- Settore: Oil & gas
- Number of terms: 8814
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A type of water-base mud that is saturated with lime, Ca(OH)<sub>2</sub>, and has excess, undissolved lime solids maintained in reserve. Lime muds are classified according to excess lime content: (1) low-lime, 0. 5 to 2 lbm/bbl, (2) medium-lime, 2 to 4 lbm/bbl and (3) high-lime, over 4 lbm/bbl. All lime muds have pH in the range of 12, and the filtrate is saturated with lime. Fluid-loss additives include starch, HP-starch, carboxymethylcellulose (CMC) or polyanionic cellulose (PAC). Prehydrated bentonite can improve the fluid loss and rheology of a lime mud. A maltodextrin in lime muds has been used as a clay deflocculant, a shale stabilizer and to increase calcium solubility. KCl in lime muds has been another innovation for successful drilling of hydratable shales. The ability to carry very high mud alkalinity (as excess lime) to neutralize acid gases is one reason lime muds are used. H<sub>2</sub>S zones can be drilled with more safety and copious amounts of CO<sub>2</sub> can be neutralized by a large excess of lime.
Industry:Oil & gas
A type of viscometer generally used in laboratories to test drilling fluids at simulated downhole conditions.
Industry:Oil & gas
A type of static filtration test for water-base drilling fluid that measures the filtration rate (time for free water to pass between two electrodes) using filter paper as the medium. It is used primarily to indicate filter-cake permeability, but data from the test have been used to study how clays and shales react in filter cakes and how brines of various types affect clays in a filter cake.
Industry:Oil & gas
A type of shale-inhibitive water mud that contains sodium or potassium silicate as the inhibitive component. High pH is a necessary characteristic of silicate muds to control the amount and type of polysilicates that are formed. Mud pH is controlled by addition of NaOH (or KOH) and the appropriate silicate solution. Silicate anions and colloidal silica gel combine to stabilize the wellbore by sealing microfractures, forming a silica layer on shales and possibly acting as an osmotic membrane, which can produce in-gauge holes through troublesome shale sections that otherwise might require an oil mud. Mud containing up to 50 vol. % soluble sodium silicate was first used in the 1930s for control of shale but suffered from gelation problems. In the 1990s, silicate muds were reintroduced as a way to avoid using oil muds. The newer systems use lower silicate concentrations and KCl or NaCl or both to contribute to shale control. This comeback may succeed due to better solids control and proper use of silicate chemistry. Poor lubricity and temperature tolerance are the main drawbacks.
Industry:Oil & gas
A type of sealing element in high-pressure split seal blowout preventers that is manufactured with a half-circle hole on the edge (to mate with another horizontally opposed pipe ram) sized to fit around drillpipe. Most pipe rams fit only one size or a small range of drillpipe sizes and do not close properly around drillpipe tool joints or drill collars. A relatively new style is the variable bore ram, which is designed and manufactured to properly seal on a wider range of pipe sizes.
Industry:Oil & gas
A type of organic compound of carbon and hydrogen that contains one or more saturated cyclic (ring) structures, or contains such structures as a major portion of the molecule. The general formula is C<sub>n</sub>H<sub>2n</sub>. Naphthenic compounds are sometimes called naphthenes, cycloparaffins or hydrogenated benzenes. Naphtha is a refined petroleum fraction that contains a high percentage of these types of hydrocarbons. In drilling fluids, particularly oil-base muds, the amounts and types of hydrocarbons in the mud can be an important parameter in the overall performance of the mud.
Industry:Oil & gas
A type of pipe wrench used for hand-tightening various threaded connections around the rigsite. It consists of a handle, a set of gripping die teeth, a length of flat chain and a hooking slot where the chain may be adjusted to fit the pipe.
Industry:Oil & gas
A type of salt in which chromium atoms are in the plus-7 valence state, such as potassium dichromate, K<sub>2</sub>Cr<sub>2</sub>O<sub>7</sub>.
Industry:Oil & gas
A type of salt in which chromium atoms are in the plus-6 valence state, such as potassium chromate, K<sub>2</sub>CrO<sub>4</sub>. Chromium compounds of various types have been used in lignite and lignosulfonate and other mud additives to enhance thermal stability. Since the late 1970s, they are prohibited in muds to be discarded offshore and in other environmentally sensitive areas of the US.
Industry:Oil & gas
