Citation: Ouadi, H.; Laalam, A.; Hassan, A.; Chemmakh, A.; Rasouli, V.; Mahmoud, M. Design and Performance Analysis of Dry Gas Fishbone Wells for Lower Carbon Footprint. Fuels 2023, 4, 92–110. https://doi.org/10.3390/ fuels4010007 Academic Editor: Nashaat Nassar Received: 16 January 2023 Revised: 5 February 2023 Accepted: 24 February 2023 Published: 27 February 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Article Design and Performance Analysis of Dry Gas Fishbone Wells for Lower Carbon Footprint Habib Ouadi 1, * , Aimen Laalam 1 , Amjed Hassan 2 , Abderraouf Chemmakh 1 , Vamegh Rasouli 3 and Mohamed Mahmoud 2 1 Department of Petroleum Engineering, College of Engineering and Mines, University of North Dakota, Grand Forks, ND 58202, USA 2 Petroleum Engineering Department, College of Petroleum Engineering & Geosciences, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia 3 Department of Energy & Petroleum Engineering, College of Engineering and Physical Sciences, University of Wyoming, Laramie, WY 82071, USA * Correspondence: habib.ouadi@und.edu Abstract: Multilateral well drilling technology has recently assisted the drilling industry in improving borehole contact area and reducing operation time, while maintaining a competitive cost. The most advanced multilateral well drilling method is Fishbone drilling (FbD). This method has been utilized in several hydrocarbon fields worldwide, resulting in high recovery enhancement and reduced carbon emissions from drilling. FbD involves drilling several branches from laterals and can be considered as an alternative method to hydraulic fracturing to increase the stimulated reservoir volume. However, the expected productivity of applying a Fishbone well from one field to another can vary due to various challenges such as Fishbone well design, reservoir lithology, and accessibility. Another challenge is the lack of existing analytical models and the effect of each Fishbone parameter on the cumulative production, as well as the interaction between them. In this paper, analytical and empirical productivity models were modified for FbD in a dry gas reservoir. The modified analytical model showed a higher accuracy with respect to the existing model. It was also compared with the modified empirical model, which proved its higher accuracy. Finally, machine learning algorithms were developed to predict FbD productivity, which showed close results with both analytical and empirical models. Keywords: Fishbone well; well productivity; analytical model; empirical model; data-driven models 1. Introduction A multilateral well configuration encompasses the deployment of multiple horizontal laterals branching off from a singular vertical wellbore, with the objective of enhancing production efficiency [1]. The utilization of multilateral wells aims to increase the drainage area and thus augment the production rate [2]. Although the drilling cost associated with multilateral wells may be higher, this cost is offset by the improved reservoir recovery resulting from enhanced wellbore-reservoir contact. There has been extensive research directed towards optimizing multilateral drilling costs and designs [3,4]. One of the latest advancements in multilateral drilling technology is Fishbone Drilling (FbD) [5]. FbD is comprised of a series of micro-branches drilled in divergent directions from a primary horizontal wellbore, with a designated inter-branch spacing as shown in Figure 1 [6]. The implementation of FbD can maximize reservoir contact area and facilitate access to previ- ously unreachable geological formations, thereby augmenting cumulative production [7]. FbD has been shown to have higher productivity compared to hydraulic fracturing in rela- tively low permeability formations [8]. FbD is a desirable solution in the light of economic, environmental, and regulatory limitations [9]. A recent study conducted by THREE60 Energy found that Fishbone drilling methods result in significantly lower CO2 emissions Fuels 2023, 4, 92–110. https://doi.org/10.3390/fuels4010007 https://www.mdpi.com/journal/fuels