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DICTIONARY OF PETROLEUM EXPLORATION, DRILLING & PRODUCTION Second Edition NORMAN J. HYNE, PH.D. DICTIONARY OF PETROLEUM EXPLORATION, DRILLING & PRODUCTION Second Edition NORMAN J. HYNE, PH.D. Disclaimer The recommendations, advice, descriptions, and the methods in this book are presented solely for educational purposes. The author and publisher assume no liability whatsoever for any loss or damage that results from the use of any of the material in this book. Use of the material in this book is solely at the risk of the user. Copyright© 2014 by PennWell Corporation 1421 South Sheridan Road Tulsa, Oklahoma 74112-6600 USA 800.752.9764 +1.918.831.9421 [email protected] www.pennwellbooks.com www.pennwell.com Marketing Manager: Amanda Brumby National Account Executive: Barbara McGee Director: Mary McGee Managing Editor: Stephen Hill Production Manager: Sheila Brock Production Editor: Tony Quinn Book Designer: Susan E. Ormston Library of Congress Cataloging-in-Publication Data Hyne, Norman J. [Dictionary of petroleum exploration, drilling & production] Dictionary of petroleum exploration, drilling, and production / Norman J. Hyne. -- 2nd edition. pages cm Revision of: Dictionary of petroleum exploration, drilling & production. ?1991. ISBN 978-1-59370-313-4 1. Petroleum--Dictionaries. 2. Petroleum engineering--Dictionaries. I. Title. TN865.H96 2013 622’.338203--dc23 2013023126 All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transcribed in any form or by any means, electronic or mechanical, including photocopying and recording, without the prior written permission of the publisher. Printed in the United States of America 1 2 3 4 5 18 17 16 15 14 Contents Dictionary of Petroleum, Exploration, Drilling & Production 1 Abbreviations 609 Petroleum Related Organizations 743 Appendix Abbreviations Used in This Text 751 Rotary Drilling Rig Parts 752 Cable Tool Drilling Rig Parts 753 Cranked Counterbalanced Beam Pumping Unit Parts 754 Common Geological Map Symbols 755 Common Geological Symbols for Rocks 756 Drillstem Test Symbols 759 Land Subdivisions (United States) 760 Geological Features (United States and Canada) 762 Atomic Weights and Numbers 769 Greek Alphabet 769 About the Author 771 Aalenian | absolute open flow 1 during and subsequent to its formation. Upward-migrating A A methane was affected by heat and pressure to form higher hydrocabons. This theory was proposed by Alexander von Humbolt in 1804 and was most popular in Russia and the B Ukraine during the mid-20th century. [Cf. biogenic theory] abnormal event recorded seismic energy that is not a direct C reflection such as a multiple, refraction, surface wave, or Aalenian global age of geological time ~174–170 million diffraction (noise) years ago. It is part of the Jurassic Period. D abnormal high pressure subsurface fluid pressure higher abaft directed toward the stern, or back, of an offshore than normal hydrostatic pressure at that depth. It can occur drilling rig or drillship in reservoirs that are sealed either by surrounding rocks such E as shales or by faults that prevent fluids from being expelled abandon 1) to permanently cease petroleum production from the reservoir during burial. Lithostatic pressure is then from a well, followed by plugging of the well. Injection, service, F transferred to fluid pressure. Overpressure is the excess observation, and water wells can also be abandoned. 2) to not pressure above normal pressure. Abnormal high pressure attempt completion of a well, declaring it a dry hole. This is in contrast to temporarily shutting in a well that can later be put reservoirs have relatively low seismic velocities and low densi- G ties. [Cf. abnormal low pressure] back on production. abnormal low pressure subsurface fluid pressure that is abandoned & junked a well abandoned because of mechan- H lower than normal hydrostatic pressure at that depth. This can ical problems (lost well) be caused by erosion through removal of overlying sedimen- abandoned & whipstocked a well that was drilled and was tary rocks, as a result of which the reservoir rock expands I then plugged back and had another wellbore drilled from it by in volume. Underpressure is the amount of pressure below whipstock ABW hydrostatic pressure. (subnormal pressure) [Cf. abnormal J high pressure] abandoned oil crude oil that has leaked from a pipeline or tank that the operator has made no effort to recover abnormal pressure or abnormal pore pressure pore pressure greater or lower than normal hydrostatic pressure for K abandoned pressure see abandonment pressure that depth abandoned well 1) a well that has been drilled as a dry hole and is going to be or has been plugged 2) a well that no longer