| Autor: |
Abhijit Gangopadhyay, Herb Sebastian, Coulibaly Aboubakar, Don Woodward, Atif M. Malayalam |
| Rok vydání: |
2013 |
| Předmět: |
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| Zdroj: |
Unconventional Resources Technology Conference, Denver, Colorado, 12-14 August 2013. |
| DOI: |
10.1190/urtec2013-004 |
| Popis: |
Multi-stage fracturing in horizontal wells in shale reservoirs creates a region of stimulated reservoir volume (SRV) around the subject horizontal well. Depending upon the stress state i n the reservoir the hydraulic fractures could be planar or form a network near the well. Furthermore, fractu re initiation may not take place at every perforation cluster and therefore every perforation cluster may not contrib ute to production. Wells initially deplete this region of stimulated reservoir rock and with time produce fr om reservoir beyond the SRV. We attempt to understand depletion in nano darcy reservoirs like the Haynesville Shale by u tilizing our state of the art reservoir simulation workflow, Top Down Reservoir Modeling (TDRM™)7 and present a case study on a ten stage Haynesville horizontal well. Following an in-depth analysis of the complet ion and acquired down hole microseismic data, a subsurface model was built and the SRV extent and equivalent hyd raulic fracture parameters were history matched using advanced genetic algorithms. Well production was forecasted to 40 years and this served as a means to calibrate our decline curves used in estimating our recovery. Histo ry matching two years of production indicated: 1) the fracture property estimates in the SRV region are independent of for mation permeability; 2) after around four years of production there is an onset of depletion beyond the SRV and ; 3) higher matrix permeability in the nonstimulated region led to higher recovery. Simulation indicates higher prod uction could be achieved with greater frac lengths (thereby bigger SRV), higher frac conductivities and better perm i n the SRV region. The extent of depletion observed in the reservoir provides valuable insights to spacing future w ells in this area. The simulation workflow and the lessons learnt through this study are being applied to our other Ha ynesville horizontals. Literature survey Decline curves have been accepted as a quick and efficient way of estimating r ecovery of shale and tight gas wells. The transient flow taking place in shale wells throughout well life an d the impact of adsorbed gas on production cannot be accounted for by decline curve analysis. Further there exists a need for a basis to support the bfactor (decline exponent) used in decline curve recovery estimation. At ea rly time, drastically different EURs (Estimated Ultimate Recovery) can be calculated due to uncertainty in the b values as shown in Fig 1. In Fig 1 the orange points represent sample production data and hyperbolic decline curves e xtrapolated from these points for b values from 1.2 to 1.6 are shown in the left logarithmic y axis. The corresponding cumulative gas curves for different b values are plotted in the right y Cartesian axis. A 1.7 Bcf range in 30 year EUR can be observed for b values from 1.2 to 1.6. Reservoir simulation could be used to model the transient flow and adsorbed gas in shale formations. It should, however, be noted that reservoir simulation does not provide a u nique solution but could provide a range of permeability and stimulated reservoir volume (SRV) estimates with reason able forecasts to support recovery estimation. The business purpose of this study was to address the risk of well performance falling below the reference type curve calculated by decline curve analysis . |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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