- Industria: Oil & gas
- Number of terms: 8814
- Number of blossaries: 0
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The casing string that is usually put into the well first, particularly on land wells, to prevent the sides of the hole from caving into the wellbore. This casing, sometimes called drive pipe, is generally a short length and is sometimes driven into the ground. Conductor pipe is run because the shallow section of most wells onshore is drilled in unconsolidated sediment or soil rather than consolidated strata typically encountered deeper. Offshore, the drive pipe or structural casing may be installed prior to the conductor for similar reasons.
Industry:Oil & gas
The bottom of the casing string, including the cement around it, or the equipment run at the bottom of the casing string.
Industry:Oil & gas
The anion, SiO<sub>4</sub><sup>-4</sup>, found in solutions of sodium and potassium silicate, formed by dissolving silica or silicate minerals in NaOH or KOH solutions. Silicate anions form polysilicates, or colloidal silica gel.
Industry:Oil & gas
The amount of pressure (or force per unit area) in the wellbore that exceeds the pressure of fluids in the formation. This excess pressure is needed to prevent reservoir fluids (oil, gas, water) from entering the wellbore. However, excessive overbalance can dramatically slow the drilling process by effectively strengthening the near-wellbore rock and limiting removal of drilled cuttings under the bit. In addition, high overbalance pressures coupled with poor mud properties can cause differential sticking problems. Because reservoir pressures vary from one formation to another, while the mud is relatively constant density, overbalance varies from one zone to another.
Industry:Oil & gas
The amount of pressure (or force per unit area) exerted on a formation exposed in a wellbore below the internal fluid pressure of that formation. If sufficient porosity and permeability exist, formation fluids enter the wellbore. The drilling rate typically increases as an underbalanced condition is approached.
Industry:Oil & gas
The amount of oxygen consumed by biodegradation processes during a standardized test. The test usually involves degradation of organic matter in a discarded waste or an effluent.
Industry:Oil & gas
The amount of oxygen needed to oxidize reactive chemicals in a water system, typically determined by a standardized test procedure. COD is used to estimate the amount of a pollutant in an effluent. Compare to biochemical oxygen demand, BOD.
Industry:Oil & gas
The amount of mixing water specified in API Specification 10A for specification testing of cement to meet API requirements. This amount is not intended to be a guide for mix water requirements in field applications.
Industry:Oil & gas
The addition of a mud product to fresh water prior to adding it into the mud system. Bentonite clay and XC polymers are two additives whose performance improves by hydration in fresh water before adding them to a highly-treated or salty mud system.
Industry:Oil & gas
