Drilling-fluid densities vary significantly over wide ranges of temperature and pressure, a concern that is particularly critical in deepwater, Arctic, and high-pressure/high-temperature. The variations can affect well integrity, well design, regulatory compliance, and drilling efficiency.Drilling-fluid densities depend on the compressibility and thermal expansion of the fluids (liquids) and solids used in their formulation. Suitable pressure/volume/temperature (PVT) correlations for these fluids previously have been fairly inaccessible, primarily because of continually changing base fluids and blends, and the lack of readily available test equipment.This study was conducted to measure the volumetric behavior under extreme temperatures and pressures of a broad range of the oils, synthetics, and brines currently used in industry to prepare oil-, synthetic-, and water-based drilling fluids. It follows a recent study that successfully qualified the commercially available test equipment.For the most part, tests for this study were run at temperatures from 36 to 600 F and pressures from atmospheric to 30,000 psi, ranges that generally exceed those provided in other published studies. Correlation coefficients are provided for reference and to demonstrate their use in a compositional, material-balance model to accurately predict drilling-fluid density as a function of temperature and pressure. Tests run on field drilling fluids are included to demonstrate how these data can be used in procedures and software to predict equivalent static density and hydrostatic pressure during drilling operations.

Drilling fluid densities vary significantly over wide ranges of temperature and pressure, a concern that is particularly critical in deepwater, Arctic, and high-temperature/high-pressure wells. The variations can impact well integrity, well design, regulatory compliance, and drilling efficiency. Drilling fluid densities depend on the compressibility and thermal expansion of the fluids (liquids) and solids used in their formulation. Suitable pressure-volume-temperature correlations for these fluids previously have been fairly inaccessible, due primarily to continually changing base fluids and blends, and the lack of readily available test equipment. This study was conducted to measure the volumetric behavior under extreme temperatures and pressures of a broad range of the oils, synthetics, and brines currently used in industry to prepare oil, synthetic, and water-based drilling fluids. It follows a recent study that successfully qualified the commercially available test equipment. For the most part, tests were run at temperatures from 36 to 600°F and pressures from atmospheric to 30,000 psi, ranges that generally exceed those used in published studies. Correlation coefficients are provided for reference and to demonstrate their use in a compositional, material-balance model to accurately predict drilling fluid density as a function of temperature and pressure. Tests run on field drilling fluids are included to demonstrate how these data can be used in procedures and software to predict equivalent static densities and hydrostatic pressure during drilling operations.

Highly deviated or horizontal wells have led to new thinking in the application of well completion and stimulation technology. Horizontal drilling technology has advanced rapidly over the past few yews. It is now common to be able to drill and control horizontal holes of greater than 1,000 ft. displacement. However, horizontal completion technology is still on a steep learning curve and many completion practices need to be refined to contribute to the economic success of a horizontal project. In addition, a better understanding of reservoir performance with horizontal completions will be needed. Proven completion techniques used in less deviated wells have not proved to be cost effective or, efficient in this new application. This paper addresses several of these problem areas by discussing the shortcomings of vertical well completion technology and offers solutions to horizontal applications. Specific completion areas discussed include production string isolation, influence of horizontal wellbore deviation, stimulation considerations, sand control and downhole production equipment. Case histories of three Bima Field wells, offshore Indonesia, are presented to illustrate various completion practices. Introduction Since the usual purpose to drill and complete horizontal wells is to enhance production, the completion program must match the production objectives. There are many circumstances which lead to the decision to drill horizontal wells and these must also be considered in the final completion design. These circumstances, almost all reservoir related, include : - Thin Reservoirs. The Productivity Index (PI) for a horizontal well reflects the increased area of contact of the well with the reservoir. Typically the PI for a horizontal well may be increased by a factor of 4 compared to a vertical well penetrating the same reservoir, although enhancement by a factor of 10 or more may be achievable in certain circumstances (Fig.1). - Vertical Permeability. The productivity obtained by drilling a horizontal well partially depends on the magnitude of the vertical permeability and the length of the drainhole. P. 335^

Density profiles of brines and other well fluids are critical to determining true downhole static pressures during completion, workover, and testing operations. Low-temperature conditions in deepwater applications and elevated temperatures and pressures in high-temperature/high-pressure (HTHP) wells, in particular, can distort predictions if pressure-volume-temperature (PVT) characteristics are not properly considered. The simple, yet useful, PVT method widely used in the industry for heavy completion brines typically works well; however, non-linear behavior diminishes accuracy for lower-salinity brines. In addition, the current industry database is relatively small and does not cover the glycol blended fluids used for thermodynamic hydrate protection in deepwater wells. Presented in this paper are new PVT measurements made on a range of selected completion brines with nominal densities from 8.345 to 14.4 lbm/gal. Also included is an improved model that addresses non-linear behavior and permits more accurate determination of density profiles under downhole conditions. Test fluids include deionized water, seawater, calcium chloride, sodium chloride, calcium bromide, ethylene glycol, propylene glycol, and fresh-water/glycol mixtures. Tests were conducted using a commercial HTHP pycnometer at pressures to 30,000 psig and temperatures from 35°F to 500°F. Regression analyses generated a polynomial equation that provides excellent fits over the wide range of fluids and test conditions, including those exhibiting non-linearity. The complete list of correlation coefficients for the test fluids is included. The new model also is suitable for base oils and synthetics.