Resistivity logging

The resistivity log can also be used to define oil / water or gas / water contacts. Figure 5.53 shows that the fluid contact can be defined as the point at which the resistivity begins to increase in the reservoir interval, inferring the presence of hydrocarbons above that point. 

Figure 5.57 Permeability indications from resistivity logs...

MWD Technology 901. Directional Drilling Parameters 954. Safety Parameters 961. LWD Technology 971. Gamma and Ray Logs 971. Resistivity Logs 974. Neutron-Density Logs 985. 

Four types of resistivity logs are currently run while drilling ... 

Figure 4-276. Comparison of the compensated dual-resistivity log resistivities run while drilling to the invaded and noninvaded resistivities calculated with wireline phasor induction data. The spurt loss is the ratio R /R (Courtesy Anadrill [tt3].)...

Figure 4-294 shows a set of resistivity logs run in a sand-shale sequence of the Gulf Coast. We have one wireline dual induction log, one MWD resistivity log, a wiper-MWD resistivity log and one gamma ray log. 

Figure 4-294. Comparison of compensated dual-resistivity logs run while drilling and in a wiper pass with the wireline induction logs. (Courtesy Anadrill [113]. ...

To meet the challenges posed by horizontal drilling in particular, a system has been developed to make the measurements at or near the bit and transmit them to the mud telemetry section of the MWD bottomhole assembly. The resistivity at the bit tool is similar to the toroidal resistivity tool described in the section titled Resistivity Logs. As shown in Figure 4-297, the Anadrill geosteering package includes below the Power Pack mud motor ... 

Saturation. Resistivity logs are used for saturation estimates. One, two or more resistivity logs with different investigation depths are usually available. The true resistivity of the formation can be estimated. If a water sand has been drilled near the interval of interest, the formation water can be determined by... 

Resistivity. The 2-MHz LWD amplitude and phase-shift resistivity logs match the wireline deep and medium induction very well. Excellent results are obtained when the invasion is not severe (less than 40 in. in diameter) and in formations 20 f2 m or less. 

The focused resistivity log offered by one of the service companies is very sensitive to borehole diameter and can be used only in a qualitative manner in its present form. 

Archie, GE, The Electrical Resistivity Log as an Aid in Determining Some Reservoir Characteristics, Transactions of the American Institute of Mining Engineers 146, 54, 1942. 

Table 6 Performance of equivalent bromine antimicrobial treatments against biofilms in well-controlled laboratory experiments to simulate industrial applications % Removal % Decrease in Fluid Biofilm Disinfection Oxidizing of Biomass Frictional Resistance (Log Reduction in...

The resistivity log was lowered by cable into the borehole, with the drill bit and drill stem removed, thus enabling the recording of the electrical resistivity of the rock layers that the bit had penetrated. The record helped to identify the hydrocarbon content of the reservoir rock (since both oil and gas have different resistivities than does salt water). It was also used to correlate rock horizons between wells, which proved to be an invaluable tool in subsurface mapping. 

FIGURE 7.22a Chloride anomalies and acoustic and resistivity logs for Blake-Bahama Ridge site 994. (Paul et al., 1996. With permission.)... 

Hydrate was inferred by low temperature observations, interstitial-water low chloride values, and velocity and resistivity logs. Most of the indirect indicators were very similar to those in the earlier Sites 994 and 995. Increases in resistivity (by 0.2 2m) and acoustic velocity (by 0.2 km/s) were marked in the hydrate region. In some cases, the temperature (-2.1°C) was less than the ice point due to endothermic hydrate dissociation. 

Similar to Sites 994 and 995, six indicators of hydrate were present (1) large gas exsolution from cores, (2) high methane sediment concentration, (3) BSRs, (4) low interstitial-water chlorinity, (5) low core temperatures (although IR technology was introduced just after this hydrate leg), and (6) P-wave velocity logs and resistivity logs. As in Sites 994 and 995, there was a discrepancy between the indicated base of the inferred hydrate zone (452 mbsf) and the phase-equilibria stability zone (491 to 524 mbsf). 

Archie GE (1942) The electrical resistivity log as an aid in determining some reservoir characteristics. Trans AIME 146 54-62... 

Figure 22 Logarithm of the normalized resistance log(R/R0) versus the absorbed ionizing dose for samples of the organic charge-transfer salt TMTSF-DMTCNQ 1, electron irradiations 2, x-ray irradiations. (Adapted from Ref. 89.)...

Figure 6.1 Schematic response of well logging parameters to normal and overpressure environments. Cg), = shale conductivity (mmho) Rg), = resistivity (Qm), resistivity log ...

Fig. 2.11 Comparison of electrical resistivities (galv.) measured with the small hand-held prohe and determined hy the inductive method (ind.) for the gravity cores PS1635-1 and PS1836-3. (a) Cross plots of hoth data sets. The dashed lines indicate a difference of 15%. (b) Downcore resistivity logs determined hy hoth methods. Modified after Gerland et al. (1993).

Within Doll s domain there is a simple relation between the field, Q hz, or absolute values of conductivity and frequency. For this reason the interpretation of induction logging within Doll s domain is in essence the same as in resistivity logging based on direct currents. 

Fluid contacts (oil-water contacts (OWC), gas-water contacts (GWC) or gasoil contacts (GOC)) are present in virtually all reservoirs. OWCs and GOCs are usually detected through resistivity logging, petroleum-saturated rocks usually being much more resistive than water-filled rocks. Much attention is placed routinely on the identification of contacts, because this affects the estimated volume of oil or gas contained within a field. However, production... 

Bouma, A.H., Sweet, W.E., Chmelik, F.B., and Heubner, G.L. 1971. Shipboard and in-situ electrical resistivity logging of rmconsolidated marine sediments. The 3rd Offshore Technology Conference Preprints, Houston, TX. 

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