Doesn't your company have any past records? I would think that you could go to your company's old reports and lab test data and develop one for your use . . . it would be better than outside data by others because you could toss out the outliers or note which results might have been slightly off base. You might also wish to plot Logpressure vs logvoidratio to get a better handle on the past preconsolidation pressure. A little bit of homework on your end would be beneficial not only to you on this project but on future projects as well.