possibly (for transient analysis) you need the bulk modulus,
isothermal bulk modulus is the inverse of isothermal compressibility,
with many hydrocarbons the value of isothermail compressibility and bulk modulus have limited dependence from pressure,
for example for CH4 at 100K

p 1 Bar ->0.000198 1/Bar
p 10 Bar ->0.000194 1/Bar
p 50 Bar ->0.000175 1/Bar
p 100 Bar ->0.000157 1/Bar

values calculated with Prode Properties Soave Redlick Kwong Extended
as you see from 1 to 100 bar the difference is about 20% , I think you can assume the value as constant