Riserless Drilling: The Technique to Contain Shallow Hazards in Deepwater Exploration Wells

Pratap V. Nair

Abstract: Deepwater exploration often faces tight drilling margins from the mudline, with pelagic rocks and an overburden-parallel pore-pressure profile. Because seismic imaging cannot effectively resolve shallow-water overpressured sands, a precisely planned well is essential to reach the planned total depth. In deepwater drilling, the marine drilling riser transports fluids from the seafloor to the drill floor of the mobile offshore drilling unit. Typically, the first few thousand feet of drilling are performed riserless, meaning no riser is used to manage shallow-water overpressured sands and narrow drilling margins. During risered drilling, drill cuttings and mud are brought up to the drill floor, whereas in riserless drilling, these returns are released onto the seabed. The dual-gradient mud system mitigates shallow hazards and enables safe drilling to greater depths in deeper waters while keeping costs under control. This technology enables oil and gas exploration in deep waters.

Keywords: Deepwater, Narrow margin, Pore pressure, Challenges, Shallow water flow, Riserless, U tubing

How to Cite?: Pratap V. Nair, "Riserless Drilling: The Technique to Contain Shallow Hazards in Deepwater Exploration Wells", Volume 15 Issue 9, September 2026, International Journal of Science and Research (IJSR), Pages: 1890-1897, https://www.ijsr.net/getabstract.php?paperid=SR26928103736, DOI: https://dx.doi.org/10.21275/SR26928103736

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