifold system and a subsea wellhead pressure indicating and automatic adjusting system, wherein the subsea drilling fluid manifold system provides a flow channel for the drilling fluid returning through a wellbore so that the drilling fluid is configured to smoothly return to a drilling platform, and provides a basis for the subsea wellhead pressure indicating and automatic adjusting system; and wherein the subsea wellhead pressure indicating and automatic adjusting system is configured to display and to adjust the subsea wellhead pressure in real time, in order to keep the subsea wellhead pressure to be constantly equal to a hydrostatic pressure of seawater at seabed, ensuring successful implementation of the dual-gradient drilling, wherein the subsea drilling fluid manifold system comprises: a first tee joint, a first flat gate valve, a second flat gate valve, a first pressure gauge, a second tee joint, a third tee joint, a hydraulic throttle valve, a check valve, a subsea mud pump, and a second pressure gauge, wherein an inlet of the first tee joint is connected to a subsea wellhead device through a drilling fluid discharge pipeline, a first outlet of the first tee joint is connected to an inlet of the first flat gate valve through a pipeline, an outlet of the first flat gate valve is connected to an inlet of the second tee joint through a pipeline on which the first pressure gauge is arranged, and a first outlet of the second tee joint is connected to a first inlet of the third tee joint through a pipeline; a second outlet of the first tee joint is connected to an inlet of the second flat gate valve through a pipeline, and an outlet of the second flat gate valve is connected to a second inlet of the third tee joint through a pipeline; an outlet of the third tee joint is connect to a fluid inlet of the hydraulic throttle valve through a pipeline, a fluid outlet of the hydraulic throttle valve is connected to an inlet of the check valve through a pipeline, an outlet of the check valve is connected to an inlet of the subsea mud pump through a pipeline on which the second pressure gauge is arranged, and an outlet of the subsea mud pump is connected to the drilling platform through a drilling fluid return pipeline.