Formation evaluation from well logs in laminated shaly sands has often suffered from lack of proper models, and in many cases led to underestimation of. This paper presents a new model for shaly sand formation permeability evaluation within the transition based on the application of the dual water model formation parameters such as. Analysis of shaly sand reservoir rocks in the eastern niger delta basin using geophysical well logs. Petrophysical models and techniques for shalysand formation. Evaluation of laminated shaly sand sequences in ahwaz oil. Pdf advances in coring and core analysis for reservoir. An onshore gas field hereafter called the r fieldreal name not revealed is in the southeast coast of tanzania which includes a tertiary aged shaly sand formation sandshale sequences. Advances in coring and core analysis for reservoir formation evaluation 3 sedimentology the study of processes by which sedimentary rocks are formed, e. This paper deals with the case of shaly sand formation as a low resistivity pay zone. The formation evaluation results can accurately quantify formation attributes, such as clayvolume, clayboundwater, effectiveporosity and water saturation in shaly sands. Electrical properties, petrophysics and formation evaluation. Both low salinity and shaliness reduce the resistivity contrast between oil and water. On the application of simandoux and indonesian shaly sand. Statoil for providing financial support during the entire period of.
Evaluation of the hydrocarbon potential in lowsalinity. Pdf hydrocarbon saturation assessment of thick shaly sand. Formation evaluation using wireline logs is an appropriate means to obtain petrophysical properties for the r field with well rx in the target. A method of shaly sand correction for estimating gas. Basin and covers approximately 10,000 square miles. In logging analysis, shalysand formation evaluation estimates totalporosity. Evaluation of gas hydrate saturation by effective medium theory in shaly sands. This course tackles the important and nontrivial problem of practical formation evaluation in shaly sand provinces.
The 3rd bone spring formation is predominantly shaly sand with intermittently interbedded carbonate layers. Gas while drilling gwd classification in shalysand. Summary formation evaluation from well logs in laminated shaly sands has often suffered from lack of proper. Shaly sand reservoirs impact on porosity and water. The formation was penetrated by an exploration well rx wherein no core was acquired, and there is no layerwise published data of the petrophysical properties of the r field in the existing. For a considerable time, shaly sand formation evaluation could not accurately quantify clay from standard well logs. The sand percentage here is generally less than 30%. The conventional resistivity in a laminated shaly sand formation for the sand resistivity r sd of 20. The shaly sand formation had alternating lowporosity, gasfilled zones and verylowporosity zones. A modified approach for volumetric evaluation of shaly sand. Petrophysical interpretation in shaly sand formation of a.
However, in shaly formation this approach misleads the results by overestimating the water saturation value due to extra conductivity contribution from clays or shales. A new equation is derived that directly relates shaly sand conductivity to the membrane potential. Hari kumar, ongc summary present paper is a relook at the oil industry practices in making use of the simandoux and indonesian shaly. Subject to many uncertain parameters is the accurate determination of formation porosity and fluid saturation in shaly sand, which are all induced by the existence of shale in pay formation. This paper is intended to provide a better understanding of volumetric evaluation in unconventional shaly sand formations. The shaly sand effect formation factor f was not intrinsic rock property, but instead was seen to vary with water salinity due to clay x called extra conductivity the problem. Pdf integrated petrophysical evaluation of a heterogeneous. Analysis of shaly sand reservoir rocks in the eastern niger. The conventional resistivity in a laminated shaly sand formation for the sand resistivity rsd of.
A simplified shalysand model to provide qualitative if not. Thin laminated shalysand would require high resolution imaging tools to quantify. The petrophysical work flow that is presented through the paper can be applied to other mature, complex shaly sand reservoir for formation evaluation. Pdf petrophysical analysis of shaly sand gas reservoir of. Shaly sand formation evaluation using a single membrane. In potential shalegas basins, due to limited data availability, volumetric evaluation of shaly sand formations is a challenging task for researchers, as well as for exploration and production companies, with the use of conventional well logs. Petrophysical evaluation of shaly sand reservoirs in palougefal oilfield, melut basin, south east of sudan rashid a. Each of these can furnish a significantly different reservoir evaluation. To alleviate the problem of overestimating water saturation by archie many shaly sand interpretation models have been developed that accommodate the. For a symmetric distribution, this will equal the p50 value. Evaluation of low resistivity laminated shaly sand reservoirs. Simandoux 1963 developed a model for estimating water saturation in shaly sand formation. The shale and silt fractions have a large influence on values of effective porosity, water saturation and permeability. Of course, the hydrocarbon inplace is obtainable once porosity and water contents are estimated in the formation.
