Wireline Logs

1. INTRODUCTION

Well logging is an interesting method that deals with the subsurface layers providing every necessary detail required about them. The process basically involves specialized tools which are sent down through the well bore to gather the information about the subsurface properties. This data collected is represented over a series of measurements covered over the depth range of the well bore and this assimilation is collectively known as well logs.

The first well log was made in 1927 at Pechelbronn Field in Alsace, France. Invented by the Schlumberger brothers, Marcel and Conrad, the tool measured the electrical resistance of the earth’s subsurface. They recorded the data at each meter as they retrieved the sonde, a specialized tool suspended from the cable, from the borehole. This data log of the corresponding resistivity change was used to identify the location of oil.

The well logs are useful in defining a number of parameters that include physical rock characteristics, lithology, mineralogy, pore geometry, porosity and permeability. By interpretation of the well log data we can also estimate the productive zones with their thickness and depth by defining the basic parameters like fluid composition and relative saturation. The other prominent methods that involve the well data is relating them to seismic to obtain a proper correlation pattern that will help in confirming the hydrocarbon presence.

For oil and gas prospecting the well data helps in the rock type identification of geological environment, reservoir fluid contact location and fracture detection. One can also estimate the total hydrocarbon in place along with the recoverable hydrocarbon. Determination of water salinity, reservoir pressure, porosity or pore size distribution is also done with its help. The other properties that can be interpreted from the data are water flood feasibility, reservoir quality mapping, interzone fluid communication probability and reservoir fluid movement monitoring.

Applications of well logging data differ according to the specified specializations.

For the Geologist:
1.Depths of formation tops.
2. Geological environment and hydrocarbon accumulation.
3. Presence of hydrocarbons and its quantity.4.What are the reserves?
5. Conditions for an offset well.

For the Geophysicist: 
1.Predicted formation tops.
2. Potential zone analysis for properties such as porosity as assumed from seismic data.
3. Analysis of synthetic seismic sections.

For the Drilling Engineer:
1.Hole volume for cementing.
2. Presence of any Key-Seats or severe Dog-legs.
3. Location for a good packer seat for testing.
4. Location to set a Whipstock.

For the Reservoir Engineer:
1.Thickness of pay zone.
2. Homogeneity of the section.
3. Volume of hydrocarbon per cubic meter.
4. Duration of well pay-out.

For the Production Engineer:
1.Determination of well completion zones.
2. Expected production rate.
3. Chances for water production.
4. Suitable well completion methods.
5. Determination of hydraulically isolated potential pay zone.

2. Methods of Logging

Open-hole Logging

• Performed on a well before the wellbore has been cased and cemented.
• Logging is done through the bare rock sides of the formation.
• Common type of logging method because the measurements are not obstructed.
• Done during or after the well has been drilled.

Cased-hole Logging

• Retrieve logging measurements through the well casing, or the metal piping that is inserted into the well during completion operations.
• Cased-hole logging is performed more rarely but it provides valuable information about the well.

This chart is separated into three concentric areas: the middle annular area indicates the subsurface properties to be evaluated, the innermost area indicates the specialized logging tools, and the outermost area indicates other logging tools.

3. Log Types

The following are the most important type of logs:

1. Electric logs – self potential, resistivity and conductivity logs. Electric logs were the first type to be employed in petroleum exploration, because it was fairly simple to make the measurements. This involved measuring the electric resistance (R) (resistivity) and the current that is set up between the drilling mud and the porewater in the rock (formation), i.e. the self-potential (SP).

2. Radioactivity logs - gamma ray and neutron logs. Gamma logs measure the natural emission of gamma rays from rocks in well. A neutron log is obtained y using neutron source which sends radiation into the rocks. The absorption, mostly by hydrogen atoms, occurring in water and hydrocarbons is then measured.

3. Acoustic (sonic) logs – measure how fast sound travels through rocks, and in particular provide information about porosity. This also indicates whether a liquid or gas phase occupies the pore spaces.

4. Dipmeter logs – a type of electric log which measures the slope of beds and lamination in rocks.

Logs which directly measure properties of the well itself:

- Caliper logsregister variations in the diameter of the well.

- Temperature logs record borehole temperature and can be used to calculate the true formation temperature.

