# Evaluation and Economics of Shale Gas Reserves in the Flysch-Eocene Formation of the Jaca Basin
## 5 Conclusions  
The recent increase in energy prices is making European consumers vulnerable. In order to face the new international scenario of the gas sector, it is convenient to estimate its own exploitable reserves, including hydraulic fracturing technology.  
Spain has the capacity to use hydraulic fracturing technology to supply itself with natural gas. Although consumption would still be much higher than existing reserves, a complementary domestic natural gas extraction industry can be generated, reducing foreign dependence on other countries.  
The Jaca Flysch site is one of the possible sites that can be exploited in Spain. Its possible exploration and exploitation are restricted by Law 7/2021, of 20 th of May, on climate change and energy transition, which expressly prohibits the exploration and extraction of hydrocarbons [21].  
The average production proposed in this study would make a significant contribution to the energy mix and would represent between 10% and 20% of national consumption for several years, highlighting the potential in areas similar to the Jaca basin to increase natural gas production by around 48% through the use of hydraulic fracturing.  
This technology is in question due to the consequences on the environment if the environmental risks involved are not effectively managed [56]. However, there are procedures and best practices that can help manage and minimize these risks [20], even if it means increasing the cost of a typical well by 7%.  
This study proposes a series of actions to ensure sustainable development of Flysch exploitation as it is considered that public confidence in the safety of hydraulic fracturing would be greatly improved by more frequent microseismic monitoring and public dissemination of the results. The establishment of an independent Well Examiner to guarantee the integrity of the wells, verifying through reports the correct design and drilling system, is also proposed.  
It is concluded that it is possible to carry out a profitable and sustainable production of natural gas with hydraulic fracturing technology in Spain, limiting the study to the Jaca Flysch, so that it is possible to continue using natural gas as part of the energy mix, contributing to the transition and the reduction of the energy dependence on other countries.  
Conceptualization, L.M.V.-F, C.G.-O. and E.Z.-T; supervision, L.M.V.-F. and C.G.-O.; validation, L.M.V.-F, C.G.-O. and R.R.-P.E.; writing--original draft, L.M.V.-F, C.G.-O. and E.Z.-T.; writing--review and editing, L.M.V.-F, C.G.-O. and R.R.-P.E. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Oil and Gas Engineering Master's degree (mip) of the Universidad Politecnica de Madrid (UPM), which is taught at the Escuela Tecnica Superior de Ingenieros de Minas y Energia (ETSIME).  
Not applicable.  
The authors declare no conflict of interest.  
A  
Tortuosity factor  
Bcf/m  
Billion cubic feet/meters  
Bgi  
Gas formation volume factor (rcf/scf)  
Bsm3  
Billion standard cubic meters  
ft  
Feef  
Higross  
Thickness (ft)  
MMsm3  
Millions standard cubic meters  
m  
Cementation exponent 1.7-3.0 (usually 2.0)  
n  
Saturation exponent 1.8-4.0 (usually 2.0)  
rcf/m3  
Reservoir cubic feet/meters  
Rt  
Formation resistivity (ohm/m)  
Rw  
Water resistivity at formation temperature (ohm/m)  
scf  
Standard cubic feet  
sm3/d  
Standard cubic meter/day  
Sw  
Water saturation (%)  
Swi  
Irreducible water saturation (%)  
Tcf/m  
Trillion cubic feet/meters  
\(\Delta\)t  
Transit time through formation (\(\mu\)s/ft)  
\(\Delta\)tf  
Transit time through fluid (\(\mu\)s/ft)  
\(\Delta\)tma  
Transit time through matrix, formation without fluid (\(\mu\)s/ft)