| Abstract | Unconventional energy resources have been characterized as those with large
scale geometry and reserve, poor reservoir quality, which are difficult to evaluate and
to apply the traditional techniques to develop for economic production.
Unconventional oil and gas migration and flow mechanism dominate its exploration
and development mode, which potentials are largely formation controlled. Very often,
formation stimulation in unlocking the reservoir potential, such as fracturing
technique is the key to develop unconventional reservoirs, such as the shale oil and
gas, as well as the tight gas reservoirs. The state-of-art technology for tight oil and gas
development is through long horizontal well with multi-stage fracturing.
Presented in this study, based on the thorough study of unconventional reservoirs
matrix and fracture seepage mechanism, and considering the finite conductivity and
infinite conductivity fractures; as well as the parameters such as fracturing completely
penetrating or partially penetrating; perforation in the fractures and between fractures,
fracture half length, fracture dipping, fracture spacing etc., the multi-stage fracturing
horizontal well test interpretation models are established. The model takes into
account broader factors and wide field application conditions, therefore, more robust
than other published fractured horizontal well test models. The current model for well test interpretation was solved using modern mathematical
analysis methods. The type curves of multistage fracturing horizontal wells were
generated. These type curves reflect the reservoir dynamic responses including those
due to the main flow stage; the seepage flow characteristics of each stage, as well as
the number of fractures, fracture half length, fracture conductivity, fracture inclination
angle and other response characteristics. These type curves were then used by type
curve matching methods to the well testing data from a field case, to calculate the
reservoir and fracture parameters.
The field application and case study have shown that the developed well testing
model can meet the actual production evaluation requirements, and the results are in
good agreement with those published for unconventional tight oil and gas reservoir
evaluation.
Keywords: unconventional, multi-stage fracturing, horizontal well, interpretation
model, well test interpretation |
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