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. Shaly sand evaluation is a complex task and a good geological. Petrophysical analysis of the 3rd bone spring formation. Thin laminated shalysand would require high resolution imaging tools to quantify.
On the application of simandoux and indonesian shaly sand resistivity interpretation models in low and high rw regimes k. Modeling of porosity and permeability for hydrocarbon. Mar 28, 2019 evaluation of gas hydrate saturation by effective medium theory in shaly sands. Gas while drilling gwd classification in shalysand. The relationship between the resistivity index and the water saturation is also expressed in terms of a single membrane potential measurement. The new spectroscopy system unique ly provided the operator with a standalone petrophysical volumetric inter. The sand percentage here is generally less than 30%. The formation evaluation results can accurately quantify formation attributes, such as clayvolume, clayboundwater, effectiveporosity and water saturation in shaly sands. Accuracy of shaly sand formation evaluation saudi aramco. The shale and silt fractions have a large influence on values of effective porosity, water saturation and permeability. 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.
Laminated shaly sand reservoirs an interpretation model. 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. Fundamentals of formation evaluation training course. A new equation is derived that directly relates shaly sand conductivity to the membrane potential. This leads to large uncertainties in the apparent sand resistivity even for. A modified approach for volumetric evaluation of shaly. Pdf integrated petrophysical evaluation of a heterogeneous. The 3rd bone spring formation is predominantly shaly sand with intermittently interbedded carbonate layers. Pdf hydrocarbon saturation assessment of thick shaly sand. Evaluation of gas hydrate saturation by effective medium. Shaly sand reservoirs impact on porosity and water. Summary formation evaluation from well logs in laminated shaly. The shaly sand effect formation factor f was not intrinsic rock property, but. Both low salinity and shaliness reduce the resistivity contrast between oil and water.
Review of existing shalysand models and introduction of a. Petrophysical analysis of shaly sand gas reservoir of titas gas field using well logs. Examples with an exercise part sandstone reservoir, shaly sand interpretation, complex mineralogy of a carbonate reservoir help to understand the different methods and algorithms. Petrophysical evaluation of shaly sand reservoirs in. 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. Petrophysical characterization using the considered shaly sand analysis models will enable a better evaluation of the reservoir quality and. Evaluation of gas hydrate saturation by effective medium theory in shaly sands. 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.
Multicomponent induction resistivity logs allow differentiation of horizontal and vertical resistivity. Petrophysical evaluation of these reservoirs type is needed. The conventional resistivity in a laminated shaly sand formation for the sand resistivity r sd of 20. R ar o w m 1 where r o is the formation resistivity of watersaturated sediment, r w. Petrophysical evaluation, shaly sand reservoirs, density neutron logging, palougefal oil. Tool enables complete casedhole formation evaluation. Petrophysical evaluation of shaly sand reservoirs in palougefal oilfield, melut basin, south east of sudan rashid a.
For a considerable time, shaly sand formation evaluation could not accurately quantify clay from standard well logs. In lo g interpretation of shaly sand is used matrix densit y of quartz d. This course tackles the important and nontrivial problem of practical formation evaluation in shaly sand provinces. Petrophysical models and techniques for shalysand formation. A simplified shalysand model to provide qualitative if not. 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. Formation evaluation for thin bed shaly sand reservoirs. This petroknowledge training course provides the participant with an intensive training on the concepts of the petrophysical interpretation and well logging. A method of shaly sand correction for estimating gas. The clays, when saturated with formation water, may adsorb water and form immobile water film on the surface of sand grains hill et al1956, waxman and smits 1968, clavier et al1984, juhasz 1979.
In logging analysis, shalysand formation evaluation estimates totalporosity. 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. Therefore, the effects of clay on porosity and resistivity logs were not accurately incorporated in shaly sands formation evaluation. Petrophysical interpretation in shaly sand formation of a gas field in.
Pdf advances in coring and core analysis for reservoir. Pdf petrophysical analysis of shaly sand gas reservoir of. 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. Jan 30, 2007 typically, the formation lithology included minerals which were termed clay or clay minerals. However, in shaly formation this approach misleads the results by overestimating the water saturation value due to extra conductivity contribution from clays or shales. When developing oil and gas fields, there are often the reservoirs consisting of alternating thin sedimentary thin layers of various rocks, clays, siltstone and sandstone fig.
Integrated petrophysical evaluation applied to the. 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. Advanced formation evaluation in sandstone reservoirs. Statoil for providing financial support during the entire period of my study in norway and in tanzania. Evaluation of the hydrocarbon potential in lowsalinity. Lithology investigation of shaly sand reservoir by using wire line. Text i have yet to find the ideal petrophysics or formation evaluation text book. 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. Subsurface and petrophysical studies of shalysand reservoir. Shaly sand formation evaluation from logs of the skrugard. The assigned formation for evaluation was the 3rd bone spring sitting immediately above the wolfcamp and located in the leonardian period. Artificial neural network ann prediction of porosity and. Basin and covers approximately 10,000 square miles. Yet, no one method predominates within the industry.
