Page 265 - Gas Wettability of Reservoir Rock Surfaces with Porous Media

Application of Gas Wettability CHAPTER 6 249

Table 6.26 Analysis of Pollutants Before and After Treatment
Oil Content Hg/mg/kg Cd/mg/kg
(%)
Before treatment 12.02 5.56 6.91
After treatment 0.66 0.01 0.02
Emission Primary Primary, Primary,
concentration limit of standard # 1% secondary, and secondary, and
pollutant during tertiary tertiary
GB4914-2008 offshore standards # 1 mg/L standards # 3 mg/L
oil exploration and
developmentEmission
concentration limit of
nonwater-based
drilling fluids

6.4.3 Field Applications
Taking the field application in Tarim Oilfield as an example, which lies in the
Taklamakan Desert within Xinjiang Uygur Autonomous Region, it boasts of
rich petroleum and natural gas reserves. During exploration, oil-based drilling
fluid was frequently used to protect oil and gas reservoirs. How to deal with
the oily cuttings generated during this process of oil-based drilling fluid is one
of the main environmental problems existing in the field. This text proposes
the oily cutting treatment technology through component analysis and
pollution feature analysis of field oily cuttings. It has also been applied to
Yihe 2AH and Sangta 2 10 wells, with good environmental, economic, and
social benefits.

6.4.3.1 GENERAL INFORMATION ON THE TEST WELLS
Yihe 2AH well is an old, horizontal, side-drilling exploration well. To main-
tain the well walls’ stability and protect reservoirs, diesel oil with an oil-water
ratio of 9:1 was adopted in the well section 5500B6710 m, as the oil-based
drilling fluid.
The formation rocks of Sangta 2 10 well include a lot of mudstone, silt mud-
stone, creamy mudstone, and coal beds. They exist in unstable positions, and
diesel oil was used in well section 800B4670 m as the oil-base drilling fluid.

6.4.3.2 FIELD CONSTRUCTION PROCESS FOR TREATMENT OF
OILY CUTTING
According to the experimental analysis data and actual field status, a harm-
less “resource recycling and integrative treatment process” was proposed,
including degreasing through chemical cleaning of oily cuttings and oily