Archie equation petrophysics 6518 words 27 pages introduction archie unleashed is an attempt to put the basic log analysis methodology for computing water saturation into a. Through the sonic log we calculate the porosity of the rock. Petrophysics course progression matrix the course progression matrix below shows how the petrophysics courses in this section are structured within each topic, from basic to specialized. A brief history of petrophysics shell interpreted log data petrophysics archie, g. Presented at the 21st annual co 2 flooding conference december 1011, 2015 midland, texas. The archie equation has been the backbone of petrophysics for more than 70 years. Archies laws cementation exponent m most saturation methods rely on work originally done by gus archie in 194041. The rest of the story gene ballay and nelson suarez. Archies equation from wireline logs, niger delta nigeria. Fluid levels within the reservoir formation water what is it composed of. The prototype equation relating rock porosity to various electrical properties of rock bears his name.
Determination of archies parameters is very important, as determination of recoverable hydrocarbon in a place is the main goal of the formation evaluation process panda et al2016. This model was developed by archie, who proposed a 1. He played the key role in identification of producible horizons at the giant elk city field in oklahoma, an episode which dramatically demonstrated for the first time the role that well log measurements could play in identifying pay zones. Taking the logarithm of both sides of equation 2, we get the following equation. Application of archie equation in carbonate reservoir is not easy. S w can also be estimated using a graphical representation of the archie equation known as.
Carbonate reservoir evaluation petrophysics wiley online. How to calculate rw and m porosity cementation exponent from. Crains petrophysical handbook water saturation archie. With the proposed enhancements, the archie equation is no longer empirical but has a sound basis in scientific theory. It usually works well with clean clastic sandstones and carbonate rocks. Pdf the cementation factor, m, of archies equation has specific. To determine the relationships between rock fabric and petrophysical parameters. Nov 18, 2012 reservoir evaluation is one of the critical tasks of any reservoir exploration and field development plan. A graphical solution to archies equation so that plotting resistivity against porosity both on logarithmic scales will produce linear arrangements of the data. In 1952 archie stated in discussing the petrophysics of limestones, it is necessary to first classify them in a manner to portray as much as possible the essential pore characteristics of a reservoir. The archie equation in his classic paper, archie 1942 proposed two equations that described the resistivity behavior of reservoir rocks, based on his measurements on core data. An uncertainty analysis was done for each technique and the relevant impact on the water saturation values was analyzed using archies equation. Pdf the cementation factor, m, of archies equation has specific effects on electric conduction processes in porous media.
Carbonates also have been studied and yielded a recommendation to use m 1. Petrophysics petro is latin for rock and physics is the study of nature is the study of the physical and chemical properties that describe the occurrence and behavior of rocks, soils and fluids. The equations, which are known as the archie equations, relate the resistivity of a formation to the resistivity of the fluids saturating a formation, the porosity of the formation and the. The quality of the water saturation values derived from the archie. Thus, the waxmansmits equationmodel is a semiempirical model. In petrophysics, archies law relates the insitu electrical conductivity of a sedimentary rock to its porosity and brine saturation. Water saturation from electric logs outline what is water saturation and why do we care. Shale volume vsh shale resistivity rsh shale porosity fsh how can these be determined. R w formation water resistivity at formation temperature. In so doing it was essential to have sufficiently clean conditions for there to be a well defined relationship between porosity and cwco. Reservoir evaluation is one of the critical tasks of any reservoir exploration and field development plan.
R w 1r t v sh s wr sh shaly sand equations using effective porosity. S w can also be estimated using a graphical representation of the archie equation known as the pickett plot. Five day carbonate petrophysics gus archie introduced the world to the term petrophysics in 1950. Resistivity logging rt ro, waterleg rt ro, hydrocarbons archie s equations and using then to calculate water saturation when doesnt archie work. Laid the foundation for modern well log interpretation pickett plot a. Swa water saturation from archie method fractional comments. In so doing it was essential to have sufficiently clean conditions for there to be a. Archies laws have since been extended to include shaly sands and carbonates with electrical properties that vary with pore geometry.
The archie equation may not apply at low sw values. It should be related to petrology much as geophysics is related to geology. Water saturation s w can be measured directly from a sealed core, which is an expensive method, or it can be calculated from the archie equation, which is less expensive. In petrophysical logging of electrical rock properties there are two main types. This equation is not shale corrected, so it should not be used in shaly zones. Application of archie equation in carbonate reservoir is not easy due to. Although the origins of the archie equation are empirical, bussian 1982. The m exponent in carbonate petrophysics r e gene ballay, phd.
Sensitivity analysis of the parameters in archies water saturation equation. Tables 5 and 6 contain the solution of three regression equations, which give archie s parameters for the sandstone and carbonate samples. The archie equation was the first empirical model built 1942 to estimate the water saturation in non conductive matrix rocks. Petrophysicists evaluate the reservoir rock properties by employing well. Essay about archie equation petrophysics 6528 words. For a shale layer, r t in equation 3 will be equal to r sh. In the absence of any regional core values, i would recommend using m n 2. There is need for a term to express the physics of rocks. In a carbonate with intergranular or intercrystalline porosity, water saturation calculated using the archie equation is generally reliable. In an earlier note the m exponent in carbonate petrophysics we discussed the physical meaning and range of values of archies m exponent. The equations on the following pages convert the measurements commonly made in open uncased boreholes into the formation properties of scientific and economic interest to. Uncertainty analysis of archies parameters determination. This fundamental vision was followed by a carbonate classification system in 1952 in which he commented in discussing the petrophysics of limestones, it is.
