Numerical Simulation of Water and Sand Blowout When Drilling through Shallow Water Flow Sediments during Deepwater Drilling

Abstract

A geological model of typical shallow water flow (SWF) sediment in deepwater basins is constructed based on its basic characteristics, and a reservoir simulation model is then established that incorporates two-phase flow as the basis for the simulation of water and sand blowout process during penetrating SWF formations. The model assumes that sands can start flowing along with water at a critical pressure difference when drilling through SWF formations. The cumulative water and sand blowout as SWF formations are penetrated are calculated and the influencing factors, such as SWF zone size, overpressure factor of SWF formations and penetration rate, are incorporated into the model to quantitatively analyze their impacts on the water and sand blowout from SWF zones. The data are useful for the assessment of the severity of SWF hazards. The results show that the cumulative water blowout and sand blowout will be as high as 100m3 and 1m3, respectively, when a typical SWF sediment is totally penetrated. SWF formation overpressure factor has a remarkable effect on SWF blowout, while SWF zone size has more moderate effects. However, the effects of SWF sediment size are expected to become increasingly significant as time proceeds. 10% increase of overpressure factor of SWF formation will result in around 90% increase of cumulative water blowout and 150% increase of cumulative sand blowout after the SWF zone is totally penetrated, while 10% increase of SWF zone size will lead to about 20% elevation of cumulative water blowout and 25% ascending of cumulative sand blowout. The water and sand blowout can be effectively reduced while increasing the penetration rate, which indicates that elevating the penetration rate can be a useful measure for the control of SWF hazards during deepwater drilling operations.

A Parametric Study of Coupled Hydromechanical Behaviors Induced by Shallow Water Flow in Shallow Sediments in Deepwater Drilling Based on Numerical Modeling

“…To further verify the numerical model, water production caused by shallow water flow in a deepwater drilling scenario is simulated and verified against the published data from Gong et al [23]. The water depth is 1500 m with shallow water flow encountered between 500 to 600 m below the mudline.…”

“…The sediments buried in shallow water flow zones can be treated as fully saturated porous media [5,20,23,24]. In a coupled hydraulic-mechanical problem, both subsurface water flow and rock deformation should be considered.…”

“…In the same region, Reece et al [22] correlated compressibility, permeability, and porosity which are key parameters governing the fluid flow in the formation. Gong et al [23] and Ren et al [24] proposed a numerical model that simulates water and sand flows induced by deepwater drilling through overpressured zones, where the heavy oil flow is used as a proxy which represents the sand flow. In their shallow water flow model, both water and sand flows strictly follow Darcy's law and petroleum reservoir simulation practices were widely implemented.…”

“…According to the literature review, numerical modeling is effective in the characterization of shallow water flows. Specifically, Darcy's law, the equation describing subsurface flow in porous media, was proved to be useful and has been successfully used in the quantification of shallow water flows in the porous media buried beneath the mud line [5,[23][24][25]. Meanwhile, it is noted that not many studies were carried out to investigate the coupled behaviors of subsurface fluid flow and rock deformation in the context of deepwaterdrilling-induced shallow water flows.…”