Jeff Saponja - Oilify
Ritthy Son and Thomas Vest - Diamondback Energy
Today’s horizontal wells target deep reservoirs and produce high gas-to-liquid-ratio fluids that are often solids-laden. Long, undulating laterals cause gas, liquid, and solids to arrive at the artificial lift system as complex, inconsistent slug flows. As a result, downhole gas and solids separation systems must perform at a much higher level—while still remaining low-cost to run and low-risk to retrieve.
For decades, downhole gas and solids separators for artificial lift were built from metals. Metals handled depth, temperature, pressure, corrosion, hydrocarbons, solids, and wellbore deviation. Non-metallic fiber-reinforced composites (FRC’s) generally could not. Their use stayed narrow: fiberglass sucker rods for weight reduction, thermoplastic sucker rod guides for abrasion control and thermoplastic plastic lined tubing for abrasion/corrosion control.
FRC’s have advanced considerably in recent years. Strength, quality, hydrocarbon tolerance, additive manufacturability (i.e., three-dimensional printing) and affordability makes them attractive for improving downhole separation. Additional breakthroughs in hybrid metal-to-FRC construction have opened new options for higher separation performance at lower risk and lower cost.
Two new downhole separators were developed to take advantage of hybrid metal-to-FRC advancements:
1. A packerless liquid-fallback gas separator with improved performance, lower cost, and lower retrieval risk over existing designs.
2. A large capacity slug-flow tolerant solids separator that integrates directly with the highly successful, widely adopted, extended dip-tube bottomhole assemblies (BHA’s).
A hybrid metal-to-FRC packerless liquid-fallback gas separator was designed to improve separation efficiency while reducing retrieval risk. Non-structural, serviceable, larger-OD body parts were made from FRC so they readily mill out if stuck. Metals parts provided structural strength and mechanical performance. Cost was lowered by using off-the-shelf parts: HPHT fiberglass composite surface facility pipe for the shroud and a sucker rod for the backbone.
A cost-effective high-capacity, slug-flow-tolerant multi-stage solids separator was built with three-dimensional printed thermoplastic FRC internals inside standard metal tubing joints. Staged separation effectively breaks up solids slugs at the BHA and then isolates them in segmented containment, out of harm’s way before the pump.
Field implementation is demonstrating a 50 percent larger upward facing separator intake area (for the same body outside diameter) over existing designs has improved gas separation efficiency, at 50% lower manufacturing cost, and with the lowest retrieval risk. Metal-to-FRC solids separation has improved substantially over metal-only solutions, as shown by improvements in pump run lives.