UDAR: Past, Present, and Future: An Operator’s Experience and Perspective on the Challenges and Opportunities in Applications With Ultradeep Resistivity Tools

Abstract

Proactive geosteering, landing, geostopping, geomapping, and look-ahead (LAH) applications of ultradeep azimuthal resistivity (UDAR) tools are becoming more common in operator new well delivery practices. In very specific and niche wells, almost exclusively high angle and horizontal (HAHZ), the value of information provided by these tools can significantly exceed the high cost of the service. In the past, UDAR technology was primarily used only for geosteering high-value, generally offshore horizontal wells, where the objective is typically to increase net pay. As time progresses, the application of UDAR has grown past HAHZ-limited applications to now include look around for geomapping and look ahead for geostopping. From an operator’s perspective, the justification for the high cost of UDAR is always challenged by not only the uncertainty of what the tool will deliver but what will be the reasonable actions based on the provided deliverables at the time of drilling. UDAR service companies seem to be in a depth of detection (DOD) “arms race,” but what operators really want is a greater understanding of uncertainty with the goal of better well delivery through confident decision making. One way to hedge this risk is to have a clear key performance indicator (KPI)-based pricing strategy, where vendor predrill study claims are tested during and after drilling, and compensation is based on their validation. Another limitation contributing to the underutilization of the UDAR service, and associated operator increased risk exposure, is the present-day inability for operators to verify predrill studies, real-time inversions, and post-drill interpretations via in-house modeling. Modeling is particularly important for the UDAR service, where the scientific and mathematical complexity of inversion extends far beyond human intuition. We believe that with the right application and pricing strategies, UDAR could grow past the high-value/high-cost portfolio of the past and be used on a more typical borehole assembly (BHA) in the future. In this paper, we will discuss our UDAR journey thus far, including reflections on past applications and present challenges, and we will propose some improvements, including standardization, that we hope the industry accepts to grow the quality and the number of future applications.