Info Mdd
normally pressured formations, which have a self-supporting structure of solid particles so the pore pressure depends only on the weight of the overlying pore fluids , and abnormally pressured or geopressured formations, which are not fully compacted into a self-supporting structure so the pore fluids must bear the weight of some or all of the overlying sediments as well as the weight of the overlying fluids . The hydrostatic pressure gradient of formation fluids varies from 0.43 psi ft to over...
Drilling Fluid Selection
Over the years a considerable number of drilling fluid formulations have been developed to suit various subsurface conditions. Selection of the best fluid to meet anticipated conditions will minimize well costs and reduce the risk of catastrophes such as stuck drill pipe, loss of circulation, and gas kicks. Consideration must also be given to obtaining adequate formation evaluation and maximum productivity. The different types of drilling fluids that are available have been summed up by...
Mud Handling Equipment
Drilling equipment capability may affect the drilling fluids program. Inadequacies in pumps, mixing equipment, or solids-removal facilities will be likely to increase consumption of materials, and sometimes the preferred program must be modified to compensate for deficiencies in the equipment. The importance of the drilling equipment to the success of the mud program deserves a more extensive treatment than can be given here. Hutchison and Anderson summarize in tabular form Table 1-4 the...
Rapid Growth of the Mud Industry
After the California Division of Oil and Gas Operations was established in 1915, the employment of engineers in the oil industry began to increase. Usually, the engineers were concerned only with production and little attention was given to drilling.20 Several discussions on the use of mud were reported, however, in Summary of Operations California Oi Fields2 J and some of these were reprinted in oil industry publications.22 The mechanism of wall building in the drill hole was studied to some...
Waterbase Drilling Fluids Technology
If drilling fluid is defined as a material employed to aid tools in the creation of a borehole, the use of drilling fluids far antedates the petroleum industry. Water, the principal constituent of the majority of drilling fluids in use today, was the first drilling fluid. As early as the third millenium in Egypt, holes up to twenty feet deep were drilled in quarries by hand-driven rotary bits. J.E. Brantly, the recognized authority on the history of drilling, concludes that water probably was...
Pressure Control by Mud Density
A serious problem the enormous waste of natural gas in drilling by the cable-tool method in Oklahoma led to the general acceptance of mud laden fluid as a means of controlling pressure. In May 1913, Pollard and Heggem11 11 of the U.S. Bureau of Mines, demonstrated the practicality of Figure 2-3. This mud mixer used shortly after the turn of the century served the same purpose as today's mixers. From Gray,89 World Oil. Figure 2-3. This mud mixer used shortly after the turn of the century served...
Info Ujr
Solids Content of Drilling Mud Volume Percent Figure 2-9. Effect of solids on drilling performance. From World Oil. Further studies96 led to the introduction of a bentonite extender polymer for the preparation of a low-solids, fresh-water mud. This mud was composed of about 3 by weight of bentonite, 0.01 polymer and 0.05 soda ash. A five-well test program in Wood County, Texas, showed the effect of solids content on drilling progress, as illustrated in Figure 2-9.9 7 In a later report,98 the...
Salt Water Muds
Early field experience, as well as laboratory studies, established that bentonite was the most practical material for improving the viscosity and wall-building properties of fresh-water muds. As dissolved salt content increased, however, bentonite became progressively less effective. In saturated salt water, bentonite did not swell, and contributed little toward reduction of filtration. To thicken salty muds, bentonite was mixed into fresh water and the resulting thick slurry was added to the...
Hole Stabilization Wall Building
An application for a U.S. patent, filed in 1887 by M.J. Chapman, proposed a stream of water and a quantity of plastic material, whereby the core formed in the casing will be washed out and an impervious wall be formed along the outside. He suggested clay, bran, grain, and cement. Here was another function of the drilling fluid to plaster the wall of the hole and reduce caving tendencies. Figure 2-2. Sweeny's rotary drill of 1866 had some features in common with rigs of today. Courtesy of NL...
HighpH Muds
In the 1930s the most popular thinning agent for muds was quebracho extract. This vegetable tannin, derived from a South American hardwood tree, has a deep red color when dissolved with caustic soda. High concentrations of caustic-quebracho produced high-pH mud which had some desirable features in shale drilling in particular, low gel strength and great tolerance for shale solids. 5 5 From the high-pH red mud came the red lime mud, or lime mud, that was consistently the most popular mud in the...
Oilbase Drilling Fluids Technology
Oil-base drilling fluids have been developed to overcome certain undesirable characteristics of water-base muds. These deficiencies are primarily due to the properties of water specifically, its abilities to dissolve salts to interfere with the flow of oil and gas through porous rocks to promote the disintegration and dispersion of clays and to effect corrosion of iron. In addition to providing a means for avoiding these objectionable features of water muds, oil muds offer potential advantages...
Solids Removal Equipment
The importance of removing drilled solids has been emphasized several times in the preceding sections. The advantages of doing so may be summarized as 1. Less barite and mud additives required. 2. Better rheological properties because the reduction in plastic viscosity increases the YP PV ratio, thereby promoting shear thinning. 3. Lower plastic viscosity facilitates the removal of entrained gas, hence lower mud densities can safely be carried. 4. Faster drilling rates, because of lower...
Oil Emulsion Muds
At about the time that lime muds came into use in Gulf Coast drilling, oil emulsion mud was recognized as a method of making a good mud better. Much earlier, oil had been used to loosen stuck drill pipe and to slick up the hole before running casing25. Drillers in the Oklahoma City field 1934 -1936 added crude oil to mud to reduce sticking of pipe, and in 1937 a drilling contractor in Pottawatamie County, Oklahoma, noted a faster drilling rate after adding oil.66 By 1950 numerous reports of...
Birth of the Mud Industry
The use of barite in oil well drilling attracted the interest of Phillip E. Harth, sales manager for National Pigments and Chemical Company, a subsidiary of National Lead Company and a producer of barite for the pain t industry. Mr. Stroud16 accepted Mr. Harth s offer of assistance in securing a patent on the addition of heavy minerals to mud in return for exclusive sales rights under any such patents. Paint-grade barite from the St. Louis, Mo. plant was sold for oil well use under the brand...