Concepts.for.GATE

After some time of production, when production rate decreases below our expectations, then we can say that, there is problem in our well. We diagnose our well for problem, whether problem is in our tubing or inside reservoir ? If we have tubing problem, like paraffin disposition, then we can remove it by Hot oil circulation or we can do, mechanical scraping with mechanical cutters. When we have problem in reservoir, then we can not do direct mechanical scraping or cutting. (Its obvious, we can not go at nano to micro pore levels to do scrapping.) So, we do it by other means. If we find, it is reservoir problem, then we do further study to identify exact problem.  If problem found out is, choking of pores due to any rock materials or solids, then then we can not do direct mechanical scraping or cutting. (Its obvious, we can not go at nano to micro pore levels to do scrapping.) So, we do it by other means. We have two options to remove this formation damage. First is, Acidization and...

Survey calculation methods : 1) Average angle method 2) Tangential method 3) Balanced tangential method (rarely used) 4) Radius of curvature method; and  5) Minimum curvature methods. For any Survey calculations. first, please see following Diagram. Lets understand this. First start with line (1) to (2). this line is making inclination angle ( α) with true vertical depth. so, here Sin ( α) = X/MD, So, X = MD* Sin ( α) Cos ( α) = TVD/MD, So, TVD = MD* Cos ( α) Now, look at line (1) to (3). this line is making Azimuth angle ( β )  with North direction. so, here Sin ( β )  = E/X, (a nd  X = MD* Sin ( α)) so, E =   MD* Sin ( α)* Sin ( β ) Cos ( β )  = N/X ,  ( and  X = MD* Sin ( α)) SO,  N = MD * Sin ( α)* Cos ( β ). So, We have, TVD = MD* Cos ( α), E =   MD* Sin ( α)* Sin ( β ), N = MD* Sin ( α)* Cos ( β ). This is Tangential method of calculation.  For all other methods, we use two inclination and azimuth angles. (one iis at upper po...

There are three types of translation movements (Movements in X, Y and Z directions). 1) Surge (Back and Forth) 2) Sway (Side and Side) 3) Heave (Up and Down) See this for explanation Surge movement Heave Movement of ship Sway movement of Red car (While accident) Surge moment of car There are three types of Rotational movements. 1) Pitch 2) Roll 3) Yaw Result of Pitch movement (ship) Pitch and Roll movements Roll movement Roll movement Yaw movement Surge and Heave movements (Combined) Click on icons to follow Us.

What is capillary number ? It is ratio of two forces. One is viscous force and another one is interfacial or surface tension force. So, it is ratio of viscous to interfacial tension force. (The  viscous force  can be calculated by multiplying the shear stress acting on the surface by the fluid and the area. The shear stress caused due to the  viscosity  of the fluid is directy proportional to the coefficient of  viscosity  of the fluid and the velocity gradient.) So, Capillary number NC = ( µ)*(v)/( σ) Where,  µ is dynamic viscosity of injecting fluid. v is superficial velocity of injecting fluid. σ is interfacial tension between injecting and displacing fluid . (N/m).  Before explanation, things we all will be agree are. i) As we have thick injection fluid, it can sweep our oil easily from oil reservoir in enhanced oil recovery/flooding processes.  ii) More the miscibility between injecting and production fluids, higher the recovery will be...

Klinkenberg (1941) discovered that permeability to gas is relatively higher than that to liquid, and he interpreted this phenomena as “ slip flow ” between gas molecules and solid walls.  Gas molecules collide each other and to pore-walls during traveling through the pore medium. When the pore radius approaches to the mean free path of gas molecules, the frequency of collision between gas molecules and solid walls increases . Therefore this additional flux due to the gas flow at the wall surface, which is called “slip flow”, becomes effective to enhance the flow rate. This phenomenon is called Klinkenberg effect, and its effect is expressed as follows,  where kg is permeability to gas (m2), kl is permeability to liquid (m2), l is mean free Path of the gas molecules (m), r is pore radius (m), κ is Boltzmann’s constant (JK−1), T is temperature (K), c is constant, p is pore pressure (Pa), b is Klinkenberg slip factor (Pa). The third term in Eq. (above) is given by the following relatio...

Landing nipple : It is a  completion  component fabricated as a short section of heavy wall pipe. It is fitted in between two tubing joints.  Landing nipples are included in most completions at predetermined intervals to enable the installation of flow-control devices, such as plugs and chokes. It has machined internal polished surface that provides a  seal  area and a locking profile to fit valves or plug inside tubing.  For locking profile, it has different arrangements. (See images) Three basic types of landing  nipple are commonly used in industry:  1) No-go nipples,  2) Selective-landing nipples and  3) Ported or safety-valve nipples. No  go landing nipple :  As name suggests, plugs or completion equipments can not completely go or pass through it. It has restricted part in its design, which will not allow most of competition equipements through it. so. this is nipple that incorporates at least one reduced diamet...

(i) Total porosity : Total porosity is defined as the fraction of the bulk rock volume V that is not occupied by solid matter.  (ii) Connected porosity: The ratio of the connected pore volume to the total volume.  (iii) Effective porosity: The same as the connected porosity.  (iv) Primary porosity: The porosity of the rock resulting from its original depositional structure.  (v) Secondary porosity: The porosity resulting from diagenesis.  (vi) Microporosity: The porosity resident in small pores (< 2 mm) commonly associated with detrital  and authigenic clays.  (vii) Intergranular porosity: The porosity due to pore volume between the rock grains.  (viii) Intragranular porosity: The porosity due to voids within the rock grains.  (ix) Dissolution porosity: The porosity resulting from dissolution of rock grains.  (x) Fracture porosity: The porosity resulting from fractures in the rock at all scales.  (xi) Intercrystal porosity: ...