The Maximum-Allowable Well Depth While Drilling of Extended-Reach Wells Targeting to Offshore Depleted Reservoirs

Abstract

In depleted offshore reservoirs, pore pressure declines and consequently horizontal in-situ stresses decrease as well. This causes a very limited well depth for extended-reach drilling targeting to offshore depleted reservoirs. In this paper, based on analyzing the safe mud weight window of the depleted offshore reservoirs, a model of predicting the Maximum Allowable Measured Depth (MAMD) for extended-reach drilling targeting to offshore depleted reservoirs is developed. Meanwhile, the numerical method of the model is proposed, and the key affecting factors of the MAMD are also investigated. The results show the pore pressure depletion has obvious effects on the MAMD. With the depletion of pore pressure, the safe mud weight window appears narrower and even disappears, consequently the predicted MAMD becomes shorter. For a normal regime depositional environment in the depleted reservoirs, it may be impossible to drill with conventional drilling method in the nearby directions of the maximum horizontal in-situ stress, while it may be much safer and attain a long MAMD when drilling in the directions near the minimum horizontal in-situ stress. Moreover, the MAMD will decrease with the increase of Poisson's ratio and Biot's parameter, and its response to Poisson's ratio is more obvious. For a specific target depleted reservoir, the extended-reach drilling with a high borehole inclination may have a longer MAMD than that with a low borehole inclination. This paper presents a method for promoting the design of extended-reach drilling targeting to offshore depleted reservoirs.

Reviewing the advancements in offshore drilling technologies in the USA and their global impact

“…Partnering in offshore drilling projects is an area of concern, as it requires effective collaboration and management to ensure project success (Børve et al, 2017). Additionally, as drilling operations target offshore depleted reservoirs, there is a need to address the maximum allowable well depth while drilling to optimize resource extraction (Chen et al, 2018). Furthermore, the impact of offshore drilling on employment and the workforce is a subject of study, highlighting the need to address potential shifts in job duties and requirements in the industry (Wanasinghe et al, 2023).…”

“…The significance of these advancements is underscored by their role in enhancing the overall productivity and sustainability of offshore drilling. For instance, the development of innovative drilling techniques and tools has enabled the industry to address challenges such as drilling in depleted offshore reservoirs and managing annulus bottom hole pressure during drilling operations (Vega et al, 2016;Chen et al, 2018). Moreover, the utilization of smart monitoring systems has facilitated real-time decision-making, contributing to the regulation of drilling processes and ensuring operational safety (Vega et al, 2016).…”

Study on the Mechanical Extended-Reach Limit Prediction Model of Horizontal Drilling with Dual-Channel Drillpipes

“…Zhang et al [28] considered the effect of cuttings with a different method of calculating the cutting bed height. Chen et al [29] considered the pore pressure decrease in a depleted offshore formation. To predict the hydraulic extended-reach limit, the frictional pressure loss is usually calculated to evaluate the required pump pressure or pump power [28,30,31].…”