Study Explores Cost-Effective, Ecologically Sound Fluid-Disposal Methods

Abstract

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 202917, “Cost-Effective and Ecologically Sound Fluid Disposal During Well Cleanup and Post-Fracturing Flowback Operations,” by Yakov Shumakov, Florian Hollaender, SPE, and Bertrand Theuveny, SPE, Schlumberger. The paper has not been peer reviewed. The complete paper summarizes the results and lessons learned from the application of different methods used for fluid disposal in a wide range of well-testing operations around the globe. These were used to determine that economical and environmentally responsible solutions exist for fluid disposal during these operations. The complete paper also details a field-proven and cost-effective fluid-storage solution using a shuttle tanker during well-test and flowback operations offshore. Fluid-Disposal System Ecologically sound and safe fluid disposal during well testing and cleanup is one of the primary objectives, from an operational standpoint, of any temporary surface well-test package. Each fluid-disposal system is designed and sized for each operation according to the expected operating conditions. Typical fluid-disposal systems include the following. Water-Filtration System. In this system, produced water is first separated from hydrocarbons at the surface by using the well-test separator included in the temporary surface package; then, it is treated to remove as much oil as possible before discharge overboard. Even after effective treatment, however, produced water still contains traces of oil at parts-per-million levels. Overboard discharge of any kind is controlled strictly by environmental regulators and legislation. The primary pollutants of concern are hydrocarbons and grease; therefore, most treatment technology for water produced offshore is geared toward removing these contaminants. Mobile water-treatment systems are ideal for fast-response or urgent situations, as well as supplemental or temporary operations such as completions, workovers, or well testing. They are often used to assist during plant startup and maintenance outages when the water-treatment system is unavailable or cannot meet water-production requirements. Temporary Fluid Storage. Provisional storage of produced hydrocarbons has been used successfully in the past and is still considered an optimal solution for operations with a relatively small volume of liquid hydrocarbons produced. In offshore operations, one important factor beyond the space on the deck of offshore rigs is the limit on the volume of live crude that can be stored permanently on the rig. The limitation in recoverable liquid volume applies a significant constraint on the duration of the test; thus, this disposal technique is applicable mainly on gas wells and in environmentally sensitive areas.