Flow Assurance Instrumentation
Authors: Kutlik Roy , Allen John 
Published: October 2008

Flow Assurance in production systems is critical to their successful and economic operation. In deepwater, the deep and cold environment is more challenging than that encountered in most producing environments. New management and remediation techniques have to be developed to reliably, efficiently, safely and economically handle the deposition problems of hydrates, waxes, scales and aspaltenes. New sensors and data collection systems are being developed to monitor the deposition accumulation as it occurs. Real time monitoring provides two potential benefits. They are:It is possible to actually quantify the performance of deposition management techniques and to validate deposition simulators in service. Previously, this has not been possible and field trials of these techniques have been time consuming and expensive. This monitoring capability allows for rapid evaluation of new deposition management technology.Monitoring routine production operations will provide an early alarm to field personnel alerting them to a developing deposition problem before it develops into a serious problem. Operating personnel can respond to and correct the situation creating the deposition.

Sensors and real time instrumentation for Flow Assurance are currently emerging. New technologies like fiber optic sensors, multiphase meters and acoustic thickness sensors are being incorporated into a prototype field monitoring system. This prototype system will be for DeepStar's experimental use in the winter 1999 field tests. The performance of this prototype will show the benefits and need that exists for real time Flow Assurance monitoring in the deepwater production industry.

Introduction

As offshore fields are being developed at increased step-out distances, the issue of "Flow Assurance" has attracted increasing attention within the oil industry. Flow Assurance addresses the problems of solid deposition of waxes, hydrates, aspaltenes and scales within the well-bore., flowline and riser and the techniques to minimize the effect of these deposits on production. The problem falls into two categories: knowing which deposits have formed and improving ways to manage the deposits. Deposition management can be achieved in three ways: mechanical removal of the deposits by pigging, chemical treatment of the deposits, (both in inhibit and to remove deposits) and thermal techniques top prevent deposits forming. All three techniques are expensive, and optimization of flowline management offers potentially massive savings to Operators. In order to do this, it is necessary to know what deposits have formed within the flowline and their location. This information can be gained by measurement of actual deposits or measurement of process parameters, principally temperature and pressure and using this information to model the deposition chemistry within the flowline. Due to the length of most flowlines, making sufficient discrete measurements along the flowline is not feasible and is generally limited to measurement at the outlet (platform end) and more recently at the "downhole" and wellhead site. Distributed, or quasi-distributed, measurements are required to accurately define deposition characteristics along the pipeline. At the current time it is not possible to make distributed measurements of the actual deposits, hence distributed inferred measurements are necessary.