Formation evaluation

A mudlog provides only qualitative information, hence it is unsuitable for an accurate formation evaluation. Mudlogging is therefore nowadays partly replaced by logging while drilling techniques (LWD) which will be covered in Section 5.3. 

Keywords d rec methods, indirect methods, rock properties, coring, core barrel, standard core analysis, special core analysis, slabbed core, sidewall samples, direct indications, microfossils, sonde, logging unit, invasion, mudcake, formation pressure measurement, fluid sampling, measurement while drilling, formation evaluation while drilling. 

The solubility of hydrogen chloride in solutions of aromatic hydrocarbons in toluene and in w-heptane at —78-51 °C has been measured, and equilibrium constants for Tr-complex formation evaluated. Substituent effects follow the pattern outlined above (table 6.2). In contrast to (T-complexes, these 7r-complexes are colourless and non-conducting, and do not take part in hydrogen exchange. 

The drill pipe itself can be used for formation evaluation (Drill Stem Testing— DST), well stimulation (fracturing, acidizing), and fishing operations. 

The various volumes of rock matrix, shale, porosity, overpressure porosity and hydrocarbons are used to compute the various tool responses according to a model. The responses are compared to the measured values and a volume optimization is made to minimize the errors grouped in an incoherence function. The value of the incoherence function for the best fit determines the quality of the answer. Figure 4-335 is an example of formation pressure calculation as well as formation evaluation for lithology and fluid content. 

In all zones the discrepancies between LWD and wireline porosity data are in the range of one to five porosity units. Thus, the LWD neutron data are suitable for formation evaluation. 

Washouts, rugosity, and drillstring wobbling (or vibration) will affect the LWD density readings. However, the LWD density data are generally suitable for formation evaluation. 

In conclusion, the logs available now with LWD are perfectly suitable for a good basic formation evaluation in all types of formations. It should be possible to complete a well successfully with LWD data alone in most instances. 

Jan, Y. H., and Harrel, J. W., MWD directional-focused Gamma Ray—A new tool for formation evaluation and drilling control in horizontal wells, SPWLA 28th Annual Logging Symp., p. A-1-17, 1987. 

NMR has proven to be a valuable tool for formation evaluation by well logging, downhole fluid analysis and laboratory rock characterization. It gives a direct measure of porosity as the response is only from the fluids in the pore space of the rock. The relaxation time distribution correlates with the pore size distribution. This correlation makes it possible to estimate permeability and irreducible water saturation. When more than one fluid is present in the rock, the fluids can be identified based on the difference in the fluid diffusivity in addition to relaxation times. Interpretation of NMR responses has been greatly advanced with the ability to display two distributions simultaneously. 

Exploration Logging, Inc., 1980, Field Geologists Training Guide, An Introduction to Oilfield Geology, Mud Logging and Formation Evaluation, pp. 5-46 to 5-47. 

Roberts, D.D., Lavin, E.H., and Acree, T.E. 1994. Si mulation and analysis of retronasal aroma. In 4th Wartburg Aroma Symposium Aroma Perception, Formation, Evaluation (M. Rothe and H.-P. Kruse,... 

Godbole, S.P., Kamath, V.A., Ehlig-Economides C., SPE Formation Evaluation, 263, March (1988). 

Prensky, Stephen, A Review of Gas Hydrates and Formation Evaluation of Hydrate-Bearing Reservoirs, Society of Professional Well Log Analysts 36th Annual Logging Symposium Transactions, paper GGG, 1995. 

We should like to derive a threshold ratio of for the formation of a local moment. By consideration of Fig. 20-20, you may establish a condition on diC/dn at the cro.ssing (in this case at n = n" = 5/2), which will indicate moment formation. Evaluate the critical (7x/r, Do the parameters of Tables 20-4 and 20-5 fail to predict a local moment as they did for iron with the parameters for Fig. 20-20,a ... 

