Special shut off device for liquidating blowout from the drill string
Petr Bujok, Martin Klempa, Jakub Ryba, Michal Porzer, Marek Jakubčík, Lukáš Štastný, Robert Rado
Vol. 35, no. 1 (2018), pp. 309-320, [1]
Crude oil and natural gas belong to the most important raw minerals used by industry. Their world’s consumption remains on a high level with an increasing tendency, similarly the demand for exploration-prospecting works. The drilling works associated with reservoir prospecting and development are connected with the risk of reaching intervals containing highly pressurized formation fluids and with blowouts. When drilling the first well in a given area, the operator frequently does not have a full set of data about reservoir parameters of the drilled horizons. Investors want the drilling companies finish their works in the shortest possible time, therefore technologies which maximize the drilling advancement are employed. One of such techniques is drilling with minimally higher hydrostatic pressure of mud as compared to the reservoir pressure. If the drilling hits a porous interval of elevated reservoir pressure, reservoir fluid may inflow to the wellbore. If the hydrostatic pressure of fluid column in the wellbore is lower than reservoir pressure, the wellbore will be fed with reservoir water, which will consequently migrate towards the top of the well. This may result in a kick and then a blowout. The inflow to the wellbore can be handled only by well trained crew and appropriate equipment. The crew has to recognize the flow, and depending on the condition of the well take suitable measures. Sometimes the lack of proper training, errors, hardware failures and improperly protected top of the well lead to a fully developed blowout from the well. Particularly dangerous are cases when the surface blowout prevention equipment or other elements of the well BOP facilities break down. In such situations rescue teams with specialist equipment have to be involved. Exemplary applications and technological potential of specialist blowout control equipment in uncontrolled kick of reservoir fluid though the string are presented in the paper. The designed tool and its functions allow for killing or reducing the outflow.