- Image logs provide a picture of the well wall and may reveal layering, sedimentary structures and fractures

3.1. Electric Logs

Spontaneous Potential

• SP logs record the electrical current (in milivolts) that arises due to salinity differences between a salt water based drilling mud and the fluid in formation.
• Indicate permeability of rocks by measuring voltage difference between the drilling fluid and formation water.
• Can distinguish shale from carbonates and sandstones.
• Porous sandstones with high permeability generate more electricity than shale
• Shale positive; sand negative.
• Shale has values between 0 to -20 mV, sandstones and carbonates typically have values between -20 to -80 mV.
• Identifies permeable zones and boundaries
• Not good indicator of lithologic boundaries.

Typical responses of the SP Log

Permeability recognition by SP Log

Resistivity Log

• Resistivity is the physical property of a formation which impedes the flow of electric current.
• Distinguishes type of fluid; hydrocarbon, fresh water and brine
• Measures the effectiveness of rocks in conducting electricity
• Short penetration reflects drilling mud; longer is due to formation of water
• It is base on Induction Principle.
• Low resistivity means shale/ wet sand; high resistivity means hydrocarbons
• Resistivity is measured by drilling tools like DLL, HRI, HRAI etc.
• Application:
• Determines the true resistivity of formation
• Indicated presence of movable hydrocarbons

Typical Resistivity Log Response

3.2. Acoustic Logs

• Petroleum applications of acoustic-wave-propagation theory and physics include both:
  • Surface-geophysical methods
  • Borehole-geophysical methods
• Measures a number of sonic parameters like compressional & shear velocities and travel time.
• Determines porosity by measuring the speed of sound waves in the formation.
• Identify zones with abnormally high pressures.
• Identification of gas-bearing intervals.
• Estimate rock permeability.
• Cement Evaluation.
• Improve correlation and interpretation of seismic records.
• Help in identifying lithology and fractures.
• Helps in Geophysical Interpretation like Synthetic Seismograms, VSP, AVO Analysis, etc.
• Study of rocks mechanical properties and acoustic impedance (in combination with the density log).
• Displays travel time of P-waves versus depth.
• They are recorded by pulling a tool on a wireline up the wellbore.
• Tool emits a sound wave that travels from source to the formation and back to the receiver.
• Tool measures the time it takes for a pulse of sound to travel from a transmitter to receiver. Both of which are mounted on the same tool.
• The transmitted pulse is very short and of high amplitude. The wave travels through different forms like dispersion and attenuation occurs.
• When the sound energy arrives at receiver, it captures them at different times in the form of different types of waves.
• Travel time is the difference in the arrival of compressional waves at the receivers.

Typical responses of the Sonic Log

Log presentation for the GNT Tool

3.3. Nuclear Logs

Neutron Logs

• Determines porosity by measuring the amount of hydrogen atoms (neutrons) in the pores.
• Tool has a neutron source.
• Hydrogen absorbs neutrons and emits Gamma rays.
• Hydrogen is mostly found in formation fluids like water or hydrocarbons.
• Can be run in Cased holes.

Neutron Curve

• Measures effect of bombarding a formation with a strong source of neutrons. This bombardment upsets the radioactive equilibrium of the rocks in the bore hole and induces a secondary gamma ray intensity many times greater than the natural gamma ray radiation from these rocks.
• Generally appears similar to resistivity curve of electrical log. Different neutron values due to presence of fluid will alter this similarity somewhat.
• Does not represent lithology.
• Is difficult to interpret alone.
• Cannot be always correlated because it represents primarily fluid content.
• Shale is normally the lowest curve value. This is due to the presence of hydrogen in the shale that slows the fast neutrons and reduces the incidence of capture, with resulting low secondary gamma ray radiation.
• Shales may be used as a base line for curve.
• Is not generally affected by highly radioactive formations.

