# hello every present in Arab engineering



## hoodxx (14 ديسمبر 2010)

السلام عليكم يا اعضاء ملتقاء المهندسين 

اما بعد انا ادرس هندسة حفر ابار النفط ولدي صعوبة في الدراسة

وحل بعض الاسئلة لذا اردت منكم المساعدة في حل بعض الاسئلة

ومن يستطيع المشاركة ولو بشي القليل

ولكم جزيل الشكر والتقدير

وبتوفيق جميعا ان شاء الله

وهذ بعض الاسئلة​



Q1​ 1) Electing the drilling mud I one of the main tasks the engineer should do when he prepare the well plan. You are given all data required to help you in selecting the proper type of mud and you have a choice to elect water base mud or oil base mud. Explain the benefit of using each type of mud.​​ Applications-​​ Advantages and disadvantages of using oil mud-​​ -Additives used to control properties for each type( viscosity, filtration, density, alkalinity)​​ Environmental issues-​​ Well control issues-​​ Solid control equipment-​
​ 2) Drilling mud can be contaminated by different type of materials during drilling and cementing operations. So the mud engineer should prepares himself to maintain and cure the mud to minimize the effect of thee contaminants. If you have the following case; the lithological prognosis for this well contains the following formations;​​ Alt rocks, anhydrite, limestone, gypsum and shale.
​ And we planning to run and cement different size of casing.​ Explain and analyse the best drilling mud programme with the required additives to optimize and plan the bet drilling mud programme for drilling this well at the lowest cost.​
​ 3) Clear solids free brine have gained widespread acceptance as part of a general practice for completion and workover application. Because of their ability to meet the desired properties and performance.​​ - What do the term brines refer to?​​ - Discuss their desired properties and performance.​

​ 4) The PH is one important property of drilling fluids;​​ - Discuss polymers necessary to increase and decrease PH.​​ - What are the Advantages to increase PH above the neutral level.​
​ Q2​ 1) It is desired to decrease the density of mud from 10.2 ppg to 9.5 ppg adding 30 degree API oil to the mud. There are 900 bbs of mud in the system.​​ -Calculate the volume of oil required​ 
- what will be the percentage of oil in the mud.​​ 2) It is desired to increase the density of 1000 bbl of 11 ppg mud to 14 ppg. one gallon of water will be added with each sack of barite to prevent excessive thickening of the mud. A final mud volume of 1000 bbl is deired.​​ - Compute the volume of old mud that should be discarded.​​ - Compute the mass of barite to be added.​
​ 3) From laboratory data, it is found that 5.5 percent clay is required in clay fresh water suspension to produce viscosity of 15 cp. What I the yield of the clay in bbl of suspension per tow ton of clay.


​ 4) the drilling engineer is concerned with the selection and maintenance of the best drilling fluid for the job. To select the best fluid there are many factor that should be considered by the mud engineer. Explain how thee factor help in selecting the proper mud.​


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## مسعود الهنائي (16 ديسمبر 2010)

اجابة الاسئلة موجودة في المكتبة الي في كليتكم
الكلية الدولية للهندسة والادارة
انت ابحث وربنا راح يوفقك ان شاء الله
بس ما تكتب الاسايمنت كله في هذا النتدى وتبغى اجابة جازة كذا
تمام صديقي


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## hoodxx (16 ديسمبر 2010)

مسعود الهنائي قال:


> اجابة الاسئلة موجودة في المكتبة الي في كليتكم
> الكلية الدولية للهندسة والادارة
> انت ابحث وربنا راح يوفقك ان شاء الله
> بس ما تكتب الاسايمنت كله في هذا النتدى وتبغى اجابة جازة كذا
> تمام صديقي


 

تمام صديقي 
ومشكوررررررررررررررررررررررررررررر:20:


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## AIOI85 (8 يناير 2011)

thanx


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## jathmi2 (13 يناير 2011)

Advantages and disadvantages of using oil mudAdvantages and disadvantages of using oil mud
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Advantages
*[edit] Remove cuttings from well*

Drilling fluid carries the rock excavated by the drill bit up to the surface. Its ability to do so depends on cutting size, shape, and density, and speed of fluid traveling up the well (annular velocity). These considerations are analogous to the ability of a stream to carry sediment; large sand grains in a slow-moving stream settle to the stream bed, while small sand grains in a fast-moving stream are carried along with the water. The mud viscosity is another important property, as cuttings will settle to the bottom of the well if the viscosity is too low.
Other properties include:

