Hybrid Power Generation At The Well siteKey Takeaways

Problem – Poor power quality leads to more downtime, lower equipment run-life and expensive incomplete solutions.

Solution – Smart energy storage delivers a comprehensive solution to combat power challenges that have long plagued the oilfield.

Results – Grid quality power at off-grid and grid-edge locations that lowers operating costs and improves oilfield operations and production targets.

Electrification of upstream operations is increasing as operators seek to maximize production, improve safety, and reduce costs, especially in mature fields. Operators have long tolerated poorly electrified oilfields, but times are changing and operators can no longer tolerate inefficient, tired and costly power solutions. Ever-increasing power demands at the wellsite are bringing power problems to a head. Energy is currently ~25% of Lease OPEX cost and this number is only expected to increase as operators continue to exploit complex shale formations. Increasing demand for energy will be the leading challenge facing operators by 2020. Wellsite power generation represents $1B dollar market where many of the new shale plays are still waiting on line power and rely heavily on generators. Oilfield generator power is ~$0.5/kWh, up to 5 times utility line power.

The oilfield has historically treated poor power quality as the cost of doing business. At the wellsite facilities and production engineers have historically had no other choice but to attack unreliable power with costly piecemeal solution that treat the symptoms rather than the root problem. These solutions typically involve additional CAPEX into high-end VFDs, harmonic filters, phase-shifting transformers and more power capacity whether additional gensets or grid upgrades. In places like the Permian, the oilfield is rapidly expanding and the grid simply cannot keep up. And so oftentimes operators are forced to delay operations and slow production. The oilfield requires flexible and scalable solutions that enable field expansions rather than hamstring it. Moreover, sensitive downhole and surface equipment requires IEEE519 grid-quality power. The distributed generation solution is one such method to facilitate reliable rapid oilfield expansion. Energy storage enabled microgrids with advanced software and energy management systems is one such method in delivering a cost-effective and reliable distributed generation solution.

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Figure 1: Lease OPEX at the wellsite

Power & Fuel 25%

Misc.%8

Labor6%

SubsurfaceMaintenance

4%

SurfaceEquipment

7%

Compression5%

Disposal32%

Treating 13%

In oilfield applications a small amount of energy storage combined with smart software and power electronics can be used to help optimize microgrid designs. Energy storage can be utilized to reduce generator capacity while helping those engines that remain to run more reliability, also helping to reduce maintenance costs. Energy storage can also strategically be deployed throughout a grid network to mitigate voltage, frequency and harmonic distortions. The ability to identify problematic areas on a grid and deploying energy storage at those specific locations allows operators to forgo costly grid upgrades and the typical 18 – 24-month timeline to accommodate for those upgrades. The strategic use of energy storage enables operators to drill and produce on their own schedule not on the power providers schedule.

Low oil prices are incentivizing producers to increase asset values by reducing non-productive time at the wellsite and by extending the time between workovers. As operators seek to optimize production in a cost-cutting climate, Schlumberger Artificial Lift Services has teamed with FlexGen to help operators choose the appropriate power system that best suits the field conditions to maximize asset value over the life of the well.

Emerging with the growing trend is a strategy for selecting the most appropriate power generation method to maximize production uptime and reduce costs associated with traditional power solutions. Rather than relying on guesswork, familiarity with a certain type of power solution or bias toward one method or another, production and facilities engineers are recognizing the benefits of using quantifiable field data to measure a field’s economic potential and develop a streamlined process for selecting an optimized power solution for the entire evolution of a field.

Figure 2: Permian Basin Production Site with SSG

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Engineering an electrification strategy that balances economic factors with specific well application and field considerations can be big win for exploiting reservoirs by extending equipment run life, reducing the cost per barrel of oil and boosting incremental production. A process designed to maximize artificial lift reliability and performance was implemented at a Williston Basin production site in ND.

