Cost Effective Solution for Liquid Loading Elimination & Ensuring Production Sustainability

Abstract

A cost-effective solution for liquid loading elimination and ensuring production sustainability was needed.

A liquid loading issue was identified by a client in UAE in one of their gas wells. Market scanning was conducted looking for a viable solution that could be implemented across fields. Liquid loading occurs when the gas velocity is insufficient to carry the produced liquid to the surface. The accumulation of the liquid in the wellbore produces astatic liquid column causing a decline in the well production or prevents it from producing over time.

A velocity string, a small-diameter tubing string run inside the production tubing of a well as a remedial treatment, was selected as a solution for this well. The velocity string works by reducing the flow area and increasing the flow velocity to enable produced liquids to be carried to the surface.

An evaluation of revised well performance was carried out for the gas-producing well before installing a velocity string in it. Well production data, fluid properties, and reservoir details were collected and production modeling through various sizes of velocity string was performed. It was deduced that a string with an outer diameter of 2.375-in. would provide a stable production rate minimizing periodic coiled tubing interventions. To overcome reduced fluid capacity through the velocity string, a sliding sleeve door was installed to allow annular flow enhancing the overall production volume.

The installation was performed by hanging the velocity tubing string with a thru tubing hanger inside the production tubing without the need to kill the well which eliminated formation damage issues.

The velocity string completion design allowed for accessibility to the existing safety valve, and it provided landing profiles for the installation of deep barriers or gauge hangers in the well in the future.

The well was put under production through the tubular section for its performance evaluation and the annular production through the sliding sleeve door was considered based on the evaluation.

The velocity string extends the continuous production life of the mature wells before plug and abandonment, or expensive workover operations are executed. Currently, the well is producing without any intervention for more than 16 months. Successful trial of the velocity string system in this candidate well as an economical and minimal footprint solution can be implemented across fields.

It also avoids any formation damage which occurs during well killing as velocity string installation is a live well operation and is a solution that can be designed to suit any well with various well environmentexperiencing liquid loading issues.