Petrophysical evaluation, shaly sand reservoirs, density neutron logging, palougefal oil. Accuracy of shaly sand formation evaluation saudi aramco. Integrated petrophysical evaluation applied to the. Successful testing in some exploration wells, which flowed gas and condensate from gumai reservoir, opened the opportunity to explore the new play potential in betara complex.
Sharma center for petroleum and geosystems engineering, the university of texas at austin, cpe 2. Shaly sand evaluation is a complex task and a good geological. In any petroleum province in the world where there are sandshale sequences, the geologist, engineer or log analyst confronts toe shaly sand problem. Petrophysical interpretation in shaly sand formation of a gas field in. Toby darling, in well logging and formation evaluation, 2005.
Cation exchange capacity q v is a key parameter in resistivitybased water saturation models of shaly sand reservoirs, and the accuracy of q v calculation is crucial to the prediction of saturations of oil and gas. Modeling of porosity and permeability for hydrocarbon. Shaly sand evaluation is a complex task and a good geological and local knowledge is important. R ar o w m 1 where r o is the formation resistivity of watersaturated sediment, r w. Tool axis perpendicular to the formation in this case measurement axis of the tool is parallel to the formation layers and hence if vertical resolution of the tool is of the extent to include alternations of sand shale layers, the recorded resistivity will be equivalent to the shale. Review of existing shalysand models and introduction of a. Formation evaluation for thin bed shaly sand reservoirs. Examples with an exercise part sandstone reservoir, shaly sand interpretation, complex mineralogy of a carbonate reservoir help to understand the different methods and algorithms. Therefore, shaly sands are heterogeneous producer reservoir. Shaly sand petrophysics training course petroskills aps. Sandor, shell international exploration and production b. This model was modified to include a, n and m constants.
Mar 28, 2019 evaluation of gas hydrate saturation by effective medium theory in shaly sands. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. Vsh rsh from log analysis indonesia eqn formulated for evaluation of. Jan 30, 2007 typically, the formation lithology included minerals which were termed clay or clay minerals. This study presents an integrated petrophysical evaluation for nahr umr reservoir by highlighting a practical trustworthy approach petrophysical model for nahr umr reservoir in subba oil field depending on available data. A novel process and methodology in deterministic formation evaluation is provided. Summary formation evaluation from well logs in laminated shaly. The agbada formation consists of alternating sand and shales representing sediments of the transitional environment comprising the lower delta plain mangrove swamps, floodplain, and marsh and the coastal barrier and fluviomarine realms. Shaly sand formation evaluation from logs of the skrugard well, southwestern barents sea, norway by marco shaban lutome supervisor.
This leads to large uncertainties in the apparent sand resistivity even for. Petrophysical analysis of shaly sand gas reservoir of titas gas field using well logs. In the laminated shaly sand sequences, the shaly part of these layers is more conductive than the sandy part which in turn yields incorrect estimation of the hydrocarbon in laminated shaly sand layers. Subsurface and petrophysical studies of shalysand reservoir. Analysis of shaly sand reservoir rocks in the eastern niger delta basin using geophysical. Laminated shaly sand reservoirs an interpretation model. Text i have yet to find the ideal petrophysics or formation evaluation text book. Therefore, the effects of clay on porosity and resistivity logs were not accurately incorporated in shaly sands formation evaluation.
Yet, no one method predominates within the industry. An integrated formation evaluation approach for maximizing the value of mature shaly sand reservoir a case study from ravva middle miocene reservoir sudipto datta, bernd herold, tim osullivan, kausik saikia and vivek shankar, cairn india limited, kumar praveer, petrofac summary. Multicomponent induction resistivity logs allow differentiation of horizontal and vertical resistivity. Statoil for providing financial support during the entire period of my study in norway and in tanzania. Connectivity equation and shalysand correction for. The central role of qv and formation water salinity in the evaluation of shaly formations the log analyst, julyaugust 1979. Totalporosity is determined using porositylogs, such as density, neutron and sonic logs. Pnge 735 advance formation evaluation course description.
Analysis of shaly sand reservoir rocks in the eastern niger delta. Cation exchange capacity qv estimation in shaly sand. Us7168310b2 accuracy of shaly sand formation evaluation. In lo g interpretation of shaly sand is used matrix densit y of quartz d. The relationship between the resistivity index and the water saturation is also expressed in terms. Worthington p f 1985 the evolution of shaly sand concepts. Artificial neural network ann prediction of porosity and. Fundamentals of formation evaluation training course. The determination of reservoir quality and formation evaluation processes largely. May 20, 2019 the conventional resistivity measurements are generally influenced by the conductive formation. About the course this course tackles the important and nontrivial problem of practical formation evaluation in shaly sand provinces.
