Real-Time Evaluation of Kick during Managed Pressure Drilling based on Wired Drill Pipe Telemetry
Authors: Gravdal Jan Einar 
Published: May 2016

Wired drill pipe telemetry is expected to revolutionize the ability to transmit downhole measurements in real time during drilling operations. Bandwidth, reliability and availability improves dramatically and lead to better premises for developing new technology for more advanced drilling methodology. Specifically, distributed pressure sensors along the drill string, combined with real-time analysis of the data at the rig, will give valuable information to the drilling control system and the decision makers when utilized properly.

In this paper, improved methodology for kick evaluation and handling during Managed Pressure Drilling is presented based on this step change in availability of downhole pressure measurements. The objective of this methodology is to improve Managed Pressure Drilling by better handling of unwanted influx from the formation and thereby reducing formation damage and non productive time.

The presented methodology relies on the characteristics of the pressure curves from distributed sensors during a kick. A representative North-Sea well is used as test case geometry and an advanced hydraulics model is used as a virtual well in computer simulations that provide the basis for the presented results. The proposed methodology is demonstrated to estimate the depth of the influx zone as well as the size and distribution of the kick. This will improve the handling of the influx, prevent the risk of hole stability problems and the cost associated with non-productive time.

Introduction

Throughout the history of hydrocarbon drilling, various methods have been developed to detect unintended flow interaction between well and formation as fast as possible to take immediate action and handle the problem. Still, pit gain or loss, and unexpected deviations in pump pressure, are used as primary indicators for kick or lost circulation. However, for long wells and in particular High Pressure High Temperature wells, these indicators may be too rough for fast and precise detection of small and moderate volumes. Accurate flow sensors at the outlet, such as coriolis flow meters, have been used for faster detection of kick or lost circulation the last few years in Managed Pressure Drilling (MPD) operations [1].

The latest improvements on data transmission from downhole sensors during drilling may lead to a new era in kick and loss detection and evaluation. The request for more information from the well and direct access to down hole tools during the drilling operation has enforced the development of the wired drill pipe telemetry system. Bi-directional real-time drill string telemetry at high speed is now available and may be capable of transmitting data of up to 2 Megabits/sec in the near future [2], [3]. High speed bandwidth from sensors down hole during the entire operation (not only when circulating) and two-way communication with down hole tools may revolutionize the drilling operation. Wired drill pipe telemetry also enables distributed measurement nodes along the drill string. This will improve the driller and decision makers' ability to make better and faster decisions if adequate data handling software is being used. Altogether, the wired drill pipe technology opens up for more extensive use of real-time or quasi real-time systems for automation and decision making. In this context the term automation implies adding intelligent software agents into the control systems that handle downhole tools (e.g. rotary steerable) or rig equipment (e.g. mud pumps, draw-works, top drive or chokes) [4], [5]. Improved down hole data quality and reliability will improve the new diagnosis and decision support systems that are being developed today. These systems utilize available downhole measurements together with operational parameters and aim to assist the decision makers with real-time analysis and decision support [6]-[9].