Concepts.for.GATE

Joule - Thomson Effect . ... The  Joule - Thomson  (JT)  effect  is a thermodynamic process that occurs when a fluid expands from high pressure to low pressure at constant enthalpy (an isenthalpic process) .   The cooling occurs because work must be done to overcome the long-range attraction between the gas molecules as they move farther apart. The frequency of atomic collisions decrease as air  expands , therefore the air gets cooler . Temperature is just the average heat of a substance. As the energy needed to increase it's temperature must be supplied from somewhere, and the  gas  does not takes the energy from the surrounding system giving the effect of cooling. Most of the real gases need more work downstream at ambient temperature, due to the effects of compressibility. P   1  × V  1  < P   2  × V   2 The indicates that the internal energy decreases when the gas passes through the restriction . It ca...

Exploration wells are tentative ventures that drill in new areas with the hope of discovering untouched resources.  These tend to be the highest risk wells in terms of failure versus success. Exploratory Well (Succeed) Appraisal wells are used to evaluate the characteristics of existing hydrocarbon accumulation. An oil and gas company will typically go on to drill an appraisal well once a discovery has been made. The wells, which have a higher chance of success and are more expensive than exploration wells, are used to determine the size of an oil gas field (both physically and in terms of its reserves) and its expected production rate.  Appraisal wells can offer the best risk/reward ratios when speculating on drill outcomes.  Appraisal wells Wildcat wells are projects located outside of already established oil and gas fields. Wildcat wells are usually drilled to find out if there is any oil or gas present in an unproven location. However, they can also be used to extend ...

This is not a conventional Sucker Rod Pumping unit. This is special type of Pumping unit which is, Air balanced SRP. The air-balanced unit is a * rear mounted, class III lever system with Air Counter balance machine first built by Lufkin in early 1950’s.   (*Gear reducer and all accessories will be mounted at rear side of SRP). This machine uses the pitman to both push the walking beam up and pull the beam down to make a pumping cycle. The air-balanced unit uses an air tank fitted with an opened ended cylinder and piston to counterbalance the pumping unit. On the down stroke, air in the tank is further compressed thus storing energy in the compressed air.  Then on the up stroke the stored air energy is used to help lift part of the rod and fluid load. The piston uses piston rings to seal a pool of oil on top of the piston.  The pool of oil, in turn, seals the air from escaping from the tank and lubricates the piston/cylinder interface.    Click on icons ...

Petroleum Exploration:  Classification and description of some common rocks with special reference to clastic and nonclastic reservoir rocks.  Origin, migration and accumulation of Petroleum.  Petroleum exploration methods.  Oil and Gas Well Drilling Technology:  Well planning.  Drilling method.  Drilling rigs Rig operating systems.  Drilling fluids function and properties.  Drilling fluid maintenance equipment.  Oil & gas well cementing operations.  Drill bit types and their applications.  Drill string & Casing string  function,  operations,  selection & design.  Drilling problems, their control & remedies.  Directional drilling tools.  Directional survey.  Application of horizontal, multilateral, extended reach, slim wells.  Reservoir Engineering:  Petrophysical properties of reservoir rocks.  Coring and core analysis.  Reservoir fluid properties.  Ph...

Verbal Ability:   English grammar,  sentence completion,  verbal analogies,  word groups,  instructions,  critical reasoning and  verbal deduction.  Numerical Ability:   Numerical computation,  numerical estimation,  numerical reasoning and data interpretation    Click on icons to follow Us.

Mathematics Petroleum Engineering GATE syllabus Linear Algebra:  Matrix algebra,  Systems of linear equations,  Eigen values and eigenvectors.  Calculus:  Functions of single variable,  Limit, continuity and differentiability,  Taylor series,  Mean value theorems,  Evaluation of definite and improper integrals,  Partial derivatives,  Total derivative,  Maxima and minima,  Gradient, Divergence and Curl,  Vector identities,  Directional derivatives,  Line, Surface and Volume integrals,  Stokes, Gauss and Green’stheorems.  Differential equations:  First order equations (linear and nonlinear),  Higher order linear differential equations with constant coefficients,  Cauchy’s and Euler’s equations,  Initial and boundary value problems,  Laplace transforms,  Solutions of one dimensional heat and wave equations and Laplace equation.  Complex variables:  Complex numbe...