aboard on a ship or offshore drilling rig L serves its purpose. This could be a producer that is no longer abrasion mechanical wearing or grinding away by friction economic or a water, injection, service, or observation well M abrasion drilling a well-cutting method using abrasive that is no longer in use. abd particles such as sand jetted from nozzles abandonment contour the subsurface elevation contour in abrasion test a laboratory test to determine the abrasive- N a water-drive oil reservoir where the rising oil/water contact ness of drilling fluid weighting additives. The weight loss of reaches the top of the pay and the well is abandoned stainless steel blades run in a mixer with a weighting additive O abandonment costs the cost incurred in plugging a well and sample after a specific time (in mg/min) and number of removing the equipment revolutions per minute are recorded. P abandonment plug a cement bridge used to seal a well abrasive jet cleaning a well-stimulation technique that uses a jetting tool with nozzles on a tubing string. Water, abandonment pressure 1) the minimum gas reservoir pressure necessary to keep a gas well economic as the reser- sometimes carrying sand or acid, is jetted at pressures up to Q 1,000 psi to clean perforations and remove gypsum. voir pressure decreases with gas production. Abandoned pressure often depends on pipeline purchase contract abrasive jetting use of a high-velocity, liquid/abrasive sedi- R pressure, usually between 700 and 1,000 psi. Sometimes ment slurry jet for perforating [See also hydrajet-assisted it is economically possible to compress the gas to pipeline fracturing] pressure. P 2) the minimum reservoir pressure when an oil S a abrasive resistance the ability of a diamond bit to resist or gas well is abandoned scratching abbreviated abstract a set of summaries of all recorded T abrogate 1) to fail to fulfill a contract 2) to repeal a contract instruments concerning the title to a tract of land. This is in by a legislative or authoritative act contrast to a verbatim abstract, which has complete copies of all the recorded instruments. (bob-tail abstract) absolute age dating exact dating of the origin of a rock or U mineral in millions of years ago by radioactive age dating [Cf. ABC method a technique used in refraction seismic to deter- relative age dating] mine the effect of the irregular weathered zone (low-velocity V layer) near the surface. Two seismic shots are made at stations absolute dogleg a well dogleg angle reported that allows for A and C and are recorded at A, B, and C. both horizontal and vertical component deviation. E.g., if a W well changes in deviation from 2° east to 2° west in 100 ft, the AB electrodes electric resistivity logging tool electrodes. absolute dogleg would be 4°/100 ft. The A electrode is current emitting whereas the B electrode is X for current return. absolute filter a filter designed to separate all particles larger than a specific size in microns [Cf. nominal filter] abiogenic gas methane gas formed from an inorganic source [Cf. biogas] absolute humidity amount of water in air measured in terms Y of weight per unit volume, e.g., mg/m3 abiogenic theory or abiotic theory the theory that some hydrocarbons, such as methane, were formed inorganically absolute open flow or open flow potential theoretical rate Z from carbon in the upper mantle and lower crust of the earth a well could flow at the well wall (sandface) with zero atmo- 2 absolute permeability | abstract spheric bottomhole pressure. For a gas well, this is expressed absorber capacity maximum amount of natural gas (in in terms of cubic feet of gas per day. It can be calculated in a standard cubic feet) per day that can be processed by an gas well from a multiple flow test such as a four-point test and absorption tower at a specific absorption rate, temperature, a productivity index plot. (maximum potential flow) AOF, and pressure AOFP absorber tower see absorber absolute permeability a measure of the ease in which a absorptance ratio of absorbed incident energy to total energy single fluid can flow through the pores of a rock when only one fluid is present in the pores (100% saturation). Absolute absorption 1) taking up of one substance by another. permeability is independent of the fluid viscosity. The formula This includes the removal of a liquid by capillary, osmotic, is k = –Q(μ/A) (L/ΔP), where Q is volume flux of fluid, μ is chemical, or solvent reaction in a substance. The extraction a dynamic fluid viscosity, A is cross-sectional sample area, is made by a physical and/or chemical change in a sorbent L is length, and ΔP is the pressure drop across the sample. material. This is used in gas dehydration (glycol dehydra- It is measured