Page 221 - Gas Wettability of Reservoir Rock Surfaces with Porous Media

Application of Gas Wettability CHAPTER 6 205

slurry. Compared to other film-forming agents, and under the same condi-
tions, the effects of reducing API filter loss fromLCM-8 and HPHT filter loss
are obviously better than other film-forming materials. It illustrates that the
film-forming capability of amphiphilic polymer reservoir protecting agent
LCM-8 has stronger capacity for plugging.

6.1.4 Drilling Fluid Changes the Property of Rock Surface
and Offers Protection To Low-Permeability Reservoirs
To evaluate the effects of reservoir protecting agents FCS-08 and LCM-8,
33-531-4 upper polymer, inhibitive drilling fluid was selected as the basic
slurry, and a reservoir protecting drilling completion fluid of well slurry was
used. Various reservoir protecting materials at different concentrations were
added to the basic slurry and 14 sets of drilling completion fluid formulations
were designed (Table 6.6).

6.1.4.1 EVALUATION OF PLUGGING RATE
With artificial rock samples and LSY-1 core flow testing apparatus, pollution
assessment of various drilling completion fluids was conducted at 3.5 MP a

differential pressure at 80 C and with 12 hours pollution time, respectively.
The experimental data is shown in Fig. 6.8.
Compared to well slurry, when reservoir protection technology is adopted, the
permeability plugging rate shows obvious improvement, which means more
severe plugging is generated at the pollution end. At the same time, the degree
of plugging caused by the drilling fluid system of fluorine-containing

Table 6.6 Formulation of Drilling Completion Fluid

Number Drilling Fluid Formulation
Formulation I Upper stratum well slurry
Formulation II Formulation I 11%CMJ-2
Formulation III Formulation I 11% GPJ
Formulation IV Formulation I 10.3%FCS-08 1 1% LCM-8
Formulation V Formulation I ＋2% CMJ-2
Formulation VI Formulation I ＋2% GPJ
Formulation VII Formulation I 10.3%FCS-08 1 2% LCM-8
Formulation VIII Formulation I ＋2.5% CMJ-2
Formulation IX Formulation I ＋2.5% GPJ
Formulation X Formulation I 10.3%FCS-08 1 2.5% LCM-8
Formulation XI Formulation I 13% CMJ-2
Formulation XII Formulation I 13% GPJ
Formulation XIII Formulation I 10.3%FCS-08 1 3% LCM-8
Formulation XIV Formulation I 10.3%FCS-08 1 4% LCM-8

Broad-spectrum “oil film” temporary plugging agent GPJ was developed before by this project group,
which is the film-forming agent applied successfully in oil fields.
CMJ-2: The temporary plugging agent is universally used in China.