Can we ever truly be improving pipeline safety? Despite operators’ best efforts, pipelines can only be completely safe with the aid of four things:
Of these four criteria, the first three fall under pipeline operators' complete control. Unfortunately, in this day and age, extensive pipeline information required for total safety is not always available. Many of the existing pipeline networks throughout the country are many decades old and, therefore, without suitable documentation to provide the information needed.
A Current Event Case Study
This ill-fated truth is likely the reason behind a recent incident in Colorado. This incident claimed the lives of two people. What happened? Earlier this spring, a flowline from an active wellhead was struck during construction activities within a subdivision north of Denver, Colorado. The severed flowline, shown in the picture at right, was a 1-inch-diameter line that had previously transported product to a tank farm north of the subdivision. This tank farm is no longer in service, and the flowline was to have been abandoned by its previous owner/operator. The Colorado Oil and Gas Conservation Commission (COGCC) is still evaluating whether proper abandonment procedures were followed.
Once cut, the flowline allowed a mixture of methane, ethane, and propane to saturate the soil surrounding the home — thus providing the fuel for the fatal explosion.
What Happened Next?
In response to this terrible incident, the Times-Call reports (photo credit: Dennis Herrera / Special to The Denver Post) that Colorado Governor John Hickenlooper issued a directive requiring oil and gas operators statewide inspect and pressure test all existing pipelines within 1,000 ft. of occupied buildings. They must also properly mark and cap any lines not in use, along with ensuring all abandoned lines are cut below the surface and sealed. While this is a great first step toward safety — and well within the industry’s best practices — the Colorado State Government then took things a step further.
The New Colorado Bill Intended to Help with Improving Pipeline Safety
The Colorado House of Representatives introduced a bill that would require oil and gas operators to give electronic notice to each local government in whose jurisdiction their pipelines are located. The notice must show the location of each flowline, gathering, or transmission pipeline that they installed, owned, or operated. Here are a few excerpts from the bill explaining things further:
“OIL AND GAS FACILITY" MEANS EQUIPMENT OR 10 IMPROVEMENTS, WHETHER SURFACE OR SUBSURFACE, USED OR INSTALLED 11 AT AN OIL AND GAS LOCATION FOR THE EXPLORATION, PRODUCTION, 12 WITHDRAWAL, GATHERING, TREATMENT, OR PROCESSING OF OIL OR 13 NATURAL GAS, INCLUDING FLOW LINES AND GATHERING AND 14 TRANSMISSION PIPELINES, REGARDLESS OF WHETHER LOCATED UNDER OR 15 NEAR A WELL PAD, TANK FARM, OR OTHER SURFACE FACILITY."
"OIL AND GAS LOCATION" MEANS A DEFINABLE AREA WHERE 17 AN OPERATOR HAS DISTURBED OR INTENDS TO DISTURB THE LAND 18 SURFACE IN ORDER TO LOCATE AN OIL AND GAS FACILITY."
In essence, the bill proposed mandated "well flowline mapping."
So What Does the Colorado Bill Mean for Pipeline Operators?
Not much, right now at least. If the bill had come to fruition, it would have been the nation’s first. However, it was stopped by a filibuster within the Colorado House of Representatives.
No matter which side of the political aisle you fall, it is hard not to see how mapping flowlines from wells (active or not) could be beneficial to public safety. Especially, in light of the recent incident here in Colorado.
It is still unclear how the flowline that inspired this bill — a flowline which lay seven feet below grade and six feet from the destroyed home’s foundation — was severed. But, the State of Colorado does not currently regulate the development (sewer lines and basements) over abandoned flowlines. Additionally, though information on oil and gas wells are clearly mapped and provided to the State of Colorado — the flowlines from these wells are not. Below is a map from the Denver Post showing the wells (including all producing, drilled, active, dry, abandoned, approved, and more) between North Denver and Fort Collins, which is the highest concentration of wells currently in the state.
Each of these wells has its own flowlines. As you can see, with this many wells, it could be very advantageous to have the associated flowlines mapped and made public. Naturally, the most efficient and effective way to have all those flowlines mapped would be through the use GIS and Esri tools.
How Could GIS Help Map Flowlines, thereby Improving Pipeline Safety?
GIS is the key to supporting flowline mapping per future state regulations. At the SSP Pipeline Practice, we believe that there are two options in which flowlines can be mapped within GIS. This is solely based on available historical documentation or survey data. If neither of these exist, it would be recommended to send personnel to the field to do above ground surveys of in connection points and flowlines to get X/Y coordinates.
*Note that the samples below show the location of the previous incident, but they are generalizations created by utilizing demo documents and data. They do not represent actual locations of the line.*
1) As-built or construction maps
a. Scanned image containing location of the flowline as it was placed in the ground
b. Image is georeferenced to the spatial location in the world
c. Flowline is digitized based on georeferenced image to create the polyline representation
2) Survey Data
a. Survey grade data is available from pre- or post-construction – X/Y point locations
b. The flowline is created based on survey X/Y locations
In addition to locating the flowlines via GIS (as shown above), we have also piloted projects by utilizing the Gas High Consequence Analysis, the same one that has been applied to the transmission pipeline industry. In these scenarios, we can utilize the Potential Impact Radius (PIR) calculation to determine if any structures or outdoor congregation areas could be affected by an incident. Using the logic below, we buffer the pipe to determine the impact radius, and then determine any intersection of structures within that defined polygon.
The potential impact radius must be calculated along the pipeline using the following formula:
PIR = 0.69 * (p*d2)0.5
PIR = Potential Impact Radius (in feet)
p = maximum allowable operating pressure (in pounds per square inch)
d = nominal pipeline diameter (in inches), and
0.69 is a constant applicable to natural gas (constants for other gases must be determined in accordance with Section 3.2 of ASME B31.8S-2001)
Food for Thought
Although intensive, this type of High Consequence Area (HCA) analysis would be very beneficial in predicting the outcomes of — and potentially avoiding — future incidents. We hope this article both provides a little more understanding on the current situation facing the oil and gas industry and promotes further efforts by operators to reduce pipeline risk. Although the law mandating this type of use did not pass locally, it provides a lesson in how we could create better safety by mapping flowlines and performing proactive risk calculations. I for one, imagine that this issue will not fade away any time soon.