Ultra-deepwater reservoirs are important unconventional reservoirs that hold the
potential to produce billions of barrels of hydrocarbons, but also present major
challenges. This type of reservoir is usually high pressure and high temperature (HPHT)
and has a relatively high permeability. Hydraulic fracturing high permeability reservoirs
are different from the hydraulic fracturing technology used in low permeability
formations. The main purpose of hydraulic fracturing in low permeability reservoirs is
to create a long, highly conductive path, whereas in high permeability formations
hydraulic fracturing is used predominantly to bypass near wellbore formation damage,
control sand production and reduce near wellbore pressure drop. Hydraulically
fracturing these types of wells requires short fractures packed with high proppant
concentrations. In addition, fracturing in high permeability reservoirs aims at achieving
enough fracture length to increase productivity, especially when the viscosity of the
reservoir fluid is high. In order to pump such a job and ensure long term productivity
from the fracture, understanding the behavior of the fracture fluid and proppant is
critical.
A series of laboratory experiments have been conducted to study conductivity
and fracture width with high proppant loading, high temperature and high pressure.
Proppant was manually placed in the fracture and fracture fluid was pumped through the
pack. Conductivity was measured by pumping oil to simulate reservoir conditions.
Proppant performance and fracture fluids, which carry the proppant into the fracture, and
their subsequent clean-up during production, were studied. High strength proppant is
ideal for deep fracture stimulations and in this study different proppant loadings at
different stresses were tested to see the impact of crushing and fracture width reduction
on fracture conductivity.
The preliminary test results indicated that oil at reservoir conditions improves
clean-up of fracture fluid left in the proppant pack compared with using water at ambient
temperature. Increasing the proppant concentration in the fracture showed higher
conductivity values in some cases even at high closure stress. The increase in effective
closure stress with high temperature resulted in a significant loss in conductivity.
Additionally, the fracture width decreased with time and increased effective closure
stress. Tests were also run to study the effect of cyclic loading which is expected to
further decrease conductivity.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2010-05-7957 |
| Date | 2010 May 1900 |
| Creators | Rivers, Matthew Charles |
| Contributors | Zhu, Ding |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | thesis, text |
| Format | application/pdf |
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