Data Driven Total Systems Analysis Leads to Successful Treatment of Severe Calcium Carbonate Scale in the Delaware Basin Avalon Formation

Abstract

There has been a recent shift in the Permian across unconventional frac targets in the Delaware Basin stacked play. Operators are now targeting shallower zones, such as the Avalon formation. When comparing key scale risk drivers, such as brine compositions and mol% CO2 of the Avalon formation to more traditional targets such as the Wolfcamp and 2nd & 3rd Bone Springs, not only does the Avalon present its own unique scaling challenge, but the commingling of these formations can present a much greater scale control challenge. Previous work highlighted the Avalon formation's high natural potential for carbonate scale precipitation, which aligns with field history presented here. These unique challenges will play a part in the next wave of formation-based proactive chemical treatment strategies across upstream, midstream and water disposal systems. Here we present a case of severe carbonate surface scaling from Avalon formation brines. The operator was experiencing calcium carbonate scaling on flowlines, water legs of separators, and equalizing lines between water tanks every 3 to 4 months. The operator had to choose between using heater treaters in winter to sell oil or scaling off the heaters. Incumbent service companies had successfully controlled downhole scale but could not control the surface scale issues. A total systems analysis including field analysis, scale modeling, 21 produced fluid chemical compatibility experiments run across 11 different scale inhibitors, minimum effective dosage (MED) identification through 119 NACE static/synthetic brine and Dynamic Scale Loop (DSL) testing was performed to identify a solution. The solution highlighted in this paper resulted in zero facility scale-offs (26-month treatment period to date of publication), use of heater treaters in winter to sell oil, and operational efficiency gains in reduced manpower for cleanouts. Additionally, the ability to now commingle high-risk brines at central tank batteries allowed for the decommission of small satellite facilities previously used to isolate the highest scale risk brines. The Avalon is not a new target but is projected to become more common in the future. The recent shift has implications to change how, where, and why we treat for carbonate scale in the Delaware Basin.