in millidarcies. (single-phase permeability tion) with triethylene glycol. Amines are used to chemically or specific permeability) k [Cf. effective permeability and absorb acid gases from natural gas. absp [Cf. adsorption] 2) a relative permeability] decrease in the energy of electromagnetic or acoustic waves as they are converted into another form of energy. Seismic waves absolute porosity ratio of volume of all pore spaces, both passing through rocks are converted into heat energy at a rate interconnected and isolated, to total volume of the rock. It of ~0.25 decibels per cycle. absrn is expressed as a percentage. (total porosity) φ [Cf. effec- a tive porosity] absorption band range of energy wavelengths that a substance absorbs absolute pressure total pressure relative to an ideal vacuum including both atmospheric pressure and gauge pressure. absorption coefficient a measure of the loss of seismic It is often measured in pounds per square inch absolute wave amplitude with distance. It is approximately equal to (psia). P [Cf. gauge pressure] π × ƒ/Q × V, where f is frequency, Q is the quality factor, and V a is velocity. [See also dampening factor and Q] absolute rating diameter of the largest spherical particle in mm that will pass through the filter or screen under absorption factor affinity of a natural gas component to be laboratory conditions [Cf. beta ratio, mean filter rating, and absorbed in absorption oil. It is A = L/KV, where L and V are nominal rating] the respective moles of liquid and vapor from a trap and K is the vapor-liquid equilibrium ratio for the component. Strip- absolute refractive index inverse ratio of the speed of light ping factor is the reciprocal of absorption factor. A through a substance to the speed of light through a vacuum absorption gasoline condensate removed from natural gas absolute temperature temperature based on a scale in which by absorption oil in an absorption tower 0 equals the temperature (–273.15°C) at which molecular motion ceases and there is no heat. On the absolute temper- absorption oil wash oil used in an absorber to separate liquid ature scale, water freezes at 273 kelvin (K) and boils at 373 hydrocarbons from natural gas K. Temperature values in kelvin can be converted to degrees absorption plant a facility used to remove liquid hydrocar- centigrade, or Celsius, by subtracting 273. bons from natural gas in the field. The gas, usually casing- absolute viscosity ratio of shear stress to velocity gradient in head gas, bubbles through oil (absorption oil) that absorbs a fluid. The SI unit of absolute viscosity is the pascal-second the liquid hydrocarbons. The liquid hydrocarbons are then (Pa·s), but the poise (dyne-seconds per square centimeters) removed from the oil by distillation. is more commonly used. (dynamic viscosity and simple absorption refrigeration a cooling system used in a natural viscosity) η [Cf. kinematic viscosity] gas stripping plant where a refrigerant, usually ammonia, is absolute volume volume a solid displaces when placed in absorbed by water [Cf. compression refrigeration] water divided by the weight of the solid absorption spectroscopy an analytical method that measures absolute zero temperature at which there is a complete radiation absorption as a function of wavelength when radia- absence of heat and no molecular movement. Absolute zero is tion (electromagnetic energy) is transmitted through a sample. –273.15°C (–459.688°F), usually rounded off to –460°F. The absorbed wavelengths are used to identify gas composi- tion and quantify the amount. Infrared and ultraviolet-visible absorb see absorption spectroscopy is commonly used. Laser absorption spectros- absorbent material used to remove liquids from a gas by copy is a more advanced analytical method. In flame atomic absorption. Absorption oil is used to remove liquids from absorption, the liquid sample is aspirated, aerosolized, and wet gas. mixed with a combustible gas to be ignited. absorber equipment, typically a tower, designed to use absorption tower see absorber absorption to remove liquids from a gas stream. In an absorp- absorptivity capacity of a substance to absorb incident tion plant, absorber oil is used to remove liquid hydrocarbons radiant energy from natural gas. The gas flows into the bottom of the tower, and the absorption oil enters the top. As the natural gas rises abstract or abstract of title a chronological record of the and bubbles through the descending oil in bubble trays, liquid ownership and all the transfers of ownership of a tract of land hydrocarbons are absorbed from the gas. The liquid hydrocar- based on its legal description from the time the property title bons are then removed from the absorber oil by distillation. A