Hydraulic Fracturing Practices for Sustainable Production in Gas Wells: Approach, Methodology, Results, and Comparison with Offset Gas Wells Case Histories

Abstract

Nowadays tight oil and gas reservoirs all around the world are increasingly exploited using wells where hydraulic fracturing is an essential technique to enable commercial productivity. In the case of a low permeability sandstone gas reservoir, understanding geological environment and selection of the optimal hydraulic fracturing design and implementation is key to obtain sustainable flow rates. Analysis of performed frac jobs and well performance across one field with 6 gas offset wells is reviewed in this paper. Wells analyzed in this paper were all drilled into a shaly sandstone reservoir, with a high probability of including a favorable net-to-gross ratio of reservoir quality sandstones. The reservoir properties of these sandstone formations vary from a well to another with an average reservoir pressure of 5,500 psi – 8,500 psi, average reservoir temperature of 300 deg F, average reservoir porosity of 6-10% and average permeability between 0.5 – 4 mD. These reservoir properties are indication of tight reservoir where hydraulic fracturing is an essential technique to enable commercial productivity from the wells as well as controlling proppant and sands flowback. In most cases, 20/40 HSP and 20/40 RC-HSP proppant types were used in frac operations to provide the required conductivity in the reservoir and also control the proppant and sand from being flowed back to the surface. In addition to the proppant type, high final proppant concentration was also one of the key parameters to ensure proppant packing is achieved at the end of the job and help minimizing proppant flow back. High level analysis of the wells production histories across the field will help to determine main factors affecting the well performance.