Drill-tool check Valve
|Drill-tool check Valve is a main Blowout prevent toolin drill tool and should be classified into four kinds ac-cording to its structure, i.e. arrow back pressure valve(FJ), Ball check valve(FQ), Butterfly check valve(FD) and Drop-in check valve。
Arrow-Shaped Check Valve
|Arrow check valve
The arrow check valve is one of inner blowout pre-vent tools that are commonly used in gas drill and re-pairing well, and is a kind of in-string blowout preventback pressure valve accompanying the drill enteringwell,once well-leakage and well blowout happen, it canautomatically and quickly shut the bore of valve by theupper inverse circulation pressure and plug the water-way of string so as to avoid the blowout and ensurethe safety of drilling equipment and person-life.
In addition, it can meet the normal kill requirement; alsoprovide inner sealing operation condition for someparticular operations, such as retrieving tool and drillingas blowout without kill or repairing well.
|Drop-in check valve
Drop-in check valve, as an important toll to preventwell kick and a BOP inside drilling string, which isdropped into well and prevent well kick and blowout justas necessary, is used to control the inner pressure ofdrilling rod as running/retrieving drill is forced under wellkick or a certain pressure. For it is not connected withdrilling rod, it is convenient to execute various drillingoperation.
As overflow happens under ground, the check valveis dropped or pumped into the water hole of the Kelly,and moves to be held against the shoulder of the stopring connected with the bottom of the on-stationconnector, the cone of the valve moves up, some hacklelock-teeth of on-station connector and the teeth-blockin the top of the check valve are locked each other, thecone moving up forces packer to dilate so as to seal thebore-wall, in the bottom hole sets steel ball and spring,the spring can load the steel ball into the sealing seat ofthe valve body, so that a strict seal mechanism is formed,here the on-station connector and check valve assem-bly composes a set of internal-BOP assembly.
|Upper/lower Kelly Cock
| Kelly cock valve is a constant-open type blowoutprotection assembly in drilling tool, as well kick happens,it can be closed and prevent fluid under ground fromgushing up through the water hole in drilling column. Inwell control operation, if hose and high-pressure mani-fold is damaged, it can be replaced in safety under thevalve being closes.
Upper cock adopts left hand thread but the loweradopts right hand thread, and they are identical instructure of ball valve.
The rated working pressure of Kelly cock valveshould be equal to the rated pressure of BOP, the ID ofcock should be larger than (or equal to) the ID of Kelly rod, Max working pressure and test pressure should betested according the requirement listed in the belowtable,Holding pressure for 3 minutes without leakage isconsidered as a qualified sealing test, appliance for cockis up to 82OC and the cock wrench should stay the avail-able/usable position.
Upper cock valve consists of valve body, upper/lower seat, ball body, rotary-block, retainer, spring andnon-metal seals etc.
Valve body is ASTM4140 forging, and the machin-ery properties after heat treatment can meet the require-ment of API Spec 7.
Valve seat and ball body are made of heat-resis-tant stainless steel with abrasion and corrosionresistance.
The valve is single direction seal, as the valve isclosed, under the co-reaction of fluid pressure underwell and pre-load spring pressure, the ball body ap-proaches to the back-seat quickly so as to create a seal.As for the sealing face of back-seat adds a PTFE non-metal ring and reduce the compact of ball body to valveseat,So that it should have more reliable performance.
The surface of the valve body stamped with visiblesign of ” open” or ” close’ indicates the open/close stationof cock valve obviously