was first recognized by the government to the present. An glycol absorber or TEG unit removes water from natural gas abstract is a set of a) copies (verbatim abstract) or b) summaries in the field. Natural gas sweetening by iron sponge and the (abbreviated or bob-tail abstract) of the chain of all the recorded alkanolamine process are also done in an absorber. Absorbers real property instruments concerning the title to a given tract are designed as either packed or tray-type towers. (absorber of land. It is used in the title examination for a parcel of land tower) absr [See also absorption] and is made by a landman (abstractor) or abstract company to abstract-based title opinion | accuracy 3 establish a clear title to that tract of land. An abstract can be accommodation platform or accommodation rig a ship, A base, complemental, or supplemental. AB, abst semisubmersible (flotel), or fixed platform that houses offshore workers. It is usually adjacent to and connected to a abstract-based title opinion 1) a title opinion that is made from a complete abstract 2) a stand-up title opinion made production platform. (hotel rig) AP B from a run sheet accommodation space vertical space available to deposit sediments. In the ocean, it is from sea level or wave base to the abstract company or abstract plant a commercial firm C bottom of the ocean. that compiles and maintains land ownership records. It contains tract books and card systems recording individuals accordion display a 3-D seismic display consisting of D and the transactions in that county. Other information on narrow, horizontal slices, one above the other file includes probates, court suits, divorces, marriages, and accordion fold see chevron fold bankruptcies. Companies may charge a flat rate or an hourly E rate to let landmen use their facility. accounting rate of return average after-tax net project income divided by the average investment cost over time abstracter or abstractor a professional such as a landman F who makes abstracts, i.e., summaries of interests or legal accounting unit an area or lease considered a single entity ownerships of land and/or mineral rights for production, financial management, and reporting G abstracting service a commercial firm that makes summa- accredited investor as defined under Regulation D of the ries of the interests or legal ownerships of land and/or U.S. Federal Securities Act, an individual who has insti- mineral rights tutional status, an insider position, or a minimum level of H income or net worth ACI abyssal of the ocean environment below 3,000 ft (1,000 m) depth accretion sticking and accumulation of cuttings to a bottom- I hole assembly accelerated cost recovery stem a method used to calcu- late depreciation of equipment for federal tax based on the accrual accounting a method of accounting with the inclu- J rates and lives as defined in federal tax law. The equipment is sion of expenses or revenue that have not been recorded but amortized over a short period. ACRS are applicable to that time period [Cf. cash accounting] K accelerated depreciation a depreciation method that uses accrued royalty royalty payments due on already produced larger amounts of deductions from income in early years and oil or gas declining amounts in later years. Two types are a) declining L accrued treasury asset sum of all discounted cash flows balance and b) sum-of-years. Accelerated depreciation allows until discounted payout ATA for a relatively fast tax write-off. [Cf. straightline depreciation] accumulation chamber equipment used for gas lift when M acceleration of gravity the acceleration due to the gravity of the lack of produced fluid volume makes continuous gas lift the earth. At 45° latitude and sea level, it is 980.615 cm/s2 or impractical. The fluids are allowed to build up in the chamber 32.172 ft/s2 g N until intermittent application of compressed gas forces the accelerator 1) a chemical used to increase reaction rate. A accumulated fluids up the production tube. The standing cement accelerator such as calcium chloride is used to speed valve is closed to protect the formation from the pressure. O up the rate of reaction between cement and water for a more Two types are a) an insert that uses an expanding tubing rapid development of strength and a reduction in setting and section and a dip tube and b) two packers that use the tubing P thickening time. 2) a device that uses an alternating electrical and the casing/tubing annulus. field to accelerate charged particles such as electrons and accumulation efficiency percentage of crude oil and natural protons to high speeds and energies. It can be focused magnet- gas generated in a basin and trapped in commercial reser- Q ically and be continuous or pulsed. Accelerators are used in voirs. It ranges from 36% to 0.3% and averages 10%. logging tools to produce high-energy (14-MeV) neutrons for neutron logging. 