Artificial Lift

Extended-reach horizontal well geometries and higher hydraulic fracturing stage counts have led to increased well productivities in tight oil plays across the Lower-48. However, lateral lengths in excess of 10,000 feet with complex fracture networks can also introduce more dynamic behavior and even more severe production declines over time, often exacerbated by tight oil formations that produce fluids with higher gas-to-oil ratios, sand and solids content, and water cuts. 

QSO Inc. has developed a product to provide a unique and simple solution to problematic or inefficient plunger lift systems installed in horizontal wells in the USA. QSO’s Patented* Horizontal Check Valve (HCV) has removed the limitations that once burdened the industry in not being able to hold fluid properly in a horizontal well. Our HCV has proven to hold fluid in wells where conventional check valves start failing.

This paper will cover sucker rod pump barrels that are available in the industry for downhole sucker rod pumps, as well as tapered barrels for pressure balance on the upstroke.  For barrels it will cover their traditional uses, interesting exceptions to API 11AR recommendations, barrel materials and their applications, and tubing anchor effects.  The theory behind a new tapered barrel pump will be covered, as well as the materials used, a unique testing apparatus and the advantages to the operation of the well. 

To deal with gas and sand problems in their conversion and rod pump wells an operator company in south Texas started introducing a combined technology of two-stages filtration with a modified poor boy gas separator obtaining excellent results. This paper explains the technology used and shares the information used to design the tools and the results achieved in the first wells completed. The screening process to choose the best technology started by trying different technologies for gas and sand control below the rod pump.

Rod pumping horizontal wells is more complicated and challenging than for vertical wells. For system reliability reasons, it is common for horizontal wells to have a rod pump placed in the vertical section above the wellbore’s curve, which limits drawdown. This means the pump is placed a vertical distance above the producing zone and a pressure gradient of fluid between the pump and the producing zone exists. This pressure gradient can add 200- 500 psi of back pressure to the producing zone, limiting drawdown.

Rod pumping has been challenged by solids contained in produced fluids, as they reduce pump run-life. For horizontal wells solids risks have dramatically escalated, as hydraulic fracturing has exponentially increased in terms of number of stages and the amount of proppant pumped. EOR schemes can also escalate solids in produced fluids. To combat solids in the produced fluids reaching a pump, control methods have included solids separators and filtering screens. Both methods have realized limitations and therefore have not effectively resolved solids risks to acceptable levels.

The effect of traditional chemical treatments at the pump intake can be minimized due to the fluid level, high GLR, and production packers, among other reasons. Using a slow-release polymer matrix is an effective chemical treatment that was installed in several wells in the Delaware basin with Conoco Phillips. The chemicals were encapsulated in the matrix ensuring maximum absorption and then slow dispersion, and the tool was run under the intake of rod pumps, and gas lift.

Slow strokes per minute, open pump clearances in a deep well have impacted the shape of the pump card and frequently results in the question: "Is my tubing unanchored?".  The Coefficient of Tubing Stretch, Kt, and the downhole pump dynamometer card can be used to help identify unanchored tubing.  The Unanchored Kt and Anchored Kt lines plotted on the left side of the pump card shape are the first step in resolving if tubing is anchored.

OBJECTIVES/SCOPE:

Design and analysis of sucker rod systems in deviated wells has challenged industry practitioners. Historical adaptations of the wave equation solution struggle with 3-dimensional wellbore trajectories and other system complexities. A unique finite element model, embodied in an easy-to-use software, simulates rod-dynamics in 3 dimensions. The model can predict or analyze motion of the rod string at any location in the well. Frictional forces and buckling tendencies are also simulated.