Investigating reservoir pressure transmission for three types of coalbed methane reservoirs in the Qinshui Basin in Shan’xi Province, China

Abstract

Based on the characteristics of seven representative coalbed reservoirs in the Qinshui Basin in Shan’xi Province, China, the reservoirs were classified as gas pressure reservoirs, water pressure reservoirs or hybrid pressure reservoirs. Reservoir modelling technology was adopted to study the 1000 day recoverability and reservoir pressure transmission process of three typical coalbed methane (CBM) wells, each of which represents one of the three coalbed reservoir classifications identified. The results indicate that the three reservoirs are quite different in terms of their drainage performance. For gas pressure reservoirs, reservoir pressure changes in a very small region around the well bore. The gas production of this type of reservoir is very low; hence, integrated coal and gas mining may be appropriate to enhance its recovery. Reservoir pressure propagates further in water pressure reservoirs but declines gradually. The gas recoverability in water pressure reservoirs is also low, which indicates that effective water drainage is the key technology for improving it. The pressure in hybrid pressure reservoirs propagates moderately in the whole effective region. This type of reservoir has the strongest gas recoverability and is suitable for CBM exploitation using surface to reservoir boreholes.

Engineering Properties Of Ceramsite Proppant And Its Application On Hydraulic Fracture For A Coalbed Methane Well

“…Active water is used widely and frequently in hydraulic fracture and has lots of advantages of little damage, low price, wide supplement and mature technology (Zou et al 2013). If some nitrogen is added into active water, the suspension property and proppant carrying capacity will be increased obviously, and a better fracturing performance will be obtained (Hou et al 2017;Ranjith et al 2018).…”

Gray Relational Analysis Optimization for Coalbed Methane Blocks in Complex Conditions Based on a Best Worst and Entropy Method

“…The reservoir permeability represents the development degree of pores and fractures in coal seam and influences the degree of the gas flow in effective pores of the coal seam [23,33]. Permeability not only regulates the output efficiency of CBM but also affects the radius of the drainage and depressurization funnel in the CBM well [34]. Theory and practice have confirmed that permeability is one of the important reservoir indices for controlling CBM output [35,36].…”

Modeling and prediction for gas production during coalbed methane drainage based on two indirect reservoir parameters

“…Because gas production is always undulate and relatively low in this stage, it is really hard to simulate. For this reason, simulators usually assume that there is no free gas in the reservoir (Wei and Zhang, 2010;Young, 1998;Zou et al, 2013aZou et al, , 2014. The assumption also exists in this study.…”

“…Effective desorption radius is the distance from well bore to the place where reservoir pressure starts to decline down to the critical desorption pressure, which is influenced by influence radius, as detailedly defined and explained in Zou et al (2013a) and Sun et al (2017bSun et al ( , 2018d. During CBM drainage processes, drainages of water and gas lead to the increases of influence radius and effective desorption radius, as described in Figure 1.…”

“…Thararoop et al (2012) amended Langmuir equations and developed a CBM modeling software, and used it to simulate the recovery performance of a well. Zou et al (2013aZou et al ( , 2013b used the COMET3 software to predict pressure transmission during CBM drainage for both single well and well net group, and adopted an improved model to accurately simulate pressure transmission and gas content decline (Zou et al, 2015). Ren et al (2017) developed a binary model for gas transport in both coal matrix and cleat, and simulated reductions of gas content during drainage processes under different conditions.…”