Basic Theory of Chokes

Chokes will be divided into 4 main criterias, 1 types 2 reasons, 3 basic operations, and 4 application. there are few most common chokes used in the world of petroleum engineering, which is positive choke where the choke is have fixed orifice, and cannot change the bean size. and the second most common chokes is adjustable choke. the advantages of adjustable choe is provides variable orifice size through external adjusment

schematic of adjustable choke is a restrictions in a flowline that causes a pressure drop or reduces the rate of flow. it commonly uses partially blocked orifice or flow path. variable chokes is good for bringing wells on gradually and optimizing natural gas lift flow in some cases. prone to washouts from high velocity, particles, and droplets. the solution to fix this problems is hardened the choke using carbide components, chokes in series, or dual choke in well head

most comon positive choke/ bean choke is have id size 64 inch. there is a main function of chokes:
1. control flow to achieve liquid lift
2. maximize use - best use of gas
3. to protect equipment from abrasion and erosion
4. to make a cleanup -  best use of backflow energy
5. control circulation -  holds a back pressure
6. control pressures at surface during flow
7. control injection on injection line

Ideal Gas Mixtures

Table of Universal Gas Constant (R)

Gas Constant Table (R)

The Ideal Gas Equation of State

For n moles equation becomes

Density of an Ideal Gas

 Standard Conditions 

1.  Oil and gas occur under a whole range of temperatures and pressures
2. Convenient to express volumes at a reference condition. 
3.  Common practise to relate volumes to surface conditions. 14.7 psia and 60^oF 

Mixtures of Ideal Gases

       Petroleum gases are mixtures of gases - Dalton’s Law and Amagat’s Law 

 

   Dalton’s Law of Partial Pressures

             : Total pressure is the sum of the partial pressures