3) see jar accelerator accumulation zone see Golden Zone R accelerometer an instrument that senses changes in motion. accumulator 1) a high-pressure cylinder used to store liquid It can be used on a beam-pumping unit to monitor perfor- or gas under pressure for a hydraulic or air-activated system. S mance and to detect parted rods, gas lock, pump off, and Accumulators are used to activate blowout preventers on sanding. They are also used in surveying to measure the accel- drilling rigs. They usually contain hydraulic fluid stored under T eration of a ship or airplane. (dynameter or strain gauge) pressure (3,000 psi) exerted by overlying compressed nitrogen that is separated from the hydraulic fluid by a floating separa- access a means of approach such as a road or easement to a tor (piston) or rubber diaphragm (balloon-type bladder). They U location such as a drillsite are located on the wellhead on a subsea well and on the prime accessory mineral a mineral that occurs in a rock but is not mover skid of a coiled-tubing unit. 2) a tank that temporarily a factor in the classification of that rock. It is often a heavy stores the continuous-process liquid used in a gas plant V mineral that is <1% in abundance. Accessory minerals such as accumulator drill a test run once or more each week on pyrite are most common in sandstones. a drilling rig. The accumulator pumps are shut off, and the W access road a road constructed from a public road to a drill- initial accumulator pressure is recorded. All the preventers site. The route is first surveyed and flagged in coordination are thrown at the same time, and their closing is timed and X with the drilling foreman. recorded. The final accumulator pressure is recorded. The results are reported on the Friday-morning drilling report. accident completion of a task that seemed impossible accuracy the agreement of a measurement with the accepted Y accommodation block living module or quarters deckhouse value of a quantity. It can be quantified as the actual value on an offshore platform. It can contain office space, storage, divided by the measured value as a percent of full scale or catering, and recreational facilities. Z percent of reading on an instrument. [Cf. precision] 4 accuracy denial | acid pickling accuracy denial deliberate signal degradation of a global the steel, reducing the steel’s ductility and causing brittle frac- positioning system used by civilians tures. (hydrogen embrittlement or hydrogen stress cracking) acentric factor a dimensionless number used in data acid-dip survey a method using an acid-bottle inclinometer tables to determine the supercompressibility factor (Z) to to determine well inclination compensate for nonspherical gas molecules. It varies from 0 acid dispersion a solvent-in-acid mixture used to remove oil for a simple molecule to slightly positive for a nonspherical and paraffin from a formation during matrix acidizing. The (acentric) gas molecule. dispersion is a mineral or organic acid and the solvent is an acetic acid a weak organic acid, CHO , used to acidize aromatic. It is also used to remove scale. 2 4 2 wells. Glacial acetic acid is water-free acetic acid. (ethanoic acid effect the increase in chloride ions, pulsed neutron acid) ACEAC, HA c capture count, and porosity calculation due to acidizing a acetylene series unsaturated, open-chain hydrocarbons carbonate reservoir with one triple bond, e.g., acetylene (CH ). They are highly 2 2 acid-extracted gas see sorbed soil gas reactive but not naturally common. The general formula for the acetylene series is C H . (alkyne) acid fracturing or acidfrac a well stimulation technique n 2n – 2 to both dissolve and fracture carbonate reservoirs. An inert, acetylene welding high-temperature burning of acetylene gelled water pad is injected under pressure to fracture the gas and oxygen to join steel formation. An acid-in-oil emulsion is then injected with or acicular a sedimentary particle whose length is at least three without proppants to etch the fracture face. Because the acid times its width acic etches the fracture surfaces unevenly, proppants may not be needed. A regular acid slug can then be injected. The spent acid a chemical compound that, when dissolved in pure water, increases the concentration of free hydrogen ions (H+). fluid is then pumped back out (cleanout), and the well can be swabbed. (fracture acidizing) AF [Cf. matrix acidizing] Acids neutralize bases to form salts, occur below 7 on the pH scale, and turn litmus paper red. The most common acids acid gas a gas that forms an acid with