Tool Operation:

• The tool operates by bombarding the formation with high energy neutrons. These neutrons undergo scattering in the formation, losing energy and producing high energy gamma rays. The scattering reactions occur most efficiently with hydrogen atoms. The resulting low energy neutrons or gamma rays can be detected, and their count rate is related to the amount of hydrogen atoms in the formation.
• In formations with a large amount of hydrogen atoms, the neutrons are slowed down and absorbed very quickly and in a short distance. The count rate of slow neutrons or capture gamma rays is low in the tool. Hence, the count rate will be low in high porosity rocks.
• In formations with a small amount of hydrogen atoms, the neutrons are slowed down and absorbed more slowly and travel further through the rock before being absorbed. The count rate of slow neutrons or capture gamma rays in the tool is therefore higher. Hence, the count rate will be higher in low porosity rocks.
• There are mainly three types of neutron tool, which are:
  • The Gamma Ray/Neutron Tool (GNT)
  • The Sidewall Neutron Porosity Tool (SNP)
  • The Compensated Neutron Log (CNL)

Typical neutron log responses in common lithologies

Density or Porosity Logs

• Determines porosity by measuring electron density.
• Dense formation absorbs more gamma rays while low-density formations absorb fewer.
• High court rate at detector means low-density formation.
• Mineral identification.
• Gas detection (used in combination with neutron log).
• Shale gas evaluations.
• Delineate thin beds.
• The formation density is a porosity log that measures electron density of a formation.
• The gamma rays enter the formation and undergo compton scattering by interaction with the electrons in the atoms composing the formation.
• Compton scattering reduces the energy of the gamma rays in a step-wise manner, and scatters the gamma rays in all directions.
• When the energy of the gamma rays is less than 0.5 MeV they may undergo photo-electric absorption by interaction with the atomic electrons.
• The flux of gamma rays that reach each of the two detectors is therefore attenuated by the formation, and the amount of attenuation is dependent upon the density of electrons in the formation.
• Dense formations absorb many gamma rays, while low-density formations absorb fewer. Thus, high-count rates at the detectors indicate low-density formations, whereas low count rates at the detectors indicate high-density formations.
• Therefore, scattered gamma rays reaching the detector is an inclination of formations density.
• Scale and units: The most frequently used scales are a range of 2.0 to 3.0 gm/cc or 1.95 to 2.95 gm/cc across two tracks.

The tool consists of:

• A radioactive source: This is usually caesium-137 or cobalt-60, and emits gamma rays of medium energy (in the range 0.2 – 2 MeV). For example, caesium-137 emits gamma rays with a energy of 0.662 MeV.
• A short range detector. This detector is very similar to the detectors used in the natural gamma ray tools, and is placed 7 inches from the source.
• A long range detector. This detector is identical to the short range detector, and is placed 16 inches from the source.

Schematic diagram of a formation density tool.

Gamma Ray Log

• Measures radioactivity to determine the kind of rocks.
• Decay of radioactive elements produces high energy gamma ray.
• This gamma radiation originates from potassium-40 and the isotopes of the Uranium-Radium and Thorium series.
• Once the gamma rays are emitted from an isotope in the formation, they progressively reduce in energy as the result of collisions with other atoms in the rock (compton scattering).
• Compton scattering occurs until the gamma ray is of such a low energy that it is completely absorbed by the formation.
• Hence, the gamma ray intensity that the log measures is a function of:
  • The initial intensity of gamma ray emission, which is a property of the elemental composition of the rock.
  • The amount of compton scattering that the gamma rays encounter, which is related to the distance between the gamma emission and the detector and the density of the intervening material.
  • The tool therefore has a limited depth of investigation.

• Shale show high radioactivity as radioactive elements are concentrated in Shale
• Sandstone and carbonate usually show low radioactivity.
• Can be run in both open and cased hole.

Gamma Ray Curve

• Measure the natural gamma ray radiation from the formation. No electrical properties are measured.
• Generally appears similar to self potential curve of the electrical log.
• Formations generally have a characteristic curve response according to type.
• Can be readily interpreted alone in most areas.
• Can be readily correlated with other information pertaining to the formation type.
• Shale is normally the highest curve value.
• No base line or zero. All recordings are positive.
• Is greatly affected by highly radioactive formations.
• Is not affected by changes in borehole diameter.
• Id not affected by borehole and formations fluid.
• Does not represent porosity or permeability.

Gamma Ray Spectral Log Presentation.

3.4. Other Logs

NMR (Nuclear Magnetic Resonance) Logs

• Measures magnetic response of fluids.
• Measures both porosity and permeability.
• Help determining the type of fluid in pore spaces.
• Identify low-resistivity pay within water volumes.

