Accurate, reliable, and repeatable flow rate measurements during well testing are critical for appropriate reservoir characterization. Recently, well tests have become shorter and more challenging, with the application of new interpretation techniques heightening the need for high resolution and more accurate flow rate measurements. Although conventional well test separators have seen significant improvements over the last few decades in separation efficiency, flow rate measurement accuracy, reliability and repeatability have remained immutable. Historically, the liquid outlets of most conventional well test separators were equipped with positive-displacement or turbine-type flow meters which are not typically tolerant of debris or solids in completion or produced fluids. This results in separators being bypassed during the initial clean-up or well-flow stages, creating gaps in flow rate histories. Additionally, flow rate measurements were greatly influenced by wellsite meter factor measurements (correction coefficients), which usually did not consider fluid type or separation efficiency. Coriolis mass flow rate meters can overcome these challenges. These meters are widely used in process facilities and highly regarded for their precision, accuracy, and simultaneous measurement of true mass flow and fluid density. However, their use in mobile and conventional well testing is still considered to be in its infancy, lacking an extensive track record and field operation experience. This paper will summarize the benefits and lessons learnt from using new-generation Coriolis-equipped well test separators in the North Sea over the past five years. Furthermore, a series of case studies are presented, in which data provided by these flow meters was critical for successful well test operations.

Perforation performance can be greatly reduced when encountering multiple casings where depth of penetration and crucially reduced entrance holes prevent effective gravel placement. A practically proven case study is presented on the design, equipment selection and execution of a successful cased-hole gravel-pack campaign in dual casing completions of an injector well. An integrated approach and workflow is implemented to enhance the gravel pack efficiency. It involves the combination of firstly, a high efficiency perforation system that optimizes tunnel geometry and penetration in a dual casing completion. Secondly, an innovative approach on the gravel pack installation using a viscous slurry to pump at slightly higher rates above the fracture gradient in order to create a small fracture around the wellbore. The success of the gravel pack installation is further assured by the application of an “alternate path” concept. Packing the perforation channels is achieved by selecting a big-hole gun system that provided optimal performance through the multiple casings including highly phased large casing exit holes resulting in a large area-open-to-flow. The cased hole gravel pack completions is installed using a high rate gel pack technique creating short, highly conductive fractures enhancing connection of the reservoir to the wellbore. Furthermore, annular pack integrity is achieved using an alternate path design ensuring uniform gravel placement over the sizable reservoir interval. Injectivity into the formation is proven via constant tubular and annular pressure; indicating minimal permeability impairment to the formation. The production zone is flow tested using an electric submersible pump with trace of solids 0.01% WT received at surface confirming the integrity of the gravel pack completion. With the increase of more complex reservoirs and completion techniques, practical application and solutions of such complexities add to the industry knowledge base. This paper shares a practical and proven integrated approach to providing solutions for installation of gravel pack in a dual-completions. This concept is based on many years of operational experience and lessons learned on the field.