water and is corro- used in acidizing a well are 15% hydrochloric (regular acid), sive. Two common acid gases are H S and CO . They can 2 2 a combination of hydrochloric and hydrofluoric (mud acid), be produced with sour natural gas and removed by sweet- hydrofluoric, acetic, and formic acid. [Cf. base] ening. AG acid additives chemicals and materials added to acid to acidic having the properties of an acid. An acidic solution change the acid properties during acidizing. Some acid has a pH less than 7. [Cf. alkaline] additives are surfactants, sequestering agents, antisludge acid inhibitor an additive used during an acid job to protect agents, corrosion inhibitors, alcohol, gelling agents, fluid loss steel equipment. Acid can attack steel to form iron salts materials, clay stabilizers, scale inhibitors, acid dispersions, and hydrogen gas. Acid inhibitors often form a film coating mutual solvent surfactants, and formation cleaners. that protects the metal equipment. They can be organic, acid bottle the first well surveying tool used. It was a 4-oz containing nitrogen or sulfur, or inorganic, containing copper soda-lime-glass bottle filled half full with hydrofluoric acid or arsenic. Most are acetylenic alcohols such as octynol and and encased in a long cylinder (bomb) or a clinometer case of propargyl. (acid-reaction-rate retarder) ACIN brass or steel. AB acid intensifier an additive used in an acid job to accelerate acid-bottle inclinometer a device used to determine the or intensify the acid reaction. Intensified acid is a mixture of angle (inclination) of a well during an acid-dip survey. A glass inhibited hydrochloric and hydrofluoric acids. The fluoride container of hydrofluoric acid (acid bottle) was run into the intensifies the acid reaction rate. well. The hydrofluoric acid etched the level acid surface on acidity 1) the amount of acid in solution. On the pH scale, the glass. acidic is below 7. [Cf. basicity] 2) see acid number acid job a well stimulation method for carbonate formations. This process is also referred to as acidizing a well and can be either a) a matrix acid job that etches and dissolves the reservoir or b) an acidfrac (fracture acidizing) that both fractures and dissolves the reservoir. The most common acids used are 15% hydrochloric (regular acid), a combination of hydrochloric and hydrofluoric (mud acid), hydrofluoric, acetic, and formic. An acidfrac is a hydraulic fracture job that uses an acidic frac fluid with or without proppants. Hydrofluoric acid can be used to dissolve quartz grains and silica cements. Acidizing was first patented in 1895 by Herman Frasch using hydrochloric acid but did not become effective until 1932, when inhibitors were developed. (acid stimulation or acid treatment) acd, acid, acidg acid number the milligrams of potassium hydroxide neutral- ized by one gram of crude oil or lubricating oil. It is a measure of crude oil acidity and its reactivity with a caustic solution acid-bottle inclinometer with protractor used in enhanced oil recovery. Values above 0.15 are signifi- cantly high. (acidity number or neutralization number) acid brittleness a form of steel corrosion in which free hydro- acid pickling the use of a hydrochloric or sulfuric acid bath gen ions form a wet metal surface. Some hydrogen ions enter for steel tubulars before galvanizing acid-reaction-rate retarder | acquisition input 5 acid-reaction-rate retarder see acid inhibitor acoustic liquid-level instrument an instrument connected A to the casing annulus valve in a well to determine the liquid acid resistance the resistance of cement to the softening and level. It uses an acoustic echo that is amplified, filtered, and corrosive effects of acids recorded on a strip chart. B acid soak or acid spot a well treatment in which acid, usually acoustic location navigation using underwater sound trans- regular acid composed of 15% hydrochloric acid and water, is mission. In the active system, the searching vessel gives off pumped down the tubing and allowed to stand in the comple- C the sound impulse that is received on an acoustic transponder tion zone. It removes scale, coatings, and sludges and cleans on a seafloor object to be located; the acoustic transponder perforation tunnels. Acid soak is similar to a treatment called then gives off its own answering signal. In the passive system, D acid wash. pingers at specific locations on the seafloor give off (i.e., ping) acid-soluble cement a cement slurry that contains calcium sound impulses that are received on the searching vessel; the E carbonate. It can be dissolved after the cement sets with an passive system is used in dynamic positioning. acid. ASC acoustic log a group of wireline well logs each of which acid stage