Latest Technological Developments in Offshore Deep Mixing for Piled Oil and Gas Platforms

Abstract

This paper presents some recent technological developments in deep mixing for the offshore sector. Deep mixing methods comprise in-situ soil treatment technologies where binding materials are added and blended with the original soils in order to improve their mechanical properties. The MIxed Drilled Offshore Steel (MIDOS) pile is introduced in this paper, which takes advantage of such deep mixing technologies. The comparison between the API approach and CPT-based methods for the prediction of the pile capacity are provided to validate the capability of the MIDOS pile as a foundational element for oil&gas structures in different geological conditions. The theoretical calculations are intended for initial estimation of pile sizing only and are not intended as a detailed design method.

Review of torque models for offshore helical piles

“…where d is the shaft external diameter, and p is the helix pitch. The equation [3] was evaluated in [13] by centrifuge model tests in dry sand, using measurements of installation torque and uplift capacity of helical piles with different geometries, and a good agreement between measured and predicted results was observed. For the estimation of installation torque, [10] substituted the values of Qs and Qh (shaft resistance and helix uplift bearing capacity) in equation [3] from the model of [27] by the following expressions:…”

“…He used the original equation presented in [13], eq. [3], to correlate installation torque and uplift capacity of single-helix piles in sand:…”

“…[29] adapted the model presented in [13] for a single helix pile. [13] only related the final installation torque to the measured uplift capacity (as shown in equation [3]) and no equation was proposed by them to estimate the pile uplift capacity. [29] improved the model of [13] by including Qs and Qh (shaft and helix uplift bearing resistance) estimated by the following equations:…”

“…For offshore structures, both for oil & gas and renewable energies, driven and sometimes drilled piles are the most used foundation type [1][2][3].…”

Laboratory investigations to assess the feasibility of employing a novel mixed-in-place offshore pile in calcareous deposits

“…When reaching the final depth, the rotary drives with the shaft and the mixing tool are extracted, while the casing and the starter piece remain in place. A field trial of the MIDOS pile system was completed using a drill rig BAUER BG 42. capacity of more than 9000 kN (Igoe et al 2014;Spagnoli et al 2014).…”