Designed to simplify the process of selecting the power generation solution for a wellsite or field that best suits the operator’s objectives, the Schlumberger energy management service uses

available field data to evaluate the economics of competing power generation solutions. Power quality

and power availability are key considerations when selecting the optimal method of lift. As an example, some operators have shifted away from ESPs in favor or gas lift for artificial lift. Though ESPs offer wide flexibility and operating range over the life of the well while maximizing production output, poor power quality and limited power availability lead to production downtime and reduced equipment run life. These events force some operators to forgo the higher production output of ESPs and utilize gas lift in fields where gas is available. In cases where gas is unavailable, operators are driven to accept non-productive time in poorly electrified fields.

Schlumberger energy management services offer a variety of FlexGen power systems that are uniquely designed to enable operators to utilize the optimal method of lift enabling them to maximize production through reliable use of ESPs in fields where power has historically been problematic.

One case study in the Williston Basin of North Dakota focuses on an oilfield operator that selected ESPs as their method of artificial lift for a 6 well pad. Power quality issues alone at this specific site led to an average of 14 downtime events per month leading to 137 hours of cumulative downtime per month. The operator used ESPs from two leading ESP vendors, and all ESPs suffered from the same power quality issues.

The operator considered upgrading to higher end variable frequency drives (VFDs) to help correct power quality issues that were causing ESP downtime events. Past experiences showed that the investment in

such equipment did not always rectify the power problems leading to ESP downtime. Shifting to another less desirable method of artificial lift was also a consideration. After evaluating all available options to help reduce downtime, the operator decided to implement a FlexGen Solid State Generator (SSG) to help correct power distortions that would enable reliable ESP performance.

ESP downtime attributed to poor power quality

Figure 3: Williston Basin Production Site with SSG

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attributed to voltage distortions from 137 hours down to 4.8 hours per month. The FlexGen SSG also reduced voltage related downtime events by over 97%, saving an average of 422 barrels of oil per month. The FlexGen SSG capability to reduce total harmonics distortion (THD) helps reduce capital expenditures for production power systems. Many operators use higher end (more expensive) VFDs and or harmonics filters to help mitigate the harmful effects of THD. The FlexGen SSG makes a 6-pulse VFD perform like an 18-pulse VFD and eliminates the need for redundant equipment such as harmonics filters. The FlexGen SSG delivers clean, grid quality power to the ESPs, mitigating the harmful effects of THD on ESPs. The THD mitigation capability is also a contributing factor in extending ESP run-life. With the help of the FlexGen SSG, the operator at this Williston Basin site could reliability use 6-pulse VFDs without other harmonic reduction equipment.

The FlexGen SSGs maintained frequency in a tight tolerance, which led to decreased maintenance on the electric submersible pump motors while also decreasing their failure rates. The frequency regulation feature is a contributing factor in enabling reliable ESP performance. Improved frequency helps extend ESP run-life and maximize production uptime.

Operators can no longer afford to treat power as an afterthought at the wellsite. There are significant direct and indirect costs associated with unoptimized power system design and poor power quality. An understanding of the operators needs at the wellsite and throughout the field is essential to applying the appropriate power solution. Appropriately applied energy storage technologies in the oilfield can dramatically reduce costs associated with power while helping to maximize revenue.

Figure 4: Production Savings from SSG

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The FlexGen SSG was selected as the appropriate tool to support the 6 well pad, because it offered the most comprehensive power stabilizing solution. Schlumberger installed the FlexGen SSG at this Williston Basin production site in North Dakota. The FlexGen SSG stabilized power quality, preventing ESPs from tripping offline. The FlexGen SSG also prevented hard ESP shutdowns that typically reduce equipment life and thus extended time between workovers. The highest value driver for this operator, however, was the FlexGen SSG’s ability to maximize production output. The FlexGen SSG reduced downtime events

FlexGen BenefitsSSG reduced power related downtime by over 97%

Lost Production Savings w/ SSG1 = $85,625 / monthly

Voltage-Related Failures (Monthly)

1 Lost production calculated on 10.42 bbls/hr per well (6 wells) lost production at $60 bbl

150

100

50

0

Pre-Flexgen SSG Post-flexGen SSG

Stops Count Downtime (hrs)

14

137

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