see spearhead stage records some property of acoustic wave travel either through F rocks adjacent to the wellbore or through casing and cement. acid stick a solid stick of acid, usually chloroacetic or sulfamic acid, used to remove scale A sonic log measures the velocity of a compressional wave G through the rocks. An amplitude log measures the amplitude acid stimulation see acidize a well of the waves passing through the rocks. The character log, acid tank a rubber-lined container used to transport acid to microseismogram log, and signature log record some aspect H wellsites for acid jobs of the acoustic wave train. The cement-bond log measures amplitude to indicate the quality of the casing cement bond. acid test the application of acid to a rock to test for limestone The fracture log measures amplitude to locate fractures in the I or the minerals calcite or aragonite. Carbon dioxide bubbles rocks adjacent to the wellbore. The borehole televiewer uses form when the acid reacts with calcium carbonate. ultrasonic waves to image the wellbore. A noise log measures J acid transport truck a truck designed to transport up to ambient noise to locate gas flowing into the well. ACSL, AL 5,000 gallons of acid to a frac or acid job wellsite. Such a acoustic plenum a sound-proof room K truck has multiple compartments to hold different acids and additives. acoustic position reference system a location system used at sea. Acoustic transmitters on the seafloor emit signals in L acid treatment see acid job AT 20–30 kHz that are received by hydrophones (usually four) acid wash or acid washing a well treatment in which acid, mounted on the hull of a vessel. A shipboard computer usually regular acid composed of 15% hydrochloric acid and accurately locates the vessel in reference to the transmit- M water, is pumped down the tubing and past the completion ters. The vessel’s thrusters can be used to put the vessel on zone several times. It removes scale, coatings, and sludge and station. Three types of acoustic position reference systems are N cleans perforation tunnels. Acid soak or spot is a similar a) ultra- or supershort baseline, b) short baseline, and c) long treatment. baseline. (hydro-acoustic position reference) acknowledgment a statement in which the signer declares acoustic reentry use of acoustic signals to relocate a subsea O acceptance of the instrument terms wellhead acme zone of greatest abundance of a specific fossil or acoustic signature oscilloscope pattern made by a sonic P microfossil cement-bond log with different casing cement bonds AC SIGN Acme gas gravity balance an instrument used to determine acoustic survey an acoustic velocity or sonic log measure- Q natural gas specific gravity in the field. The balance operates ment on the principle that densities of two gases at base pressure acoustic transponder a device used on the seafloor that is R are in an inverse ratio to the pressures that give both gases both a receiver and transmitter of sonic energy. It transmits equal buoyant forces. The Acme senior gas gravity balance only after it receives a specific signal allowing the searching tests large volumes of casinghead gas, whereas the Acme vessel to accurately locate the direction and distance to the S junior gas gravity balance tests smaller volumes. acoustic transponder. It is used to reposition a floater for acoustic sound waves or P-waves reentering a subsea well. T acoustic basement the reflection-free area on a seismic acoustic traveltime the time that it takes sound to travel profile that is usually located below the well-layered sedimen- from one point to another, usually measured in microseconds U tary rock. It is usually igneous or metamorphic rock. per foot acoustic blanking a distorted seismic zone with reflection acoustic velocity log see sonic log AVL, ALC 2 V discontinuities and amplitude loss. It is often due to gas in the acoustic wave an elastic sound or seismic wave sediments. acquired lands U.S. federal lands obtained by purchase, W acoustic borehole televiewer see borehole televiewer condemnation, gift, or exchange [Cf. public domain lands] acoustic cement bond log see cement bond log acquisition costs see lease costs X acoustic enclosure an enclosing structure around machinery acquisition footprint or acquisition input the undesired designed to reduce the noise level [See also sound barrier] contribution of 3-D seismic source and receiver geometry on Y acoustic imager see borehole televiewer seismic data and imaging. It is any amplitude or phase anomaly that closely corresponds to surface acquisition geometry. It is acoustic impedance seismic velocity times density. It is seen as amplitude stripes on time and horizon slices. Z sometimes called hardness. AI, Z