Page 262 - Gas Wettability of Reservoir Rock Surfaces with Porous Media

246 Gas Wettability of Reservoir Rock Surfaces with Porous Media

changed and other variables don’t change, the performance of the
degreaser can be evaluated. Taking the change of the addition amount
of the agents as an example, the experiment steps are as follows:
a. Mg oily cutting samples with P(%) oil content were prepared in
several samples, and were placed in centrifuge tubes, separately.
b. Degreased solutions were prepared at different concentrations and
separately placed in centrifuge tubes.
c. The centrifuge tubes were placed in the centrifuge machine, and the
parameters were set for centrifuging.
d. After the tubes were centrifuged, the waste liquor in centrifuge tubes
was poured into a waste liquor storage tank. The residue was poured
into glass vessels and air-dried.
e. Petroleum content P 1 (%) of the residues was measured, and experi-
mental oil degradation rate for every group was calculated P w (%).
The calculation formula for oil degradation rate P w (%) of oily
cuttings:

P 1
P w 5 1 2
P
wherein:
P w —Oil degradation rate of oily cuttings, %;
P 1 —Petroleum content in treated oily cuttings, %;
P—Petroleum content in untreated oily cuttings, %
Degradation Performance Evaluation of Degreaser
1. Measurement of oil content in oily cuttings
Field oily cuttings and sludge from certain wells in Xinjiang Oilfield
were prepared to measure the oil content. The results are shown in
Table 6.22. From the results, it can be seen that the oil content exceeds
the required value (less than 0.3%) set in the national standards
GB4284-84 Control Standards for Pollutants in Sludges from Agricultural
Use. If the oily cuttings are directly discharged into the surroundings,
they will pollute the environment, and hence safe disposal of the rock
cuttings and sludge should be processed.
2. Degradation performance evaluation of degreaser
Degreasing capability of the degradable degreaser was measured at
ascertain concentration, and the experimental procedure is:
a. 2.0 g oily cutting samples and 2.0 g oily sludge samples were
prepared and separately placed in two centrifuge tubes.

Table 6.22 Measurement Results of Oil Content of Oily Cuttings
Sample Source Oil Content (%)
Cuttings from a certain oil field in Xinjiang 14.4
Sludge from a certain oil field in Xinjiang 10.6