- Industry: Oil & gas
- Number of terms: 8814
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A formation encountered during drilling into which circulating fluids can be lost.
Industry:Oil & gas
A formal plan developed for a specific well with predictions and requirements at various intervals of the wellbore depth. The mud program gives details on mud type, composition, density, rheology, filtration and other property requirements and general and specific maintenance needs. Mud densities are especially important because they must fit with the casing design program and rock mechanics required in openhole to ensure wellbore pressures are properly controlled as the well is drilled deeper.
Industry:Oil & gas
A form of corrosion in which susceptible types of metals will break by a combination of stress within the metal and the specific type of corrosion. Sulfide corrosion of ferrous alloys and chloride corrosion of stainless steels are two common type of SCC. When high-strength steel remains in contact with hydrogen sulfide (or sulfide ion) in a water-mud environment, sulfide SCC may occur. Tool joints, hardened parts of blowout preventers and valve trim are particularly susceptible to brittle failure caused by sulfide SCC. For this reason, along with toxicity risks of hydrogen sulfide gas, it is essential that water muds be kept entirely free of soluble sulfides and especially hydrogen sulfide at low pH.
Industry:Oil & gas
A fluid-loss control additive used in high-temperature, water-base muds. It shows good salt tolerance and temperature tolerance.
Industry:Oil & gas
A fluid with water or brine as droplets dispersed into an external phase of oil.
Industry:Oil & gas
A fluid whose viscosity is not constant at all shear rates and does not behave like a Newtonian fluid. Most successful drilling fluids are non-Newtonian. Within that group are several general types and rheological mathematical models to describe them. Pseudoplastic is a general type of shear-thinning, non-Newtonian behavior that is desirable for drilling fluids. Bingham plastic and power-law models describe a psuedoplastic behavior using only two measurements (two parameters). The Herschel-Bulkley model is a three-parameter rheological model.
Industry:Oil & gas
A fluid that has a constant viscosity at all shear rates at a constant temperature and pressure, and can be described by a one-parameter rheological model. An equation describing a Newtonian fluid is given below. <br><center><img src="files/OGL99113. Gif" alt="Newtonian fluid" border="0" vspace="8" /></center><br>Water, sugar solutions, glycerin, silicone oils, light-hydrocarbon oils, air and other gases are Newtonian fluids. Most drilling fluids are non-Newtonian.
Industry:Oil & gas
A fluid in which the shear force is not proportional to the shear rate (non-Newtonian) and that requires a finite shear stress to start and maintain flow. Most drilling muds are characterized as either plastic or pseudoplastic fluids.
Industry:Oil & gas
A fluid described by the two-parameter rheological model of a pseudoplastic fluid, or a fluid whose viscosity decreases as shear rate increases. Water-base polymer muds, especially those made with XC polymer, fit the power-law mathematical equation better than the Bingham plastic or any other two-parameter model. Power-law fluids can be described mathematically as follows: <br><center><img src="files/OGL99114. Gif" alt="Power-law fluid" border="0" vspace="8" /></center>
Industry:Oil & gas
A compound of sulfur that contains the S<sup>-2</sup> ion. H<sub>2</sub>S is the gaseous and highly toxic molecular form often found in the subsurface. Sulfide, S<sup>-2</sup>, and bisulfide, HS<sup>-</sup>, are the corresponding ionic forms. Sulfides can be generated from soluble iron sulfide minerals or from sulfate-reducing bacteria. The term "active sulfide" is used to denote compounds that revert to H<sub>2</sub>S gas when acidified with 2-molar citric acid solution, as opposed to inert sulfides, which are stable. Active sulfides include calcium sulfide and bisulfide formed when H<sub>2</sub>S reacts with lime in an oil mud. Their accumulation constitutes a safety concern at the rig because of the risk of reverting to H<sub>2</sub>S gas should an acidic influx occur. They may be converted to inert sulfides by adding zinc oxide. <br><br>Reference:<br>Garrett RL, Carlton LA and Denekas MO: "Methods for Field Monitoring of Oil-Based Drilling Fluids for Hydrogen Sulfide and Water Intrusions," SPE Drilling Engineering 3, no. 3 (September 1988): 296-302.
Industry:Oil & gas
