套管钻井

SPE-158245-PP

Electromagnetic Measurements While Drilling: A Telemetry Solution for Casing While Drilling

M Zarir Musa, Dian Semesta Bt Abdul Aziz, Heru Hermawan and Trigunadi Budi Setiawan, Petronas, Ilen Kardani, Mohd Azlan Shah Askar Ali, and Rosli Sidek, Halliburton

Copyright 2012, Society of Petroleum Engineers

This paper was prepared for presentation at the SPE Asia Pacific Oil and Gas Conference and Exhibition held in Perth, Australia, 22–24 October 2012.

This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of SPE copyright.

Abstract

Casing-while-drilling (CWD) operations have become a well-known technology used to minimize drilling time and reduce the AFE budget. A major oil and gas company has drilled several wells in Malaysia by using this technology, which has proven to be a cost-efficient strategy, particularly in the batch drilling process.

Past CWD operational experiences have demonstrated stark differences when compared to conventional drilling in terms of wellbore surveying and formation evaluation. Weak and noisy signals from mud-pulse telemetry specific to the CWD environment were primary issues that required a significant amount of rig time when acquiring measurement-while-drilling (MWD) and logging-while-drilling (LWD) data.

In fact, several significant challenges were encountered. First, the mud-pulse signal, which traverses from downhole (MWD) to the surface, somehow dampened out. Although various types of mud-pulse telemetry systems have been used, significant problems remain. In addition, the signal transmission worsened when seawater was used as the drilling fluid, resulting in non-productive time owing to the provisioning of change-out tools with different configurations for mitigation and trial-and-error purposes. Finally, overall drilling efficiency was reduced as a result of poor signal detection and capturing.

Electromagnetic (EM)-MWD used in combination with gyro-while-drilling (GWD) was identified for implementation when drilling four wells using Tesco CWD technology in the Erb West field. The mud-pulse and electromagnetic telemetry systems were executed as a pair to compare captured signal strengths in the same environment (i.e., directional CWD with seawater drilling fluid).

After drilling ceased, the generated results proved that EM-MWD is a viable technology that can be used to overcome signal attenuation issues in a CWD operation. Most importantly, such application reduced rig time by 3.9 days, which contributed to 26% of the cost saving for the surface section drilling by having trouble-free MWD signal detection and faster drilling operation. It also minimized health, safety, and environment (HSE) risks by reducing the time spent on rig activities, as well as established a working model of EM-MWD-CWD.

Introduction

The Erb West field is situated offshore of Borneo, about 80 km to the northwest of Kota Kinabalu, the state capital of Sabah, East Malaysia (Fig. 1). The field is operated by a major oil and gas company in Carigali Sdn. Bhd. as a subsidiary of Petroliam Nasional Berhad. The Erb West general structure consists of a domal NE-SW trending anticline divided in four fault blocks by three major east-west trending faults.

The main prospective sequences, the N sands containing the main part of the oil reserves, are deposited in a shallow marine environment in the Middle Miocene. The intercalation of the sand and shales is clearly visible on the log shown in Fig. 2. The shales separating the sands are generally continuous field-wide. As of 2012, a total of 48 wells have been drilled, inclusive of the latest revisit program rolled out at EWDP-B.

Project Challenges

In developing brown fields, the most common challenge is the selection of a cost-effective and low-risk technology. Therefore, the main objective given was to significantly improve total field production while minimizing the drilling budget use without jeopardizing HSE and wellbore quality.