Sp log interpretation pdf

Well log interpretation training course petroskills wli. As research progresses in computer applications to well log analysis and lithologie interpretation, computer logs and plots should be included in. Clay type program determines clay type by using spectral gamma ray log this program shows how litology is determined with a density neutron log. The spontaneous potential sp log geological log interpretation. How to easily read a well log in 5 minutes or less using these six ko ko rules published on june 26. All these currents can persist without a borehole, but more importantly, can cause anomalies on the sp log, and in some cases rendering it useless. Basic relationships of well log interpretation aapg. The text discusses how different log types measure various. How to easily read a well log in 5 minutes or less using. The ability of a rock to conduct electrical current or.

Spontaneous potential sp sp dipmeter not covered in this document shdt hrdip pressure testing. Seismic interpretation and basin analysis of the longford subbasin 51 5. A theoretical equation is developed describing membrane. It has been the aim of the work to get connate water resistivities to use in quantitative interpretation of the resistivity curves. Pdf basic well log interpretation mbereobong archibong. The log works by measuring small electric potentials measured in millivolts between depths with in the borehole and a grounded electrode at the surface. The analysis presented in this example is available in databricks as part of the databricks guide. Sp sp response created by electric voltages arising from elctrochemical. Introduction spontaneous potential log principle how it works measurement tools log presentation factors effecting sp log response applications 3. Spontaneous potential is one of the earliest logs used and still in. Shale is usually more radioactive than sand or carbonate, gamma ray log can be used to calculate volume of shale in porous reservoirs.

Introduction since 1949, attention has been directed in this laboratory to the interpretation of sp logs. Contact your schlumberger representative for information on the historical log interpretation chartbook. In the not too distant past, the reading of geology from wireline logs was highly interpretive. Wellog will provide answers to your log interpretation questions free of charge. It is a very simple log that requires only an electrode in the borehole. Identify rocks shale volume correlation bed boundaries porosity.

This log utilizes a single moving electrode in the borehole and a reference electrode at the surface, usually located in the mud pit. Type of log sp short normal lateral induct lon laterologs guard electrode microlog gamma ray. The orientation log o log is designed to be a quick quantitative measure of orientational status for use at bedside with rehabilitation inpatients. Henri doll held 70 patents and wrote seminal papers on log interpretation e. Sedimentary facies interpretation of gamma ray gr log as. Mud log is always adding additional benefit during subsurface interpretation using gr log. Dipmeter interpretation vertical dip variation is characteristic of the structure older, simpler. The natural flow of current and the spontaneous potential curve that would be produced under the salinity conditions. Theoretical analysis and principles of interpretation, h. Spontaneous potential sp and gamma ray logs are discussed first, as their primary use is correlation and their primary interpretive target is gross lithology the. Using the dual water model it was shown that the bond water volume. The sp log measures only the potential drop from the sp currents in the borehole fluid, which may not represent the total sp because there are also potential drops in the formation. Browse other questions tagged interpretation intuition. Interpretation of a neutron log and a gamma log indicate water is perched on a clay.

Note that this is the shallowest interval, so the shale is least compacted. Typical sp log sp has poor limestone limestones response spontaneous potential sp drift. The s3 log trend clearly shows a blocky log pattern, with a discrete break from the underlying spiky log trend. Borehole image interpretation at task fronterra we provide topclass borehole image interpretation services, with the aim to extract the maximum value from your wireline logs. The volume of shale expressed as a decimal fraction or percentage is called v shale. This video is considered as an educational video used for nonprofitable purpose for all petroleum and nonpetroleum students in bue the british university in egypt and any other user for. With these rules, you are able to read any logs in no time, and figure out your own reservoir stories. It may not work for freshwater environment, low resistivity pay zones, hot sands, and perhaps in some unconventional. Roberto peveraro roberto peveraro is a petroleum geoscience and engineering consultant with over 38 years experience in the oil industry, including senior technical management positions in formation evaluation, rock physics and borehole geophysics. Wellog is currently sponsoring a web based seminar called a webinar on log interpretation fundamentals. Guide to computer security log management executive summary a log is a record of the events occurring within an organizations systems and networks. So, there you go the six ko ko rules in well log interpretation.