Dipmeter Logs

• Determines orientations of sandstone and shale beds.
• Determines orientations of faults and fractures.
• Measures resistivity of rocks.
• Make detailed image of the rock around the well hole.

Image Logs

• High resolution images of the borehole.
• Electrical micro imaging technique.
• Used to identify a variety of geological attributes like structural dip, faults and fractures.
• Insight to the condition of the borehole, stress and rock mechanics around the borehole.
• Helps in porosity determination.
• Recent developments in LWD made it possible to acquire high resolution electrical borehole images. In real time these images can help to steer the drill bit.
• Applications:
  • Detailed stratigraphic and sedimentological analysis.
  • This bed delination.
  • Fault mapping and structural analysis.

Caliper Logs

• Measure the diameter and shape of a borehole.
• Indicator of good permeability and porosity zones.
• Calculation of mudcake thickness.
• Measurement of borehole volume.

Typical caliper responses to various lithologies.

IIT JEE main 2014 result out - Check Here

Click here to check the result.

Hello friends, aspirants of JEE 2014 ( Joint Entrance Examination 2014) were eagerly waiting for the result of the JEE main 2014. On 3rd may 2014 the result of the JEE main was declared and aspirants can check their result by entering roll number and date of birth.

JEE is a All India Entrance for the admission in various IIT's and ISM, Dhanbad. This is about getting the best college for pursuing Engineering to build a successful and fruitful career ahead. Every year Lakhs of student appear in JEE examination and just few get selected to study in the top IIT's.

Download your score card from the official website of the JEE main 2014 i.e. http://cbseresults.nic.in/jee/jee_cbse_2014.htm

You can also click here to check the result. All the best!

Chelsea vs Atletico Madrid (1-3) 2014 Goals and Highlights |30/4/2014|

FACTS:

Chelsea vs Atletico Madrid (1-3) Semi Final

Chelsea: Schwarzer 6, Ivanovic 6.5, Cole 6 (Eto'o 54, 5), Luiz 7, Cahill 6, Terry 6.5, Azpilicueta 6.5, Ramires 6.5, Torres 6.5 (Ba 67, 5), Willian 6.5 (Schurrle 77), Hazard 6

Subs not used: Oscar, Van Ginkel, Kalas, Hilario

Goal: Torres 36

Booked: Cahill

Manager: Jose Mourinho 6.5

Atletico Madrid: Courtois 6.5, Juanfran 7, Luis 7.5, Tiago 7, Miranda 7, Godin 7, Turan 7 (Rodriguez 84), Suarez 7, Adrian 7 (Raul Garcia 66), Costa 8 (Sosa 76), Koke 7.5

Subs not used: Aranzubia. Villa, Alderweireld, Diego

Goals: Adrian 44, Diego Costa 60, Turan 72

Booked: Adrian, Diego Costa

Manager: Diego Simeone 8

Referee: Nicola Rizzoli 6.5

Movie Review: Revolver Rani

Cast: Kangana Ranaut, Vir Das, Zakir Hussain, Zeishan Quadri 
Director: Sai Kabir Shrivastav 
Producer: Tigmanshu Dhulia 
Music: Sanjeev Srivastava 
Writer: Sai Kabir Shrivastav

When it’s a mad, mad, mad world, trust Kangana Ranaut to tug out the stops. 

As the trigger-happy ‘hero’ of Revolver blue blood, the uncontrolled lead actor dives head 1st into the deep finish of the ethical cesspit that writer-director Sai Kabir conjures up in his 1st free film. 

Alka Singh of Morena is not any normal rural area hell-raiser. She flashes gold-bearing bustiers, sports her trademark nappy hair style, and takes on a noticeably darkened skin tone.

Kangana’s character could be a fire-spewing attacker who nurses a secret need to be a mother and a hausfrau. whereas she lets her gun do abundant of the talking on her behalf, she aspires for the straightforward joys of womanhood. 

The film flits from the non-public to the political, the emotional to the glaring, and also the absurd to the deadly serious. For the foremost half, Revolver blue blood hits the bull’s eye. 

It is each hilariously funny and deeply disturbing: simply the type of fabric that's right up Kangana Ranaut’s street. 

