Effectiveness of High-Performance Water-Based Spacer Systems for Curing Lost Circulation in Permeable Reservoirs During Cementing Operations

摘要

Geological components of reservoirs vary across geographic regions. A typical reservoir environment comprises various characteristics: the kind of hydrocarbons it contains, the level of consolidation and unconsolidation, formation porosity, permeability, pore and fracture pressure characteristics, depleted reservoirs and many more. It is common to observe lost circulation during the drilling and cementing phases of a well spudded in permeable or unconsolidated reservoir environments. Various lost circulation prevention techniques can be deployed to minimize losses. These techniques include incorporating the best drilling practices to equipping the mud or cement system with effective lost circulation control materials. Losses experienced during the drilling or cementing phases of oil or gas wells can result in an underbalanced reservoir environment that can ultimately have devastating consequences on drilling activities. Losses can either be minor or partial to complete losses, depending on the unaccounted volume lost into the formation at any specified period of time. This situation is usually monitored by accounting for the volumes of drilling mud/ fluid pumped in hole with respect to the volume out at the mud pits. In the cementing phase, uncontrolled losses often lead to the reduction of the annular height of cement behind the casing, resulting in poor zonal isolation. Cementing applications have been improved to control losses by integrating a lost circulation control system in either or both the cement slurry or/and spacer system. This paper showcases the efficiency of a high-performance water-based spacer system deployed on a well section where lost circulation was a major challenge. The paper presents how this spacer system effectively controlled losses and enhanced zonal isolation while achieving the desired annular height of cement and an excellent cement bond evaluation log.