Basic relationships of well log interpretation introduction this chapter provides a general introduction to well logging principles and methods that will be used throughout the book. Log interpretation principlesapplications schlumberger. Spontaneous potential log, commonly called the self potential log or sp log, is a passive measurement taken by oil industry well loggers to characterise rock formation properties. Succeeding chapters 2 through 6 introduce the reader to specific log types.

In log interpretation, hydrocarbon, the rock, and fresh water of the formation. The various openhole services offered by schlumberger are discussed in some detail, together with essential methods of interpretation and basic applications. Lwd image interpretation hef has interpreted hundreds of logging while drilling image logs lwd using gamma ray, density and resistivity images from all over the world. However, because many oil and gas companies use logs acquired years or even decades ago, a second chartbook, historical log interpretation charts, contains these old charts. Journal of petroleum science and engineering 161996 7179 abstract temperature dependence of the electrochemical potential in shaly sands was studied on core samples from 20 to 80c. If the currents could be interrupted by hypothetical insulating plugs see the upper part of fig. Boundary of permeable and non permeable zone is recorded by sp log. Bulk density typical well log responses lithology fluid gamma ray caliper sp density neutron. Log corrections locate mud cake determine salinity. A spontaneous potential sp log is a record of the way in which the electrical. Michel heeremans, ig, uio the sp log a record of direct current dc voltage or potential that develops naturally spontaneous between a moveable electrode in the welland a fixed electrode located at the surface measured in millivolts mv mnemonics. Spontaneous potential is one of the earliest logs used and. Dewan jt 1983 essentials of modern openhole log interpretation. Applied to smeks field, offshore western niger delta olumuyiwa odundun1.

As always, i dont guarantee it to work all the time. The sp e, is now a simple logarithmic function of r r n f j r. The spontaneous potential log sp measures the natural or spontaneous potential. Sp gr interpretation geological time scale posted in a logarithmic log scale. The sp is constant across the permeable bed, dropping sharply to zero in the shales dashed curve. Crains petrophysical handbook spontaneous potential sp. Spontaneous potential sp, also called self potential, is a naturally occurring electric potential difference in the earth, measured by an electrode relative to a fixed reference electrode. The term equivalent is a result of two assumptions in formulating the ssp. Theoretical analysis and principles of interpretation. Sedimentary facies interpretation of gamma ray gr log as basic well logs in central and lower indus basin of pakistan. These estimated quantities are used to evaluate a zone and to determine whether a well completion attempt is warranted. As with most of the wellog website, improvements and additions occur every day. Determining the porosity and true resistivity of a zone is the first step in converting the raw log data into estimated quantities of oil, gas, and water in a formation.

Theoretical analysis and principles of interpretation, doll, 1948, but his very early success was. Chapter ii principles and classification of well logging. Wellog will provide training on logging and log interpretation. Lwd image interpretation hef petrophysical consulting. Calculation of the gamma ray index is the first step needed to determine the volume of shale from gamma ray log. Identify fractures correlation seismic data fluid saturation. The sp log is a record of the naturally occurring potential in the well bore. However, for the simple sonic log that we are interested in, only the first arrival of the pwave is of interest. The spontaneous potential log sp is a record of potentials or voltages that develop at the contacts between shale or clay beds and a sand aquifer, where they are penetrated by a borehole. Schlumberger 1989 defined formation water as the water uncontaminated by drilling mud that saturates the formation rock. Interpret regression coefficient estimates levellevel. The mud filtrate resistivity rmf at formation temperature calculated from step 3, must be corrected to rmfe, for use in the ssp equation.

There are complex tools that make use of both pwaves and swaves, and some that record the full wave train full waveform logs. Note that the sp log is featureless because the borehole salinity is the same as formation salinity. Spontaneous potentials are often measured down boreholes for formation evaluation in the oil and gas industry, and they can also be measured along the earths surface for mineral exploration or groundwater. Borehole image interpretations from task fronterra provide a comprehensive understanding of brittle and ductile deformation in the nearwellbore environment, and can also. These images are used for a host of possible applications. Figure 1 characteristic log shapes for different types of sand bodies set in shale, a funnel shape, coarsening upward. Published in 1991, log interpretation principlesapplications provides a thorough background of log interpretation. Matthew nton1 1 department of geology, university of ibadan, ibadan, nigeria summary this paper presents the interpretation of data from welllogs and core samples obtained from smeks field, offshore western niger delta. As important as this log derived information is, however, it should not be applied without the inclusion.