The time of easy-to-reach deposits and shallow wells has almost past. The reality requires the development of hard-to-reach deposits with the use of deep wells with complex, anomalous geological conditions which may hinder cementing, the final phase of well construction. The reliability of the cementing determines the “survivability” of the well, along with the quality and the volume of the oil or the natural gas.
Patent: RU 2576253
Owner of the Patent: open corporation “Tyazhpressmash”
Authors: Alexey Volodyn, Vladislav Sorokin, Nikolay Petrov, Sergey Lobodiuk, Andrei Klimov, Alexandr Deev, Alexey Vasin, Oleg Andrianov, Pavel Piatkin.
During the final phase of the construction of a deep well equipped with casing pipes for casing the borehole walls, the cementing of the space behind this casing is carried out. The drill fluid of the well is replaced with the cement mortar, which hardens and turns into a cement rock. It bonds the casing with the subsurface rock, providing a sealed structure, which is necessary for the safety of extraction, the purity, the properties stability and the required volume of, produced “black gold” or “blue fuel”. The “survivability” of the well and its working time literally depend on the durability of the cementing.
Traditional technologies and techniques do not allow the efficient cementing of the well in complex geological conditions with anomalous zones. The mixture is either absorbed by the soft rock formations or mixes with oil, oil-field water and natural gas, which reduces the quality of the cement rock.
Authors of a new technology are proposing to split the process of the casing cementing into multiple phases. To this end, the casing has nodes of mountings for the cementing specific to the geological problems: the localisation of the anomalous zones along the well depth and the properties of these zones. The mounted casing is then lowered down into the well with intermediate irrigating in order to check the well response with its problem zones for the preliminary hydrodynamic loads and to refine the hydrodynamic modes of the according subsequent cementing at different levels.
Mounting comprises of special cementing couplings distributed over the casing strictly according to the rules, and a set of drive plugs and plug-bombs. It prevents the cement from being absorbed into the problem zones and from mixing with the crude oil, oil-field water or natural gas. Independent cementing of the space behind the casing is carried out on each phase of cementing according to the given individual hydrodynamic mode step-by-step, phase-by-phase. The cement rock is moved deeper and deeper until the entire depth of the well is provided with the durable and sealed construction with the uniform cement rock.
The details of the suggested method of multistep cementing along with features of a device for its implementation are presented in the patent for the invention (RUS).