Deepwater Well Survey Equipment

Abstract

With the growth in underwater construction activities, there is an increasing need for accurate seabed engineering data. Modern technology makes it possible to take samples of bottom soils with a partially disturbed structure, especially for weak silty soils and silts. Testing such samples in laboratory conditions leads to inevitable errors. Despite the constant improvement of technical means of sampling, they cannot fully replace studies of the properties of bottom soils in natural occurrence. Therefore, it became necessary to create devices for the natural study of underwater soils. The following soil investigation methods are used in deep-sea wells: stamp tests, rotational shear, penetration logging, soil cutting, pressuremetry.
 Drilling of underwater wells at the bottom is carried out from floating drilling rigs, consisting of a floating base and a drilling rig. Pontoons (catamarans, trimarans) and drilling ships (self-propelled and non-self-propelled) are used as a base. On the shelf, pontoons with retractable supports or a flooded base are more often used. The drilling rig with working equipment is usually placed in the center of the pontoon. The choice of drilling equipment is determined by the purpose of the work, the depth and diameter of underwater wells, the depth of the sea, the displacement of the drilling rig, the physical and mechanical properties of bottom, soil, etc.
 Deep-sea drilling is carried out from special vessels on which the drilling unit is mounted. Vessels with an opening bottom or a special shaft for the passage of casing and drill pipes, as well as those with retractable cantilever platforms, are used. Drilling ships and pontoons are kept in a fixed position with the help of four or six anchors attached to the bow and stern of the craft. Drilling rigs provide rotary, percussion-rotary, shock-rope, vibration, rotary suction and airlift drilling. Drilling at maximum depths in the ocean is carried out using deep-sea bottom platforms and autonomous controlled vehicles.