She doesn’t miss one aggregation on the manner, rampaging through a twisted narrative within which electoral contests and gang wars ar indistinguishable from one another. 

As Kangana bares the mangled soul of the eponymic heroine, she turns what's by no suggests that a unflawed film into a ballsy ballad of the Bhind-Morena badlands wherever dangerous plots ar hatched, bullets ar dismissed and blood is spilled at the drop of a hat.

Kangana, contemporary from a queen-sized box workplace triumph, embraces this blue blood with all the facility that she will be able to muster. 

The result's a high-on-adrenaline heroine who thrives on overdrive, the type that went out of vogue with Fearless Nadia and Hunterwali.

No, Revolver blue blood, for all its retro vogue and ingredients, is never that ancient in spirit and substance. 

But it will draw heavily from recent Hindi picture show traditions whereas fully destruction the dependence of the political adventure story on typical masculinity. 

Sai Kabir’s wicked battle the turbulent lifetime of a hell’s angel in an exceedingly man’s world is that the medium equivalent of a smorgasbord. 

Its nods ar directed at various genres – noir, payback heroic tale, comic caper, political sarcasm, imitation legend, and an honest recent tale of courageousness within the face of maximum danger.

These ar smartly stirred into associate degree revitalis cocktail that stands out primarily as a result of at the center of it all is associate degree unstoppable  woman who pulls no punches.

The protagonist could be a feisty politician whose instrument runs across city. 

Her opponent, Udaybhan Singh (Zakir Hussain), and his bungling men ar perpetually at the receiving finish of Alka’s no-holds-barred political sorties.

They arrange ways that to eliminate her, however the woman and her principal consultant, the injured Balli Mama (Piyush Mishra), ar so much too cunning for the half-baked machinations of their adversaries. 

The romantic interest is provided by a applier Bollywood actor Rohan Kapoor (Vir Das). 

He strays into the lifetime of Alka Singh hoping to any his probabilities of constructing it as a star. however that basically is that the finish of the road for the guy.

It is a unidirectional street that leads either to the raging fireplace of hell or to the salubrious canals of city. Alka digs each, all things Italian and everything that smells of bother.

Revolver blue blood includes a delightfully humourous parallel track that takes aim at the manipulations of the media.

A news reader seems at crucial points within the plot within the manner of a classic sutradhar and launches into over the highest descriptions of the shenanigans of the powerful. 

She takes recourse to distorted poetry, film lyrics and snatches of Hindi literary composition dialogue to form her purpose. gratuitous to mention, she is everywhere the place.

The film additionally alludes to corruption in, and also the human value of, the indiscriminate acquisition of social group land at the command of huge trade.

Mercifully, Revolver blue blood isn't a case of associate degree vaulting writer-director biting off over he will chew. 

The script stays on the right track even once the drama teeters on the sting of the atrociously outre. 

Kangana lends a crepitation and corrosively sharp edge to the central character of a tough-as-nails girl in an exceedingly mug’s game. 

Vir Das could be a total anomaly during this world. however that's specifically what he's meant to be – a person WHO is out of his depth within the rough and tumble of the rural area.

Zakir Hussain is absolutely forged because the strongman who is forever on the rear foot. He moves back and forth between fanfare and bewilderment with easy ease.

Also noteworthy is Piyush Mishra’s characteristically consistent performance.

A Kangana Ranaut film looks to be progressively effort the proportions of a genre unto itself. 

It wants neither vendable male co-stars nor the tried-and-tested conventions of Bollywood blockbusters. 

Revolver blue blood could lack star power, however it's no dearth of military strength. 

Tito Vilanova: Barcelona's Former Manager Dies Aged 45

Supporters of Roma and Milan paid tribute to the former Barcelona coach Tito Vilanova at their Serie A match on Friday night. Photograph: Maurizio Brambatti/EPA

On the eve of Tito Vilanova's initial season responsible of metropolis, he stood within the middle of the Camp Nou pitch with a microphone in hand. Tradition dictates that the new campaign is welcome with the Gamper Trophy and therefore the manager perpetually features a message to deliver. This time, in August 2012, it carried a special affective power. "I'm thus happy that you are here with US," Vilanova turned to inform the French defender Eric Abidal. "Your fight is our strength."

