RIASSUNTO
Abstract
Modern well intervention operations bring with them serious risk of non-productive time (NPT) and cost escalation through the customary practice of working ""blind?? - that is, by relying solely on surface measurements such as RPM, hook weight and rotary torque to manipulate well intervention tools tens of thousands of feet downhole. Often the true results of these manipulations are not known until the bottomhole assembly (BHA) has been retrieved to surface, and then further trips become necessary to complete a satisfactory intervention operation. Until now, there has been no accurate or consistent method for observing the forces and conditions experienced in the downhole intervention environment.
A new system has been developed to present quantified parametric downhole tool force and environment information to the operator at surface in real time and thus enable on-the-spot decision making for the optimization of well intervention operations. The system integrates a sensor sub and a basic measurement while drilling (MWD) tool into the intervention BHA. Standard mud pulse technology transmits signals to surface for decoding and visualization by an independent standalone unit.
A significant number of successful operations have been conducted during system integration testing, and the first commercial jobs have just been completed. This paper will demonstrate the benefits of real-time data enabling real-time decision-making in challenging well intervention scenarios, and through case history data, elucidate new refinements in the system architecture.
Introduction
Real-time data in the drilling phase of a well is a basic operational premise. Every Operator has seen the benefit of using MWD technology for well placement and logging. But on the intervention side, use of this technology is in its infancy. Wellbore intervention operations - fishing for example - are often viewed as a physical skill or intuitive sense honed only through years on the rig floor. The use of real-time data and technology is changing those outdated perceptions.
The foundation for this new technology in wellbore interventions is a downhole tool capable of measuring and transmitting environmental parameters. Since the majority of intervention work is run on either drill pipe or coil tubing, MWD technology was a perfect fit for purpose solution.
MWD Data Transmission
MWD is the process of acquiring measurements from downhole sensors in a drilling assembly and transmitting those measurements via wireless telemetry. In an intervention application, a well intervention assembly replaces the drilling assembly. Although a well intervention workstring is often interchangeable with a drillstring, the BHAs are vastly different, but the fluid pulse technology remains the same for the well intervention arena.