Abstract

This paper presents a workflow method that has been designed to improve well placement accuracy, enhance decision-making and decrease cycle time through rapid geologic model updates. This workflow was applied successfully to a horizontal well located in a giant oil and gas field offshore Abu Dhabi, United Arab Emirates. This workflow involves geomodeling, well design, synthetic log creation, real-time geosteering, and updating the geological model while drilling.

Drilling a horizontal well in this environment presents several challenges due to complex geology, heterogenous carbonate reservoir and layer thickness. In addition, there are many uncertainties reflected in the 3D geological model and while drilling.

The primary aim of this workflow is to minimize drilling time with maximum efficiency and optimum well placement. This is achieved through designing the well in the same model centric environment where the geological model was built allowing access to all available data and information for accurate well placement. Secondly, to reduce non-visible loss time and take faster decisions using real-time information. Thirdly, to evaluate associated geological uncertainties in 3D models. Finally, the use of the latest technology available in the market to meet field development requirements.

Great value was added when a 3D model was generated and updated in real time, in addition to the forward-modeling technique that assists the operation geologist to geosteer within the thin layer of the heterogeneous carbonate reservoir in order to achieve the optimum well placement in the minimum amount of time.

Introduction

The oil and gas industry is continually looking for ways to reduce the time from exploration to production, thus reducing costs and cycle time. One way in which ADMA-OPCO achieved this was through the design and implementation of a real-time 3D modeling and geosteering workflow in which processes are streamlined and decision making is accelerated.

This paper outlines the real-time 3D modeling and geosteering workflow that was designed to improve well placement accuracy, enhance decision making, and decrease cycle time through rapid geologic model updates.

Petrel technology was used prior to drilling the well to prepare a 3D geological model of the reservoir incorporating all available geophysical and geological information to get a complete overview of the distribution of the petrophysical properties through the field. While drilling the well, the model is updated periodically as new information comes available. Predictive logs were generated from the geological model and serve as the reference point for correlation. The well data (trajectory, logs) were received in real time and incorporated on the fly into the geological model. This enabled fast decision making, with the potential to avoid costly drilling and geologic surprises and resulting in better control on well placement.

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