Most drilling muds are thixotropic (that is, they become a gel under static conditions). This characteristic keeps the cuttings suspended when the mud is not moving during, for example, maintenance.
Fluids that have shear thinning and elevated viscosities are efficient for hole cleaning.
Higher annular velocity improves cutting transport. Transport ratio (transport velocity / lowest annular velocity) should be at least 50%.
High density fluids may clean hole adequately even with lower annular velocities (by increasing the buoyancy force acting on cuttings). But may have a negative impact if mud weight is in excess of that needed to balance the pressure of surrounding rock (formation pressure), so mud weight is not usually increased for hole cleaning purposes.
Higher rotary drill-string speeds introduce a circular component to annular flow path. This helical flow around the drill-string causes drill cuttings near the wall, where poor hole cleaning conditions occur, to move into higher transport regions of the annulus. Increased rotation are the best methods in high angle and horizontal beds.
*[edit] Suspend and release cuttings*


Must suspend drill cuttings, weight materials and additives under a wide range of conditions.
Drill cuttings that settle can causes bridges and fill, which can cause stuck-pipe and lost circulation.
Weight material that settles is referred to as sag, this causes a wide variation in the density of well fluid, this more frequently occurs in high angle and hot wells
High concentrations of drill solids are detrimental to:
Drilling efficiency (it causes increased mud weight and viscosity, which in turn increases maintenance costs and increased dilution)
Rate of Penetration (ROP) (increases horsepower required to circulate)
Mud properties that suspended must balanced with properties in cutting removal by solids control equipment

For effective solids controls, drill solids must be removed from mud on the 1st circulation from the well. If re-circulated, cuttings break into smaller pieces and are more difficult to remove.
Conduct a test to compare the sand ******* of mud at flow line and suction pit (to determine whether cuttings are being removed).
*[edit] Control formation pressures*


If formation pressure increases, mud density should also be increased, often with barite (or other weighting materials) to balance pressure and keep the wellbore stable. Unbalanced formation pressures will cause an unexpected influx of pressure in the wellbore possibly leading to a blowout from pressured formation fluids.
Hydrostatic pressure = density of drilling fluid * true vertical depth * acceleration of gravity. If hydrostatic pressure is greater than or equal to formation pressure, formation fluid will not flow into the wellbore.
Well control means no uncontrollable flow of formation fluids into the wellbore.
Hydrostatic pressure also controls the stresses caused by tectonic forces, these may make wellbores unstable even when formation fluid pressure is balanced.
If formation pressure is subnormal, air, gas, mist, stiff foam, or low density mud (oil base) can be used.
In practice, mud density should be limited to the minimum necessary for well control and wellbore stability. If too great it may fracture the formation.
*[edit] Seal permeable formations*


When mud column pressure exceeds formation pressure, mud filtrate invades the formation, and a filter cake of mud is deposited on the wellbore wall.
Mud is designed to deposit thin, low permeability filter cake to limit the invasion.
Problems occur if a thick filter cake is formed; tight hole conditions, poor log quality, stuck pipe, lost circulation and formation damage.
In highly permeable formations with large pore throats, whole mud may invade the formation, depending on mud solids size;
Use bridging agents to block large opening, then mud solids can form seal.
For effectiveness, bridging agents must be over the half size of pore spaces / fractures.
Bridging agents (e.g. calcium carbonate, ground cellulose).

Depending on the mud system in use, a number of additives can improve the filter cake (e.g. bentonite, natural & synthetic polymer, asphalt and gilsonite).
*[edit] Maintain wellbore stability*


Chemical composition and mud properties must combine to provide a stable wellbore. Weight of the mud must be within the necessary range to balance the mechanical forces.
Wellbore instability = sloughing formations, which can cause tight hole conditions, bridges and fill on trips (same symptoms indicate hole cleaning problems).
Wellbore stability = hole maintains size and cylindrical shape.
If the hole is enlarged, it becomes weak and difficult to stabilize, resulting in problems such as low annular velocities, poor hole cleaning, solids loading and poor formation evaluation
In sand and sandstones formations, hole enlargement can be accomplished by mechanical actions (hydraulic forces & nozzles velocities). Formation damage is reduced by conservative hydraulics system. A good quality filter cake containing bentonite is known to limit bore hole enlargement.
In shales, mud weight is usually sufficient to balance formation stress, as these wells are usually stable. With water base mud, chemical differences can cause interactions between mud & shale that lead to softening of the native rock. Highly fractured, dry, brittle shales can be extremely unstable (leading to mechanical problems).
Various chemical inhibitors can control mud / shale interactions (calcium, potassium, salt, polymers, asphalt, glycols and oil – best for water sensitive formations)
Oil (and synthetic oil) based drilling fluids are used to drill most water sensitive Shales in areas with difficult drilling conditions.
To add inhibition, emulsified brine phase (calcium chloride) drilling fluids are used to reduce water activity and creates osmotic forces to prevent adsorption of water by Shales.
*[edit] Minimizing formation damage*


Skin damage or any reduction in natural formation porosity and permeability (washout) constitutes formation damage
Most common damage;
Mud or drill solids invade the formation matrix, reducing porosity and causing skin effect
Swelling of formation clays within the reservoir, reduced permeability
Precipitation of solids due to mixing of mud filtrate and formations fluids resulting in the precipitation of insoluble salts
Mud filtrate and formation fluids form an emulsion, reducing reservoir porosity

