Abstract
Cap rock integrity is one of the key safety concerns for any fluid injection operations. The estimated minimum in situ stress in the cap rock is one of the inputs used to set the injection pressure limits. These stress magnitudes are typically derived from models that are calibrated to available direct or indirect field measurements. Traditionally, stress measurements are acquired as part of drilling operations to pressure test casing shoes. However, availability of high quality data in deep water environments is very limited because of various operational constraints and concerns over weakening and damaging of wells and the formation. To address these challenges, we shifted our data acquisition strategy focus from drilling to well abandonment operations. One of the key advantages of this acquisition strategy is the flexibility and variety of tests that can be performed. The frequency and location of tests can also be tailored to different operations throughout our assets. With this new strategy, we can acquire measurements throughout the full life-cycle of the field. This shift in focus also provides us unique opportunities to acquire high quality measurements directly in the zone of interest without risking the integrity of the well during drilling operations or the cap rocks. In this paper, we intend to highlight several examples to demonstrate how we have successfully integrated and utilized this new data acquisition strategy throughout our deep water portfolios.
1. INTRODUCTION
Produced water reinjection, waterflood, steam injection, cutting reinjection, CO2 injection and gas injection have become essential components for field developments around the world. Integrity of the cap rock is one of the biggest safety concerns for successful execution of these operations. Defining a robust injection operation guideline for waterflood or produced water reinjection that achieves maximum pressure/rate while preventing out-of-zone injection has become a critical geomechanics challenge. The reliance on full-scaled Mechanical Earth Models and other analytical or empirical fit-for-purpose models to address safety concerns in the deep-water environment has increased significantly over the last decades:
• Maximizing injector performance while ensuring cap rock integrity and containment by defining safe injection guidelines.
• Enhancing our ability in safely delivering wells by making better estimates of drilling margins for well planning and design in challenging drilling environments.
• More reliable input parameters for studying underground blowouts and worst case discharge scenarios.
• Optimizing field development strategy through realistic forecasts on production- and/or injectioninduced deformation that can cause damages to well integrity and surface facilities.
