The American Oil and Gas Reporter - January 2012 - (Page 177)

Production Technology Sand-Plugged Wells Get Chemical Help By Grant Williams and Travis Minish NORTH BATTLEFORD, SASKATCHEWAN–New chemical dispersant technology designed to reduce the apparent viscosity of low-gravity crude oil in the well bore is revitalizing heavy oil wells in west-central Saskatchewan. The system increases recovery rates without thermal assistance and drastically lowers operating costs by achieving step-change improvements of sand management. The new chemical process was deployed for the first time during 2011 at a dozen wells producing 10 degree to 15 degree API gravity crude from Mannville Group formations in the Lloydminster region of Saskatchewan and Alberta. Most dispersant applications have been applied at wells exhibiting unexpectedly low rates of production, requiring excessive servicing and maintenance intervention, and/or experiencing high rates of equipment failure, but some operators have begun using the technology at new wells. When the dispersant chemistry is mixed with water and injected down hole, a water-external macroemulsion (or dispersion) is created in the well bore. The resulting water-wet film prevents the heavy oil from adhering to rod string, pump or production tubing surfaces. Reservoir fluids and sand entering the downhole pump are dispersed more easily in the water-external macroemulsion, and are lifted to the surface more reliably. In turn, the steadier flow eases the stress on pumping assembly components. If an operator wants his production to qualify as clean crude and thereby save money on treatment costs, he can inject a conventional emulsion breaker into the production stream at the surface as it exits the wellhead and enters a flowline leading to the production tank (Figure 1). Heavy oil wells treated with the chemical dispersant technology have responded with reductions in pump torque of more than 50 percent; increases in well operating speed of greater than 100 percent; less sand accumulation in production equipment and flowlines; less downtime while awaiting service or maintenance; and incremental production gains amounting to several orders of magnitude. Residual derivative chemicals in sale oil have proven to have no discernable effects on separation facilities. With treatment costs averaging $2.00 a barrel of incremental production gained in the limited applications to date, the sum of benefits achieved by the new chemistry has consistently transformed economically marginal wells into reliable, profitable producers. In one instance, treatment with the dispersant chemistry allowed the owner to delay plans to plug and abandon a low-volume well. Sales oil volumes increased following treatment, but documenting a production increase is difficult because sand-induced failures during the previous five years make production records virtually useless for analytic purposes. CHOPS Challenges Producing heavy oil is a costly and capital intensive endeavor the world over. The best-known methods of recovering heavy oil efficiently and reliably in western Canada have focused mostly on surface mining techniques and thermal recovery methods, such as steam-assisted gravity drainage and in situ fire flooding. However, operators in the Lloydminster area have been implementing so-called cold heavy oil production with sand (CHOPS) processes since at least the early 1980s. With only about 13 percent of the province’s original oil in place estimated by the Saskatchewan Geological Survey to be recoverable using current production methods–and based on expected economic FIGURE 1 Surface Equipment Setup Production Tank (750 bbl or 1,000 bbl) L conditions–the potential is great for the CHOPS techniques and enhanced oil recovery methods. The task of profitably implementing CHOPS techniques is impaired by a number of challenges, principally stemming from the high viscosity of the crude to be recovered, which has ranged as high as 130,000 centipoise (cP) in some of the wells treated with the new chemical dispersant technology Production problems in CHOPS wells can arise when the progressive cavity pumps capable of handling high-viscosity fluids, which are chosen as the main pumping method in most cold-recovery systems, encounter severe oil/water slugging and production of unconsolidated solids from the reservoir. The highly variable loads resulting from shifting solutions of oil, water and sand cause heavy fluctuations of torque on pumping assemblies. Oiland-water slugging also makes it difficult to fill the pumps with oil, as the free water migrates through and around the heavy oil, leading to high basic sediment and water content of produced fluids. In the Manville Group’s heavy oil reservoirs, highly viscous crude also drags with it large amounts of sand from unconsolidated sandstone intervals, leading to pump erosion, higher torque requirements, and sand settling/packing in and near the well bore. Sand accumulates in production components and in flowlines connecting wellheads to tank batteries, leading to high rates of equipment failure, Flowline to Tank L L L Water/Oil Separation L L L Water Injection Pump Water Injection Line Chemical Pump Chemical Tank JANUARY 2012 177 L Wellhead

Table of Contents for the Digital Edition of The American Oil and Gas Reporter - January 2012

The American Oil and Gas Reporter - January 2012
Oil & Gas Counts
State Legislative
Industry Digest
Tech Connections
Washington Watch
Federal Legislation
Gulf of Mexico
Resource Plays Providing Wealth of Opportunities
Tight Plays Poised to Transform U.S. Crude Supply
El Paso Project Optimizes Eagle Ford Completion Design
Real-Time Forward Modeling Improves Bakken Horizontals
Cover Story
Financial Firms Expand Oil and Gas Divisions
Multicomponent 3-D Poised for Growth in Shale Plays
Cloud Computing Driving Business Step Changes
Advanced Attributes Improve 3-D Interpretation
3-D Data Improve Knowledge of Shale Heterogeneity
HBUR RSS Solves Granite Wash Drilling Challenges
Technologies Improve Production Consistency in Resource Plays
SaaS Helps Operator Streamline Data Management
Automation Enhances Operations in Challenging Applications
Dispersant Chemistry Combats Plugging in Low-Gravity Oil Wells
New Technologies Optimize Production
Drilling Regs
The Presidential Papers
Energy Education
Shale Gas
New Lits & Products
Computer Currents
Industry Focus
Classified Advertising
Advertisers Index

The American Oil and Gas Reporter - January 2012