Abstract

Real-time, downhole flow data is widely acknowledged to be of significant value for optimizing well and reservoir performance, particularly in high well cost, low well count developments and in complex multi-zone and multi-lateral completions. However, in the past, the availability and reliability of in-well flowmeters has not been at a level to justify their wide application. Within the past three years, a downhole fiber optic flowmeter has been developed, tested, and deployed in the field which overcomes these limitations.

This paper presents two case studies of field installations of the downhole fiber optic flow and phase fraction meter. The flowmeter contains no downhole electronics, is completely non-intrusive to the flow path, and has no moving parts, resulting in a high performance, high reliability system. Case studies of field deployments of the optical flowmeter in the Gulf of Mexico and offshore Trinidad are described. Aspects of the flowmeter installation, data analysis, system performance, and data application are discussed.

Introduction

Permanent downhole monitoring systems have become a standard component of many well completion designs, particularly in high well cost, low well count developments. While these systems have traditionally provided measurements of temperature and pressure, production and reservoir engineers have long recognized the potential value of real-time, continuous, downhole flow rate information. Applications for downhole flow data are numerous.

Well ramp-up.

Real-time downhole flow and pressure data allow completion and production engineers to better visualize and control well clean-up, reduce uncertainty in drawdown, and reduce the duration of the ramp-up period, thereby bringing the well on-line quicker and potentially at a higher rate.

Zonal production allocation.

In multi-zone completions, data from a downhole flowmeter can be used to allocate production from individual zones. This can be achieved either with a flowmeter placed above each producing zone or by installing meters between each zone and using total flow measured at the surface to obtain the contribution of the uppermost zone.

Identify and localize production anomalies.

One or more downhole flowmeters placed in the lateral section of a horizontal well can help locate production anomalies, such as which part of the lateral is contributing to flow and where water or gas breakthrough has occurred. This allows localized well stimulation or other well treatments to be performed to increase well productivity.

Direct determination of productivity index.

Real-time downhole flow rate and pressure data allows determination of a well's productivity index at any time without need for intervention.

Commingled production.

Regulatory agencies usually require production data from individual zones in a field. Reliable downhole flow data allows the potential to commingle production from multiple zones.

Reduce surface well tests.

Real-time downhole flow data reduces or eliminates the need for surface well tests to determine the productivity of individual wells. It also eliminates the human factor and safety issues associated with conducting monthly well tests and reduces the environmental impact of operations associated with well testing, such as gas flaring and water and oil handling and discharge.

Reduce surface facilities.

The ability to measure flow rates downhole may eliminate the need for a surface test separator, thereby significantly reducing the facilities requirements on offshore platforms.

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