Gas reservoirs with low permeability (k<0.1 mD) are among the unconventional reservoirs and are commonly termed as "Tight Gas Reservoirs". In conventional gas reservoirs that have high permeability, the flow of gas is basically controlled by the reservoir permeability and it is calculated using the Darcy equation. In these reservoirs, gas flow due to gas diffusion is ignored compared to Dar...

Building upon the foundation of the prior investigations, a three-fold classification of tight gas reservoirs is proposed in this paper which is based primarily on dynamic relationship between gas charging history and reservoir tightening process, coupled with tectonic evolution, source-reservoir relationship, migration and charging pattern. The three categories of tight gas are: (1) “pre-exist...

Although shale gas plays have been in the spotlight recently, natural gas in tight sandstones is actually also an important hydrocarbon resource. In many cases, tight gas sandstone resources can be developed more easily than shale gas reservoirs as the rocks generally have higher quartz content, and are more brittle and easier to complete for production. This chapter first gives an overview of ...

In this paper we analyze by means of numerical simulation the mechanisms and processes of flow in two types of fractured tight gas reservoirs: shale and tight-sand systems. The numerical model includes Darcy’s law as the basic equation of multiphase flow and accurately describes the thermophysical properties of the reservoir fluids, but also incorporates other options that cover the spectrum of...

Tight reservoir means reservoir of low porosity and low permeability. Many tight formations are extremely complex, produced from multiple layers with different permeability that is often enhanced by natural fracturing. The complicity of these reservoirs is attributed to a) Low porosity and low permeability reservoir, b) The presence of clay minerals like illite, kaolin and micas in pores, c) Th...

Unconventional gas resources from tight sand and shale gas reservoirs have received great attention in the past decade around the world, because of their large reserves as well as technical advances in developing these resources. As a result of improved horizontal drilling and hydraulic fracturing technologies, the progresses are being made towards commercial gas production from such reservoirs...

We discuss petrophysical analysis of wireline logs, methods for formation evaluation and issues in evaluating tight sandstone formations. The main concerns of log interpretation in tight gas sandstones include porosity interpretation, understanding the effect of clay on the log responses, accurate computation of water saturation, and permeability determination (Kukal et al., 1985). Moreover, va...

Unconventional gas resources from tight-sand and shale gas reservoirs have received great attention in the past decade around the world because of their large reserves and technical advances in developing these resources. As a result of improved horizontaldrilling and hydraulic-fracturing technologies, progress is being made toward commercial gas production from such reservoirs, as demonstrated...