Maximizing Recovery in Deep-Water Gulf of Mexico Assets. Surveillance in Complex Subsalt Reservoirs

Abstract

Abstract Deep water surveillance in the Gulf of Mexico (GoM) is a very challenging and capital extensive commitment for operators. Maximizing production by understanding reservoir storage capacity and deliverability is a complex task as multiple realizations could be drawn using permanent gauges and production rates, especially when the well is not performing as expected. Gathering petrophysical surveillance that supports well work and, or well remediation in wet tree production systems is complex and challenged by well access, environment conditions (high flow rates, high pressure) and availability of sensors that provide representative measurements in such conditions. To maximize the outcome, efficient combinations of sensors are designed to provide reliable reservoir surveillance and well integrity data. The data is holistically combined to provide a quick turnaround for results that feed into decisions trees, that reduce rig time and minimize the production deferrals. In this paper we present the results of a novel sand detection instrument suitable for deep-water environments. We also present holdup instruments combined from different vendors in the same wells to address the high flow rate quantification limitations due to friction and flow regime changes. We will share several examples of time-lapse cased hole fluid saturations in complex well completions. We will share a workflow that proved successful over the recent downturn in the industry. This workflow addresses the uncertainty in nuclear attributes by using flow diagnostic sensor integration as constraints. Currently, we are the only operator in GoM running active surveillance in deep water wet trees >25k ft. This paper shares the novel techniques and instruments used to evaluate different types of surveillance and how they contributed to maximize recovery by measuring key parameters critical for reservoir modelling, such as fractional flow, time-lapse residual saturations, or flow rate splits per reservoir. Challenging the industry status quo enables us to change the game in flow diagnostics determination in our high value wells. By identifying new sensor combinations that complement the existing technology offer with novel workflows and the inventive approach to progress such solutions, we are happy to share our success and lessons learned.