The relationship between the resistivity index and the water saturation is also expressed in terms of a single membrane potential measurement. As a means of investigating this unsatisfactory state of affairs, the development of thinking about the shaly sand problem has been mapped up to the present day. The shaly sand effect formation factor f was not intrinsic rock property, but. Overview well log definition and its importance fundamentals of qualitative and quantitative log interpretation formation evaluation with well logs processing and interpretation of well log data conclusion 3. Although openhole logs were run, the operator needed greater insight into the formation and its fluid contents.
Formation evaluation for thin bed shaly sand reservoirs russian. Petrophysical characterization using the considered shaly sand analysis models will enable a better evaluation of the reservoir quality and. Petrophysical evaluation of shaly sand reservoirs in palougefal. Pdf shales in the reservoir causes complications for the. Geological survey scientific investigations report 20065121, 10 p. Hari kumar, ongc summary present paper is a relook at the oil industry practices in making use of the simandoux and indonesian shaly sand resistivity interpretation models for formation evaluation. Formation evaluation and well log correlation swapnil pal imt geological technology indian institute of technology roorkee 2. The presence of clay minerals and shale laminations strongly affects the physical properties of the reservoir rock and induce significant effects on the response of most logging tools. Core data from well tut8 was from the depth 8284 ft to 8373 ft with 90 data points and core data from well tut12 was from the depth 8194 ft to 8378 ft with 179 data points. Pdf analysis of shaly sand reservoir rocks in the eastern niger. The model was a result based on laboratory studies performed on a physical reservoir model composed of artificial sand and clay in the laboratories of the. In this study, a theoretical expression of q v in terms of shaly sand permeability k shalysand, total porosity. This work presents a formation evaluation for two main santonian sequences of an important gas field composed of siliciclastic reservoirs in santos basin, eastern brazilian margin. Compared with the porous clean sand sample, actual shaly sand usually has clays that adhere to or cover on the grains figure 2.
Silt contents will reduce the permeability and increase the water saturation. A modified approach for volumetric evaluation of shaly. On the application of simandoux and indonesian shaly sand resistivity interpretation models in low and high rw regimes k. Petrophysical evaluation of these reservoirs type is needed. Petrophysical evaluation of shaly sand reservoirs in palouge. An integrated formation evaluation approach for maximizing. An integrated formation evaluation approach for maximizing the value. This petroknowledge training course provides the participant with an intensive training on the concepts of the petrophysical interpretation and well logging. Typically, the formation lithology included minerals which were termed clay or clay minerals. Water saturation models for shaly sand reservoirs presence of shale in the formation has been considered as a very disturbing factor and shown severe effects on petrophysical properties due to reduction in effective porosity, total porosity and permeability of the reservoir ruhovets and fertl, 1982. The shaly sand problem is really a question of identifying, from logs, the degree to which the presence of clay degrades reservoir quality, because clay affects both porosity and. Print to pdf email progression map browse sessions in this discipline.
Petrophysical analysis of the 3rd bone spring formation. The new spectroscopy system unique ly provided the operator with a standalone petrophysical volumetric inter. Pdf formation evaluation of x7 field in the niger delta. Petrophysical evaluation of shaly sand reservoirs in. Evaluation of gas hydrate saturation by effective medium. Inclass and homework exercises are based on real problems actually faced, by the instructor. Advanced methods for interpreting well logs, shaly sand analysis, and production logging methods. Advanced formation evaluation in sandstone reservoirs. The evolution of shalysand concepts in reservoir evaluation.
The occurrence of shale in reservoir rocks can result in erroneous values. Tool enables complete casedhole formation evaluation. In logging analysis, shalysand formation evaluation estimates totalporosity, shale and quartz in shalequartz lithologydescription or clay and sand in claysand lithologydescription, effectiveporosity and watersaturation. An integration and evaluation of gas while drilling data initiated with the objective to. Shaly sand formation evaluation from logs of the skrugard. The aim of this research was to build a comprehensive interpretation algorithm to evaluate the shalysand reservoir. Comparing the results of different shalysand evaluation methods is dif. In logging analysis, shaly sand formation evaluation estimates totalporosity, shale and quartz in shalequartz lithologydescription or clay and sand in clay sand lithologydescription, effectiveporosity and watersaturation. Lithology investigation of shaly sand reservoir by using wire line. Subject are the fundamental techniques of well loggingborehole geophysics and the interpretation of measured data formation evaluation. The assigned formation for evaluation was the 3rd bone spring sitting immediately above the wolfcamp and located in the leonardian period.
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