In recent years, as the cost of drilling, evaluating, and completing wells continues to rise in offshore, operators are seeking new technologies that offer measurements comparable to proven wireline logging technologies. Logging while drilling (LWD) technology has progressed swiftly in recent time to address the need for saving rig time by enabling real-time informed decisions for drilling efficiency and risk management. LWD sonic is traditionally used to log formation slowness in the open hole but increasingly being used in cased hole to optimize logging time and evaluate top of cement.
Before starting a hole section, well integrity is a critical input to decide if it is safe to drill ahead or additional measures are required to assure operation safety. In this case study we demonstrate that both, measuring formation slowness in open and cased hole along with evaluating the success of a cementing operation can be obtained with the latest generation of LWD sonic tools while drilling, thus saving rig time, simplifying operations, and assuring operation safety and integrity.
In this case study we demonstrate that formation slowness can also be recorded in cased hole with LWD tools when the cement bonding is sufficient to allow good coupling. This advanced technique of logging formation slowness through casing with LWD can complement conventional logging, or even save an additional logging run in some cases, and therefore result in significant savings to the operator. Where azimuthal cement evaluation is not a strict requirement, knowing the top-of-cement (TOC) from LWD can help to confirm well integrity without adding rig-time. This in turn will help to take on-time decision to plan additional logging requirements for advanced analysis