Over the life of a reservoir, it is often necessary to perform monitoring operations on producing wells to verify reservoir dynamics, for example fluid contacts or fluid movement behind pipe. As the wells are produced, a change in depth of the fluid contacts provides information about the capacity of the well to continue producing hydrocarbons over time. Fluid movement behind pipe can be indicative of serious well integrity issues that often lead to costly unplanned interventions.
Pulsed neutron tools are ideal for performing these monitoring operations because they measure sensitive volumes behind the pipe; they operate in a wide range of formation and borehole salinities and are capable of locating bypassed pay zones where previous open hole data was either unreliable or non-existent.Until now, these tools have required the use of a Wireline unit to provide power, conveyance and a means to collect the data on surface. The footprint of a Wireline unit can be quite large, many times necessitating the use of third-party vessels to transport or house the Wireline unit during the logging operation. Mobilization of these assets can be costly and time consuming, complicating the decision making process and deferring production.
New and unique power management technology allows the Pulsed Neutron Decay – Spectrum tool (MPND-S) to operate safely and efficiently in memory mode on battery power, eliminating the need for a Wireline unit or Wireline. It can be conveyed on slickline, coiled tubing, or even Wireline, reducing the costs associated with mobilizing additional heavy assets. It can also be quickly deployed to remote locations, simplifying logistics, minimizing operating time and increasing safety.
In this paper, the authors will review the design and construction of the MPND-S. They will describe various operations that have been performed and how the system has demonstrated improvements in efficiency and safety when compared to standard industry technology.