Abidal had undergone a liver transplant in April of that year once suffering cancer and Vilanova knew one thing of what the Frenchman was going through: in November 2011 he had been diagnosed with cancer of the parotid gland within the throat whereas assistant manager to ginger Guardiola. the subsequent might it absolutely was formally declared that he had absolutely overcome the health problem and he looked forward to a future as the manager of the club. His club. Abidal was still sick from the operation, his future unsure.

"If you are sturdy and you've got desire," Vilanova told Abidal ahead of the fans, "we can anticipate you, as long as it takes."

Abidal was given the medical all-clear and came to the club's Sant Joan Despí coaching ground four months later. it had been Dec 2012. a similar day, it was declared that Vilanova had suffered a relapse of his cancer. He underwent radiotherapy and chemotherapy whereas still the Barcelona manager, eventually being forced to leave the post last summer attributable to his deteriorating health. On Friday, he passed away. He was 45.

Flags at the executive entrance to the Camp Nou flew at half-mast. somewhat more spherical, aboard the north finish of the bowl, stands La Masía – the tiny Catalan-style farmhouse built in 1702 where the club's youth team players used to live. it had been there that Vilanova watched out of the window as Bernd Schuster trained on the little pitch below and there that he met Guardiola. Vilanova had arrived aged fourteen and therefore the 2 men – 2 boys – were technically talented midfielders who shared abundant. Above all, they shared a philosophy.

Vilanova contend for Barcelona B but not the primary team. Born within the village of Bellcaire d'Empordà with a population of very little over five hundred, in Catalan agricultural country, Vilanova contend at Figueres, Celta DE Vigo, Badajoz, Mallorca, Elche and Gramenet. He had left Barcelona in 1990, determined that he wouldn't wait over 2 years for a chance nevertheless his vogue was perpetually a Barça vogue and he came swiftly. In 2002, he became coach of Barcelona's Cadete B, a team of 13-year-olds that enclosed Gerard Piqué, Cesc Fábregas and Lionel Messi.

When Guardiola was created coach of Barcelona's B team in 2007, he now referred to as his friend. Vilanova knew Catalan soccer like few others: he had been sporting director at Figueres and Terrasa and was coaching job at Palafrugell. He was a fair additional determined defender of a selected footballing religion than Guardiola, telling El País: "We're totally different. Winning alone isn't enough: we've a perfect of youth team players and assaultive soccer, as Barcelona's culture demands. we've our faults however being cowards can ne'er be one among them."

Together they won the Third Division league title so they took over the primary team. "Are we prepared for this?" Guardiola asked Vilanova. "Well, you are," Villanova replied. They won six out of six trophies, as well as a unique treble, and oversaw the foremost flourishing era within the club's history.

When Guardiola won the coach's Ballon d'Or, he dedicated the award to Vilanova, delivering the foremost personal part of his speech in Catalan. Vilanova had by then been diagnosed with cancer however he came back to figure in eighteen days. "My job is my whole life," he would say. And as Guardiola's time came to an end, he had overcome the health problem and was given the prospect to manage alone.

In a tv interview that winter, Vilanova explained however how treatment he had thought of his 2 kids who "still want me around". His son Adrià plays for Barcelona's juvenil youth team. a couple of days later, on what ought to have been a cheerful day, marked by Abidal's come back, the news bust. He traveled to ny for treatment, briefly leaving the post, returning to check Barcelona win the league title with a record a hundred points.

As Barcelona's kind had swaybacked and criticism had emerged at the top of that season, once Vilanova managed the team from his hospital bed, even conducting some team talks by video from the United States, Javier Mascherano noted: "Our manager isn't in ny on vacation, you know." Somehow it ne'er quite feels real, therefore the Argentinian's words hit hard. the headscarf Vilanova had taken to carrying round his neck was another reminder. Then, within the summer he was forced to step down as manager on medical recommendation.

There were occasional updates and he would be seen generally looking at his son however he had for the most part withdrawn, determined to not burden others. "It'll be fine," he would say.

On that Dec day once Barcelona declared Vilanova had suffered a relapse of the cancer to that he lost his life , the sporting director, Andoni Zubizarreta, was asked if Abidal and Vilanova's sicknesses made Barcelona's legend even bigger as a result of that they overcame adversity. "No," Zubizarreta replied, "it makes US human."