Specially designed drill-in fluids or workover and completion fluids, minimize formation damage.
*[edit] Cool, lubricate, and support the bit and drilling assembly*


Heat is generated from mechanical and hydraulic forces at the bit and when the drill string rotates and rubs against casing and wellbore.
Cool and transfer heat away from source and lower to temperature than bottom hole.
If not, the bit, drill string and mud motors would fail more rapidly.
Lubrication based on the coefficient of friction. Oil- and synthetic-based mud generally lubricate better than water-based mud (but the latter can be improved by the addition of lubricants).
Amount of lubrication provided by drilling fluid depends on type & quantity of drill solids and weight materials + chemical composition of system.
Poor lubrication causes high torque and drag, heat checking of the drill string, but these problems are also caused by key seating, poor hole cleaning and incorrect bottom hole assemblies design.
Drilling fluids also support portion of drill-string or casing through buoyancy. Suspend in drilling fluid, buoyed by force equal to weight (or density) of mud, so reducing hook load at derrick.
Weight that derrick can support limited by mechanical capacity, increase depth so weight of drill-string and casing increase.
When running long, heavy string or casing, buoyancy possible to run casing strings whose weight exceed a rig's hook load capacity.
*[edit] Transmit hydraulic energy to tools and bit*


Hydraulic energy provides power to mud motor for bit rotation and for MWD (measurement while drilling) and LWD (logging while drilling) tools. Hydraulic programs base on bit nozzles sizing for available mud pump horsepower to optimize jet impact at bottom well.
Limited to:
Pump horsepower
Pressure loss inside drillstring
Maximum allowable surface pressure
Optimum flow rate
Drill string pressure loses higher in fluids higher densities, plastic viscosities and solids.

Low solids, shear thinning drilling fluids such as polymer fluids, more efficient in transmit hydraulic energy.
Depth can be extended by controlling mud properties.
Transfer information from MWD & LWD to surface by pressure pulse.
*[edit] Ensure adequate formation evaluation*


Chemical and physical mud properties and wellbore conditions after drilling affect formation evaluation.
Mud loggers examine cuttings for mineral composition, visual sign of hydrocarbons and recorded mud logs of lithology, ROP, gas detection or geological parameters.
Wireline logging measure – electrical, sonic, nuclear and magnetic resonance.
Potential productive zone are isolated and performed formation testing and drill stem testing.
Mud helps not to disperse of cuttings and also improve cutting transport for mud loggers determine the depth of the cuttings originated.
Oil-based mud, lubricants, asphalts will mask hydrocarbon indications.
So mud for drilling core selected base on type of evaluation to be performed (many coring operations specify a blend mud with minimum of additives).
*[edit] Control corrosion (in acceptable level)*


Drill-string and casing in continuous contact with drilling fluid may cause a form of corrosion.
Dissolved gases (oxygen, carbon dioxide, hydrogen sulfide) cause serious corrosion problems;
Cause rapid, catastrophic failure
May be deadly to humans after a short period of time

Low pH (acidic) aggravates corrosion, so use corrosion coupons to monitor corrosion type, rates and to tell correct chemical inhibitor is used in correct amount.
Mud aeration, foaming and other O2 trapped conditions cause corrosion damage in short period time.
When drilling in high H2S, elevated the pH fluids + sulfide scavenging chemical (zinc).
*[edit] Facilitate cementing and completion*


Cementing is critical to effective zone[_clarification needed_] and well completion.
During casing run, mud must remain fluid and minimize pressure surges so fracture induced lost circulation[_clarification needed_] does not occur.
Mud should have thin, slick filter cake, wellbore with no cuttings, cavings or bridges.[_clarification needed_]
To cement and completion operation properly[_clarification needed_], mud displace by flushes and cement.[_clarification needed_] For effectiveness;
Hole near gauges[_clarification needed_]
Mud low viscosity[_clarification needed_]
Mud non progressive gel strength[_clarification needed_]

*[edit] Minimize impact on environment*

Mud is, in varying degrees, toxic. It is also difficult and expensive to dispose of it in an environmentally friendly manner. A Vanity Fair article described the conditions at Lago Agrio, a large oil field in Ecuador where drillers were effectively unregulated. Texaco, the drilling company, left the used mud (and associated cuttings and crude oil) in unlined open-air pits, allowing it to contaminate both surface and underground waters. Storing mud properly is very expensive. After a decade of drilling, Texaco considered transferring the mud waste at Lago Agrio to concrete-lined pits, but estimated that it would cost over 4 billion dollars (US).[_citation needed_]


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## muhjm (21 مايو 2011)

السلام عليكم
الى الاخوة الاعزاء في هذا المنتدى الراقي
ارجوا مساعدتي في حل الاخطاء الموجودة في هذا البرنامج في الماتلاب


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