Cost and Time Savings through Substation Integration in the Bakken

Authors: Jared Harris, Benjamin Hogenson, Pratap Mysore, HDR, USA

In recognizing the challenges for the Bakken, fast schedules, limited field staff, changing designs, and trying to remain cost competitive became evident that IEC 61850 would be a proper fit.  During brainstorming sessions, IEC 61850 appeared to provide a decrease in cost and construction time to bring substations online.  Over the course of the past 3 years this was proven by data that supports that IEC 61850 does provide a cost and time savings.  In addition, It also increases flexibility and reliability.
Historically, Rural America has always relied heavily on the Rural Electric Cooperatives to deliver power to its customers, and North Dakota is no different than that.  The majority of these North Dakota rural cooperatives have seen little to no growth over the course of twenty years.  However, the Bakken oil boom has forced many of these slow growth cooperatives into rethinking how they are developing their infrastructure. A key example of this is Mountrail-Williams Electric Cooperative.  In 2004, Mountrail-Williams had a maximum system load of 30 MW.  This load has increased to 300 MW in 2014 and is forecasted to reach 900 MW by 2018. The increase in loading has been driven mainly by large loads and services that are needed to support the oil industry, generally occurring after 2008.   Prior to 2008, Mountrail-Williams had relatively few substation projects, most of which were transformer change outs for 40 year old transformers.  Figure 2 shows the increase in substation projects from 2008 to the present year.  The majority of these projects and all the projects in 2012 were green field substations.

The Bakken oil field sprung up relatively overnight.  Between 2008 and 2012 the number of oil wells increased by over 700%. This increase was due to game changing technologies known as hydraulic fracturing (fracking) and horizontal drilling.  Fracking involves injecting pressurized fluids into rock to create pathways for the oil to flow through the different rock formations.  This drilling technology involves first drilling approximately two miles vertically and then two miles in the horizontal direction.  The oil formation contains four main layers that are being drilled.  They are the Bakken, the Upper Three Forks, the Middle Three Forks and the Lower Three Forks.  Currently some producers are drilling nine wells in every layer from each well location.  They are calling the well pads “super pads” due to the fact that 36 wells are placed on each site.  The density of the wells has caused a high level of electrical loading on the rural system.  Figure 1 shows the distributed loading across the Mountrail Williams System.

The wells themselves are the primary load.  However, the auxiliary loads have also created a demand on the electric utilities.  These auxiliary loads include; natural gas plants, compressor stations, pipeline pumping facilities, rail loading stations and electric drilling rigs.  The gas plants that have developed in the area vary in size from 7.5 to 70 MW loads.  Many of these gas plants originated as 7.5 MW but have added motor loads that increased the loading to 70 MW with short notice to the cooperatives on their plans to add load.  This has led to many challenges regarding substation and transmission line modifications to serve the load.  The compressor stations that have been created in the area are on average 10 MW loads and are used to force the gas to the gas plants for processing.  In one instance a single gas company sent out a notice that they planned to place a 50 MW gas plant accompanied by twelve 10 MW compressor stations and expected to have service in 12 months on all loads.  The compressor stations were spread over a 100 square mile area.  The pipeline pumping stations and rail facilities range from 2 MW to 10 MW loads and are used to move oil and gas from the area to areas of production and use.  Recently a few of the producers have started using electric drilling rigs. 
These rigs use up to 2.3 MW of load and are moved from site to site and have created a very diverse load. Figure 4 shows the load profile of an electric drilling rig over 90 minutes.

Another challenge that made IEC 61850 very beneficial was the rapid schedule of projects that were being driven by developers.  In certain cases critical large loads had an in service date of 12 months from the time of application.  With an average land acquisition and permitting delay of 6 to 8 months, this left little time to design, construct, test and commission the substations. In one example, the substation also changed from a four position ring bus with two 115 kV lines and two transformers to a six position hybrid design with four 115 kV lines, four transformers and distribution breakers.  This change occurred during construction.  The varying load requirements, sudden load requests, schedule variations and diverse nature of the load that has been created in the oil field has led to a drastically changing transmission and distribution network.  These challenges have led to a variety of substation revisions that have made IEC 61850 extremely useful.

Another challenge unique to the oil fields was the limited number of contractors.  At one time the Associated Press pointed out that the rent in the town of Williston, ND for a 700 square foot, single bedroom apartment was renting for $2,394.  Although many oil companies are willing to pay top dollar for a work force, rural utilities need to assure quality, cost and consistency. 
Therefore, the number of quality wireman and electricians that were available to support construction were reduced to two certified contractors and their staff.  This decrease in wireman limited the ability to support construction and required an expedited construction schedule.

Power. Flexible. Easergy.
BeijingSifang June 2016