An Evaluation of Microseismic Monitoring of Lenticular Tight Sandstone Stimulations

Abstract

Microseismic monitoring in lenticular tight gas formations has a number of challenging issues associated with both analysis and interpretation. The heterogeneous nature of the reservoir and the typically small microseismic-event amplitudes make it essential to understand the limits of interpretation that should be applied in these reservoirs. With proper care, fracture lengths and azimuth, along with zonal coverage, are readily obtainable. However, fracture-height growth in these complex reservoirs needs to be carefully assessed. Microseismic data provides a level of self-QC potential through the use of a magnitude-distance assessment to guide interpretation and design. Hydraulic fractures observed in these reservoirs tend to be long penetrating fractures that wander through the distributed-sand lenses, with modest height growth in most projects.

Underground microseismic monitoring of a hydraulic fracturing operation for CBM reservoirs in a coal mine

“…10 It was found that HF fractures usually passed through rather than simply along the formation. 11 And the MS activities mainly occurred in the direction perpendicular to the minimum principal stress and were partially influenced by the faults. 12 MS monitoring technique is also used for HF evaluation in geothermal development.…”

An XFEM Model for Hydraulic Fracturing in Partially Saturated Rocks

“…The hydraulic loadings can be either positive for pressurised fluid within the fracture or negative due to suction in the lag region. Therefore, the natural boundary conditions for loading at the fracture discontinuity is expressed as dσ.n c =dt-dp f n c (2) where σ is the total stress, t is the cohesive tractions, p f is the average fluid pressure within the fracture, and n c is the outward unit vector normal to the discontinuity ( Figure 1). Notice that in the above equation Biot's coefficient is not applied to fracture loading, and that the fluid pressure in the fracture is treated identical to an external pressure applied to fracture planes.…”

“…Typical examples are: fractured oil reservoirs [1], hydraulic fracturing for enhanced hydrocarbon production, tight gas reservoirs [2], weakly consolidated offshore sediments [3], soft coal bed methane extraction [4], geothermal energy [5,6], isolation of hazardous waste [7], measurement of in situ stresses [8], fault reactivation [9], and remediation of soil and ground water aquifers [10] to name a few.…”