Novel Carbon Reduction Calculations for Fracturing Completions Using Sleeves and Darts
Authors: Watkins Tom , Najafov Jeyhun , Watson Edward K. , Livescu Silviu 
Published: April 2023

Hydraulic fracturing is credited with making the United States immune to global energy disruptions and giving it one of the lowest electricity and fuel costs of all OECD nations. So important is fracturing that by 2015, more than two-thirds of all natural gas and more than one-half of all oil produced in the US came from fracturing (Energy Central 2018). One estimation is that electricity costs would be 31% higher, and motor fuel prices would be 43% greater without fracturing (Aardvark Packers 2019). Most fracturing uses the "Plug-and-Perf" method, where a wireline is used to plug a production well and position a perforating gun into the desired location to initiate fractures into the rock formation. This is then followed by pumping fracturing fluid to produce the fracture network that drains the reservoir's target zone.

A key problem is greenhouse gas emissions (GHG), also known as CO2-equivalent [CO2e] emissions, during the fracturing completion stage. This is because the machinery used to position the plugs and perforation guns, the post-frac work such as milling out the plugs, and the additional pumped water used in the pumpdown process require the combustion of diesel fuel, which produces GHG.

However, diesel combustion during completions is not the only source of GHG. To credibly quantify the amount of GHG produced due to completions, a cradle-to-grave assessment is needed. This includes considering the diesel GHG impact during:

Upstream operations (exploration and production), Midstream operations (surface processing and transport to the refinery inlet), Downstream operations (refinery production and the delivery of the diesel to the bulk terminal storage), and Delivery from the bulk terminal to the machinery on the well pad.

But this is not all. The plug-and-perf equipment also have a cradle-to-grave GHG effect – the mineral extraction and refining, production and assembly, testing and storage, packaging and transportation, handling and operation, and equipment end-of-life – all generate GHG.

This paper attempts to quantify the direct and indirect amounts of GHG associated with the plug-and-perf fracturing completion stage of one horizontal well while acknowledging that it is not possible to come up with a figure that takes all factors into account since the oil and gas industry is only at the initial stages of identifying and reporting the product carbon footprint (PCF) of all equipment and products associated with the industry. However, this attempt is very valuable, as the authors hope this study will trigger other researchers to quantify GHG for all oil and gas operations. The point this paper makes is that steps must be taken wherever possible to lower GHG given the severe impact of Environmental, Social, and Governance (ESG) on the oil and gas industry, where capital for projects becomes expensive or even nonexistent. Identifying areas of improvement can have an outsized impact on the success and even survival of a company, given current financial and regulatory trends. For instance, HSBC announced in December 2022 that it would no longer finance new oil and gas fields to pressure the industry to decarbonize (Yahoo Finance 2022). HSBC now joins Lloyds, Bank of America, Citi, JPMorgan Chase, Morgan Stanley, Goldman Sachs, Wells Fargo, and other Net-Zero Banking Alliance members committed to a carbon-neutral future. Since the Glasgow Financial Alliance for Net Zero started on April 21, 2021, its members now represent 41% of global banking assets or $73 trillion (UN Environment Programme 2023).

Given the ESG and the decarbonization challenges, this paper introduces a sleeve-and-dart solution to replace plug-and-perf that can reduce a company's GHG emissions by 95% for the first well and 76-77% for the second to fiftieth wells during the pumpdown period. For companies who prefer to continue using plug-and-perf, it identifies areas where significant CO2e reductions are possible.