Summary formation evaluation from well logs in laminated shaly sands has often suffered from lack of proper. 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. An integrated formation evaluation approach for maximizing. However, only two sections of two wells from these four had core data available. 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. The evolution of shalysand concepts in reservoir evaluation. Totalporosity is determined using porositylogs, such as density, neutron and sonic logs. Advances in coring and core analysis for reservoir formation evaluation 3 sedimentology the study of processes by which sedimentary rocks are formed, e. An integration and evaluation of gas while drilling data initiated with the objective to. On the application of simandoux and indonesian shaly sand. 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. This paper deals with the case of shaly sand formation as a low resistivity pay zone.
The petrophysical work flow that is presented through the paper can be applied to other mature, complex shaly sand reservoir for formation evaluation. Formation evaluation is consequently based mostly on logs. The central role of qv and formation water salinity in the evaluation of shaly formations the log analyst, julyaugust 1979. Print to pdf email progression map browse sessions in this discipline. Each of these can furnish a significantly different reservoir evaluation. Cation exchange capacity qv estimation in shaly sand. Formation evaluation and well log correlation swapnil pal imt geological technology indian institute of technology roorkee 2.
Vsh rsh from log analysis indonesia eqn formulated for evaluation of. 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. Petrophysical evaluation of shaly sand reservoirs in palougefal. In this study, a theoretical expression of q v in terms of shaly sand permeability k shalysand, total porosity. Analysis of shaly sand reservoir rocks in the eastern niger.
Us7168310b2 accuracy of shaly sand formation evaluation. Pdf shales in the reservoir causes complications for the. 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. About the course this course tackles the important and nontrivial problem of practical formation evaluation in shaly sand provinces. Worthington p f 1985 the evolution of shaly sand concepts in reservoir from pte 461 at university of southern california. Comparing the results of different shalysand evaluation methods is dif. 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.
Pdf formation evaluation of x7 field in the niger delta. 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. Shaly sand evaluation is a complex task and a good geological and local knowledge is important. The occurrence of shale in reservoir rocks can result in erroneous values. The aim of this research was to build a comprehensive interpretation algorithm to evaluate the shalysand reservoir. 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.
Of course, the hydrocarbon inplace is obtainable once porosity and water contents are estimated in the formation. Sandor, shell international exploration and production b. Formation evaluation using wireline logs is an appropriate means to obtain petrophysical properties for the r field with well rx in the target. This model was modified to include a, n and m constants. Inclass and homework exercises are based on real problems actually faced, by the instructor. 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. An integrated formation evaluation approach for maximizing the value. 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 analysis of shaly sand reservoir rocks in the eastern niger. 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. Petrophysical interpretation in shaly sand formation of a. The conventional resistivity in a laminated shaly sand formation for the sand resistivity rsd of. 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. Pnge 735 advance formation evaluation course description.
Analysis of shaly sand reservoir rocks in the eastern niger delta basin using geophysical well logs. In logging analysis, shalysand formation evaluation estimates totalporosity, shale and quartz in shalequartz lithologydescription or clay and sand in claysand lithologydescription, effectiveporosity and watersaturation. Therefore, shaly sands are heterogeneous producer reservoir. For a symmetric distribution, this will equal the p50 value. May 20, 2019 the conventional resistivity measurements are generally influenced by the conductive formation. Electrical properties, petrophysics and formation evaluation. Shaly sand formation evaluation using a single membrane. To alleviate the problem of overestimating water saturation by archie many shaly sand interpretation models have been developed that accommodate the. Shaly sand formation evaluation from logs of the skrugard well, southwestern barents sea, norway by marco shaban lutome supervisor.
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. Compared with the porous clean sand sample, actual shaly sand usually has clays that adhere to or cover on the grains figure 2. The determination of reservoir quality and formation evaluation processes largely. Worthington p f 1985 the evolution of shaly sand concepts. Formation evaluation for thin bed shaly sand reservoirs russian. Analysis of shaly sand reservoir rocks in the eastern niger delta. Petrophysical evaluation of shaly sand reservoirs in palouge. Advanced methods for interpreting well logs, shaly sand analysis, and production logging methods. Typically, the formation lithology included minerals which were termed clay or clay minerals. Statoil for providing financial support during the entire period of. A modified approach for volumetric evaluation of shaly sand.
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. Toby darling, in well logging and formation evaluation, 2005. Subject are the fundamental techniques of well loggingborehole geophysics and the interpretation of measured data formation evaluation. Hari kumar, ongc summary present paper is a relook at the oil industry practices in making use of the simandoux and indonesian shaly. Shaly sand petrophysics training course petroskills aps. Sharma center for petroleum and geosystems engineering, the university of texas at austin, cpe 2.
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. Analysis of shaly sand reservoir rocks in the eastern niger delta basin using geophysical. The shaly sand formation had alternating lowporosity, gasfilled zones and verylowporosity zones. Evaluation of laminated shaly sand sequences in ahwaz oil. A novel process and methodology in deterministic formation evaluation is provided. Silt contents will reduce the permeability and increase the water saturation. Although openhole logs were run, the operator needed greater insight into the formation and its fluid contents. Evaluation of low resistivity laminated shaly sand reservoirs. Simandoux 1963 developed a model for estimating water saturation in shaly sand formation. The relationship between the resistivity index and the water saturation is also expressed in terms. This paper is intended to provide a better understanding of volumetric evaluation in unconventional shaly sand formations. Geological survey scientific investigations report 20065121, 10 p. In any petroleum province in the world where there are sandshale sequences, the geologist, engineer or log analyst confronts toe shaly sand problem. Connectivity equation and shalysand correction for.
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