OILMUD: A Microcomputer Program for Predicting Oil-Based Mud Densities and Static Pressures
- E.J. Peters (U. of Texas) | M.E. Chevenver (U. of Texas) | A.M. Alhamadah (U. of Texas)
- Document ID
- Society of Petroleum Engineers
- SPE Drilling Engineering
- Publication Date
- March 1991
- Document Type
- Journal Paper
- 57 - 59
- 1991. Society of Petroleum Engineers
- 1.6 Drilling Operations, 1.11.2 Drilling Fluid Selection and Formulation (Chemistry, Properties), 2.7.1 Completion Fluids, 1.11 Drilling Fluids and Materials
- 0 in the last 30 days
- 281 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 5.00|
|SPE Non-Member Price:||USD 35.00|
OILMUD is a program for predicting the densities and hydrostatic pressures in oil-based mud columns at high pressures and temperatures. The program uses multiple-linear-regression analysis on experimental data to calculate the densities and static pressures for diesel-oil-based mud and for four less-toxic mineral-oil-based muds. This menu-driven, easy-to-use program runs on an EBM personal computer and compatible systems. It can be used by a drilling engineer to estimate downhole densities and pressures during drilling on the basis of surface measurements or to plan the mud program for a new well.
Oil-based muds are widely used to drill deep, hot wells. Because these muds compress with pressure and expand with temperature, their downhole densities can vary significantly from surface densities, depending on the pressure and temperature pro-files in the well. Therefore, to predict the hydrostatic pressures ex erted by oil-based muds accurately, the effects of pressure and temperature on the mud densities need to be considered. This fact has been recognized and studied previously. Until now, however, no convenient, easy-to-use method to incorporate the effects of pressure and temperature into the prediction of downhole pressures has existed. prediction of downhole pressures has existed. The objective of this study was to develop a computer program that could be used to predict downhole oil-based-mud densities and static pressures accurately at high pressures and temperatures. The program had pressures accurately at high pressures and temperatures. The program had to be easy to use and compatible with personal computers that are widely available to drilling engineers in the office and at the wellsite. This paper describes such a computer program and presents an example paper describes such a computer program and presents an example application.
OELMUD is based on the experimental data reported by Peters et al. In that paper, we demonstrated that the densities of oil-based muds at high pressures and temperatures can be predicted by a compositional material-balance model. We measured the density of base oils and calcium chloride solutions at high pressures and temperatures and then used these in the compositional material-balance model given in Eq. 1, to predict the densities of 11- and 17-lbm/gal oil-based muds.
The predicted and measured densities were in excellent agreement. Density measurements were made on diesel oil and four mineral oils from 78 to 350 degrees F and from 0 to 15,000 psig. The computer program uses multiple-linear-regression analysis to extend these experimental density data to a temperature of 450 degrees F and to pressures above 15,000 psig. The static pressure in the wellbore is calculated with the following nonlinear equations, (2)
Together with the surface conditions, (3) Given the temperature profile, the density from Eq. 1, and the surface pressure, Eq. 2 is integrated numerically to predict the static wellbore pressure, Eq. 2 is integrated numerically to predict the static wellbore pressure profile: pressure profile: (4)
|File Size||522 KB||Number of Pages||3|