Estimation of water saturation using a modeled equation and. Archie equation petrophysics 6518 words 27 pages introduction archie unleashed is an attempt to put the basic log analysis methodology for computing water saturation into a readable reference document. Here, denotes the porosity, the electrical conductivity of the fluid saturated rock, represents the electrical conductivity of the brine, is the brine saturation, is the cementation exponent of the rock usually in the range 1. In the original work, archie proposed that m lay between 1. As much pores present in the rock the travel time will be greater and in less porous rock the travel time will be little. Archie developed his famous equation to calculate, from well log parameters, the water saturation s w of the uninvaded zone in a formation next to a borehole. I found myself repeating in my mind after stephen prensky, editor of the log analyst, asked me to write this article commemorating the 50th anniversary of archies paper.
The first equation governs the resistivity of rocks that are completely saturated with formation water. On either side of the petrophysics section, you will see courses in associated disciplines for crosstraining. Pdf the cementation factor of archies equation for. This fundamental vision was followed by a carbonate1950. Archies equation is the water saturation model for the determination of water saturation. Archie used an n of 2 and the usual range is from 1. In the original paper, the samples had water saturation greater than 15%. This relation is also known as the archie ii equation. Archies law laid the foundation for modern well log interpretation as it relates borehole electrical conductivity measurements to hydrocarbon saturations which, for fluid saturated rock, equals 1.
Subsequent work by exxon researchers for several sandstone rocks recommended a 0. The cementation factor of archies equation for shaly sandstone reservoirs article pdf available in journal of petroleum science and engineering 232. Used by petrophysicists and log analysts in manual interpretation to have a quick look evaluation. It was often the practice to estimate porosity from the ratio cwco using a standard version of archie s second equation in conjunction with resistivity logging data from nearby water zones. Crains petrophysical handbook resistivity concepts. Petrophysics is suggested as the term pertaining to the physics of particular rock types, whereas geophysics pertains to the physics of larger rock systems composing the earth.
Determination techniques of archies parameters oxford academic. Pdf the cementation factor of archies equation for shaly. The results of the 3d technique confirm the discrepancies observed in the cape technique and the values are within the expected range for carbonate and sandstone reservoirs. Because the speed of sound wave in different medium is different. Common openhole petrophysics interpretation equations. This fundamental vision was followed by a carbonate classification system in 1952 in which he commented. Toby darling, in well logging and formation evaluation, 2005. That means that in the well logging practice, some assumptions must be made or. Typical parameters for the archie equation for consolidated sandstones are a0. The m exponent in carbonate petrophysics geoneurale. Petrophysics msc course notes resistivity theory dr.
Archies equations free download as powerpoint presentation. Increased conductivity is caused by claywater interaction the red curve is. Copyright 2008, held jointly by the society of petrophysicists and well log. Rearrangement of these four equations give the more usual archie water saturation equation this relationship is illustrated below. Latest cased and open hole wireline technologies for oil, water, and gas saturations lance smith, principal petrophysicist schlumberger midland, tx. The waxmansmits equationmodel is based upon an integrated approach of theoretical considerations, new experiments and the old empirical archies equation. We can use a simple archie 4 to a complex archie up to dual water 5, indonesian, dual porosity, triple porosity equation etc. Water saturation calculated from openhole resistivity measurements is a primary input to hydrocarbon reserves evaluation. Petrophysics across the petroleum industry from a core to a. It was often the practice to estimate porosity from the ratio cwco using a standard version of archies second equation in conjunction with resistivity logging data from nearby water zones. Information theory as a guide to log evaluation without petrophysics paul e. That means that in the well logging practice, some assumptions must be made or the system would be undetermined. Archies law is named after gus archie 19071978 who developed this empirical quantitative relationship between porosity, electrical conductivity, and brine saturation of rocks.
This technique is a mathematical manipulation of archie s formula and considers the equation in the form of three regression equations to get the three unknowns a, m and n. Archie is perhaps best known for his contributions to petrophysics. The archieharo equation enables improved calculations of water saturations, with the concomitant gain in accuracy to estimate hydrocarbons in place. R w r t m n which remains the most widely applied equation in petrophysics, in spite of all attempts to replace this empirical relationship with a more rigorous formulation made up of terms identified with distinctive physical properties. The equations, which are known as the archie equations, relate the resistivity of a formation to the resistivity of the fluids saturating a formation, the porosity of the formation and the fractional degree of saturation of each fluid present. Thomas, shell oil company foreword how can you pass up this once in a lifetime opportunity. Archie 2 houston, texas abstract there is need for a term to express the physics of rocks. The equations, which are known as the archie equations, relate the resistivity of.
Analysis and implications of the archieharo equation in. In most quicklook evaluations of clastic reservoirs, it is sufficient to use archie s equation see above to calculate saturations, using the deepest reading resistivity tool directly as r t. Basic petrophysics an intensive 5 day training course this course is designed, developed, and will be delivered under iso quality standards 17 may 2018, dubai. Nov 22, 2011 archie equation archie equation is the most famous equation used by petrophysicists to determine the water saturation in the reservoir in hand.
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