Abstract

This paper introduces a method for selecting the best sensor layout when using wired pipe for drilling operations. The introduction of wired pipe in drilling operations increases the data rate significantly compared to standard telemetry systems.

Various sensors systems are available, measuring parameters such as drillstring vibration, drillstring torque, downhole fluid temperature and downhole annulus pressure. Also available are measurements from various logging tools placed as a part of the bottomhole assembly.

The data from the sensors can contain important information that can be used for preventing various operational problems, such as high vibrations, insuffcient hole cleaning, kick incidents, and loss of circulation.

The method described in this paper can be used for designing a sensor layout for a wired pipe drillstring. The method analyzes data available from the sensors to yield the information required to detect operational problems.

The paper presents two different cases where the method is applied, one from a kick incident and the other from a loss of circulation incident. The results show that by optimizing the sensor layout for a wired pipe drillstring, cost efficient performance can be ensured with regards to potential drilling problems.

Introduction

During drilling it is important to avoid non-productive time. To avoid such situations, data can be gathered and used for extracting information about the well and the formation. Various types of sensors are being used during drilling operations, measuring different physical properties of the formation and the well.

One of the challenges during drilling operation has been to transfer data from downhole sensors to surface. The wired pipe drillstring has been used to provide large amounts of drilling data during the operation. In a wired pipe drillstring, a data cable is integrated into each pipe joint and has the possibility of transferring data from the sensors at the drill bit. In addition, data can also be transmitted from sensors mounted along the drillstring. The data cable gives the possibility of sending large amount of data from the sensors along the drillstring while the drilling process is in progress 1,2.

Various methods for automatic analyzing, presenting and evaluating the data has been examined, to be able to transform the data into information 3. A further evaluation of existing sensors and suggestion of new sensors and their placement should be performed. In production wells, an evaluation method for sensor selection and sensor placement with regards to predicting reservoir production rates has been developed 4,5.

The current paper focus on ranking the usefulness of various sensors when performing a drilling operation. The sensors selected in this paper are sensors that gives information about the fluid flow in the well, and the focus has been on pressure sensors and flow sensors. The temperature gradient between the well and the reservoir fluids are not included in the model, so the importance of temperature sensors should be further examined in a future study.

The paper is divided into five sections. In the next section a description of the theory regarding modelling and ranking methods is presented. Section three briefly presents two cases where the ranking method is applied. In section four the main results using the method are presented and discussed, and conclusions are given in section five.

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