It follows from the preceding discussion that the equilibrium constant for complex formation evaluated using the rigid rotor-harmonic oscillator approximation, with molecular constants derived from ab initio SCF calculations with a medium basis set (of DZ quality), is not very accurate. Comparison of the AG° values calculated using extended and medium basis sets indicates that the major uncertainty in AG is derived from AH . TASP is not as dependent on the basis set used. Furthermore, it is evident that the entropy term plays an extremely important rote in complex formation neglecting it may result not only in quantitative, but even in qualitative failure. 

H.H., Yuan and B.F., Swanson, 1989. Resolving pore-space characteristics by rate-controlled porosimetry. Society of Petroleum Engineers Formation Evaluation, p. 17-24. 

Zawisza, L., 1986. Hydrodynamic conditions of hydrocarbon accumulation exemplified by the Carboniferous formation in the Lublin Synclinorium, Poland. SPE Formation Evaluation, June 1986, pp. 286-294... 

Pixler, B.O., 1969. Formation evaluation by analysis of hydrocarbon ratios. J. Petroleum Technology, 21 665-670. 

Makurat, A., Gutierrez, M., Knapstad, B., Johnsen, J.H. and Koestler, A. 1995b. Discrete Element Simulation of Faulted Reservoir Behaviour. SPE Formation Evaluation, September. 

A pilot pattern should be chosen so that the injected fluid is well controlled within the pattern. Otherwise, the fluid may be lost through directional flow channels. Then any interpretation or evaluation of the pilot performance would be difficult. When evaluation wells are drilled, cores should be taken in a closed-loop method so that reservoir conditions are maintained. These cores are used to evaluate alkaline consumption, measure relative permeabilities, and so on. Formation evaluation tests are conducted at evaluation wells. Finally, simulation models (sector models) are built to integrate all the data taken to evaluate the alkaline flooding performance. 

Sayegh, S.G., Krause, F.F., Girard, M. DeBree, C. (1990) Rock/fluid interactions of carbonated brines in a sandstone reservoir. Proceedings of the SPE Formation Evaluation meeting, Pembina Cardium, Alberta, Canada, December 1990, pp. 399-405. 

From the EIS data in Fig. 6.20, plotted using the Bode data-presentation format, evaluate Rs, Rp, C, and icorr. Assume Pox = Pred = 100 mV. 

Petersen, M. A. Poll, L. In Aroma Perception, Formation, Evaluation Rothe,... 

Engel, K.H. Albrecht, W. Tressl, R. In Aroma - Perception, Formation, Evaluation Rothe, M. Kruse, H.P., Eds. Deutsches Institut fur Emahrungsforschung Potsdam-Rehbrucke, 1995, pp. 229-246. 

The other trends in values for the various Rs in Table V are consistent with the trends in pairwise interaction contributions to heats of formation evaluated by Allen (19) and discussed by Hine (20). For example, pyronin has a C-C-X pair interaction in place of an O-C-X interaction for pyridine-4-carboxaldehyde for X = OH this difference favors the aldehyde adduct by approximately 7 kcal, although for other Xs, the difference is somewhat smaller. Thus, the values given for the aldehyde are smaller than those for pyronin. We have already pointed out that steric effects are expected in the triarylmethyl derivatives and that the comparison of these with pyronin derivatives are consistent with that expectation (1). 

Smalley, P. C. Hale N. A. 1996. Early identification of reservoir compartmentalization by combining a range of conventional and novel data types. Society of Petroleum Engineers, Formation Evaluation, September 19%, 163-169. 

Smalley, P. C., Goodwin, N. S., Dillon, J. F., Bidinger, C. R. Drozd, R. J. 1996. New tools target oil quality sweetspots in viscous oil accumulations. In Proceedings, Volume W Formation Evaluation and Reservoir Geology. Society of Petroleum Engineers, Annual Technical Conference, Denver, 911-917. 

Gomez-Hemandez, J.J., and Joumel, A.G., 1994, Stochastic Characterization of Gridblock permeabilities, SPE Formation Evaluation, June 94, 93-99. 

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