A Decision Analytic Framework for Autonomous Geosteering

Abstract

One of the objectives of Integrated Operations (IO) 1 is to automate the decision-making process in drilling operations. Such automation is essential to improve both decision quality and speed in the complex and data-rich environment of drilling operations. Over the past decade, the E&P industry has significantly improved its ability to acquire and share large data volumes at unprecedented speeds. The motivation for these investments is to increase value through increased future productions while simultaneously reducing drilling costs. However, utilizing the large data volumes is not always straightforward. Sensor measurements are uncertain because of their reading errors and possible malfunctions, and many sources of data need to be fused to provide decision-relevant information. Furthermore, many drilling operational decisions must be made with very limited time, and this makes evaluating potential alternatives based on the decision criteria by the geosteering team difficult or even impossible. Given these challenges, there is a need to develop efficient processes and tools to automatically support drilling operational decisions. In this paper, we propose a modular intelligent decision advisor (IDA) framework for supporting geosteering decisions. The first module validates and combines the sensor data to determine the probability of the sensor faults and failures as well as undesired geosteering events. These events may include a dramatic increase in drag friction factors, approaching bed boundaries, tools damage, etc. Failure to detect these events could lead to losing the steering ability and sometimes catastrophic problems. The second module proactively analyzes geosteering hazards and recommends the best alternatives. To perform the sensor validation/fusion and hazard/decision analysis, we suggest the use of influence diagrams, also known as Bayesian decision networks (BDNs). Developing an IDA can lead to the reduction of human operators from rig-sites, drawing its value from improving the human safety and geosteering efficiency. Implementing IO with its associated technologies such as large volume data transmission and computational capabilities provides the means for this autonomous decision advisor. Our results show that the BDN is a useful and relevant element in the autonomous geosteering decision-making process. IntroductionHorizontal drilling is well established as a cost effective solution for exploiting oil and gas in challenging environments such as deep water and thin formations. To place the wellbore in an optimal trajectory, the directional driller adjusts the drill-bit position (inclination and azimuth) to reach one or more geological targets. These adjustments are based on the analysis and interpretation of real-time sensor readings and subsurface model outputs, combined with subject-experts' knowledge in the team. The success of geosteering operations, therefore, relies on timely access to relevant decision-supporting information. To optimize drilling operations, operators have gradually inc...

A Decision Analytic Approach to Geosteering Operations

“…If that is the case, outstanding results should be expected, considering the time and effort spent on gathering and analyzing real-time data. However, on the basis of volumetric success statistics from 750 worldwide samples, only one in five wells drilled has met its volumetric target (Saputelli et al 2003). This low success rate indicates operators' inability to manage geological and operational uncertainties.…”

“…Because of the amount of capital invested in drilling operations and its failure to deliver on volumetric expectations (Saputelli et al 2003), how to optimize geosteering decisions warrants investigation. Giese and Bratvold (2011) illustrated and discussed the implementation of a systematic method for drilling-related operational decisions.…”

“…Well construction and maintenance are responsible for the majority of the field-development capital and operating expenditures (Saputelli et al 2003). To maximize economic benefits resulting from these expenditures, oil and gas companies are continuously increasing their efforts to place the wellbore in an optimal location with a goal to maximize future production.…”