At infinite average or mean pressure, gas molecules will be as closer as liquid, So gases will behave like liquids at higher mean pressure. So, high mean pressure means less inverse of mean pressure (1/Pm). So, at zero inverse pressure, there should be minimum absolute permeability.amd that's callled liquid permeability. So, according to klinkenberg, it follows straight line rule and we can express it like, Gas permeability = liquid permeability *(1 + (b/Pm)) Pm is mean pressure. So, at infinity mean pressure, (zero inverse mean pressure), Gas permeability is equal to liquid permeability. Now, in lab, we can not go for infinitiy pressue (zero inverse pressure),so we obtain data which are possible (shown in continuous line in graph) and as we know it is straight line, we extrapolate it to zero inverse of mean pressure. (Intercept of line). And get liquid or Absolute  Permeability of that rock. For low molecular weight gases, it will be easier to slip through pores that's why the...

Imagine, you are a Petroleum reservoir and you are giving oil to the several oil wells. You are giving oil to all wells with lot of energy. After some time, you might be feel like, your energy is draining. Your energy is reducing with reducing fluid content from yourself. Like you are depleting along with your energy (pressure of reservoir is depleting.) So, earlier you were delivering fluid to the surface, but as of now, you do not have sufficient energy to lift it to the surface of well. So, you will deliver fluid to the level at which your energy permits. Right ? Suppose, we have well of 10000 ft depth, and you can now only lift your fluid to only 5000 ft only. So,  How this fluid will cover remaining 5000 ft of distance ? Any idea ? (Hint for you, it will be helpful if some one else can do your help, to lift that fluid from you.) And that lifting help is called Artificial lift. Now think, how can we lift fluid from bottom to surface ? Easiest way we can visualise is, if we have...

1)  Formation damage. I concluded all things, which i merged during my GATE preparation in this link in easy language. ( Formation damage. ) 2)  Well stimulation techniques.   Basics of well stimulations. Mainly two techniques, Hydraulic Fracturing and Acidization. Hydraulic fracturing: Basics Process  Proppants Additives of fluid Mini frac test Leak off test Acidization: Matrix acidization : Basics  , Acid used, Acid additives. Acid fracturing, Difference between all 3 types of acid jobs. Selection Criteria for Well stimulaton , Difference between workover and well stimulation. Numericals:  Acid volume required during Matrix Acidization.  Rock stress strain relations, poision ratio.(No correlations).      2) Artificial lift techniques.  This is vast topic which includes Sucker rod pumping, Gas lift, Electrical submersible pumping, Hydraulic pump, plunger lift etc. You will have PPTs from college. Start from there. I entirely d...

Here is straight forward points, which discriminate Pump, Compressors and Turbine. Turbine : It Withdraws Energy from Fluids. Fluid energy is converted into mechanical energy, and then to electrical energy. Pumps: Used for Liquids (Incompressible Fluids) Generally. It imparts Energy to Fluids. Increase the kinetic energy of the fluid which further increases the pressure energy . While transferring or sending or moving the fluid the volume remains constant from inlet or outlet. pumps are designed to develop relatively little pressure against a free-flowing system with minimal backpressure. Cheaper than Compressors. No storage of fluids before and after pumping. Compressors: Used generally for Gases (Compressible Fluids). Can not be used for Liquids (Liquids has very less Compressibility) It imparts Energy to Fluids. Increase the potential energy by pressuring gases in smaller volume. In compressor the inlet and outlet is different that means the volume does not remain constant. Compress...

Question is, when we use hydro fracturing treatment and when we use matrix Acidization treatment ? Answer is, when we have very low permeability from initially , and if we do only matrix acidzation, then it will only give us that low initial permeability back only. And if we do hydraulic fracturing , then it can give us more permeability than earlier. So, if our reservoir is having less than some threshold value of initial permeability, than we go for hydraulic fracturing. And if we have initial reservoir permeability greater than some values, than restoration of that permeability can also will lead to more production. So we go for matrix acidization, if we have good initial permeability. When we use matrix Acidization and when we use acid Fracturing ? We decide based on lithology first. We use Acid Fracturing in Limestone or Carbonate reservoirs only. And matrix Acidization is generally used in sandstone reservoirs. Another view of answering is, in low permeability reservoirs,...

What determines mobility or ability to move fluids from one pore to another pore or inside porous media ? First answer of all of us will be, Permeability. (Yes, that is main super hero for fluid to move.) So, higher the Permeability of fluid, higher ability to move fluid. Think about other factors. For ability to move in restricted environments,(like porous media here), if our fluid is more Viscous, then it will have less ability to move.  That is point where we all are agree. So, we have two terms, one with positive relation with ability to move fluid (that is permeability), and one with negative relation with same (Viscocity). So, if we want to define this ability to move fluid in one parameter, than can we do it ? Well, we can do it in simple way. Just make ability to move fluid proportional to permeability and inversely proportional to viscosity. And that will be our new parameter, which is essentially representing ability of movement or ability of fluid to be mobile (That's Mo...