Characteristics of resistivity log response of oil layers under polymer flooding

Resistivity log responses are different when the oil layers is filled by a polymer solution or water and it seriously affects the log interpretation of the water flooded layer. In this paper, we first analyze the electrical properties of the polymer solution. Then, according to the different processes for polymer flooding the reservoir, we perform rock resistivity experiments and analyze the rock resistivity variations in different displacement phases. We also compare the resistivity log responses of oil layers filled with the polymer solution to those filled with water. The results show that when displacing the oil-bearing core by different polymers, the resistivity changes monotonously decrease and show either ＂W＂ type or ＂S＂ type. The resistivity log responses are weak when displacing water and there is no flooded show if the oil layer is injected by a fresh water polymer solution. If the oil layer is injected by a sewage polymer solution, the resistivity log response has similar characteristic as a polluted water flooded layer.

Logging evaluation of deep multi-type unconventional gas reservoirs in the Songliao basin,northeast China:Implications from continental scientific drilling

Multi-type unconventional gas-bearing reservoirs with different lithologies and gas accumulation potential occur in the deep part of the Songliao basin.However,the reservoirs are non-homogeneous,the gas components differ substantially,and not all types of gas-bearing reservoirs have been identified or evaluated.The International Continental Scientific Drilling Program(ICDP)is used as an example to conduct qualitative and quantitative evaluations of deep multi-type unconventional gas-bearing reservoirs using conventional and specialized logging data.The core test data are used to determine the physical properties.The porosity and permeability are compared and analyzed using different methods and models.The results show that the reservoirs have low to ultra-low porosity and ultra-low permeability.Based on the comparison of the rock mechanical parameters and mineral composition,brittleness evaluation parameters are proposed for different types of deep reservoirs in the study region.The mineral brittleness index is highly consistent with the brittleness index based on rock mechanics.An identification method for deep multi-type gas-bearing reservoir and a classification approach for different gas properties are established based on the logging response and parameter interpretation.The methane gas reservoirs have low density(DEN)and low compensated neutron logging(CNL)values and high acoustic(AC)time difference and high resistivity(RT)values.The CO_(2)gas reservoirs have lower RT values and higher CNL values than the hydrocarbon gas reservoirs.The comprehensive analysis of deep gas source rock conditions and of the source-reservoir relationship provides insights for the evaluation of deep multi-type unconventional gas reservoirs.The discovery of high hydrogen content is of significant importance for developing new areas for deep natural gas exploration.

Logging Response Characteristics for Pore Brine Potassium Reservoir in the West of Qaidam Basin

Pore brine potassium and deep sand gravel layer found is of large size and high economic value liquid potash deposit in western Qaidam basin depression tectonic(Fig.1).Because the reservoir is relatively thick,it is difficult to

Well Logging Responses of UHP Metamorphic Rocks from CCSD Main Hole in Sulu Terrane,Eastern Central China

The lithologies of the Chinese Continental Scientific Drilling main hole （CCSD-MH） are mainly comprised of orthogneiss,paragneiss,eclogite,amphibolite,and ultramafic rocks.The statistical results of logs of CCSD-MH indicate that ultramafic rocks are characterized by very high CNL （neutron log） and very low GR （gamma ray log） and RD （resistivity log）;eclogites are characterized by high DEN （density）,VP （P-wave velocity） and PE （photoelectric absorption capture cross section）;orthogneiss and paragneiss are characterized by high GR,U （uranium content）,Th （thorium content）,K （potassium content） and RD,and low DEN,PE,and CNL;logging values of amphibolite are between the logging values of eclogites and paragneiss.In addition,the logs could reflect the degree of retrograde metamorphism of eclogites.The upper section （100-2 000 m） shows higher DEN,PE,VP,and lower GR,U,Th,K,RD than the lower section （2 000-5 000 m）.Most logs of the upper section are more fluctuant than those of the lower section.This indicates that the upper section has more heterogeneities than the lower section.The cross plots of logs indicate that DEN,GR,K,and CNL are more powerful in identifying ultrahigh pressure metamorphic （UHPM） rocks at the CCSD-MH.GR value of the rocks from CCSD-MH shows obviously an increasing trend from ultramafic rock （the most mafic rocks at CCSD-MH） to orthogneiss （the most acid rocks at CCSD-MH）.On the contrary,DEN value decreases from the ultramafic rock to the orthogneiss.CNL log is a good indicator of the content of structure water in crystalline rocks.

Sea-level Eustatic Cycles and Potash Formation Event:A Case Study of Triassic Sichuan Basin

Identification of the favorable salt-and potash-forming layer,we still mainly rely on logging interpretation and coring verification.However,we both know that the continuously carbonate platform is cyclical growing.It has recorded valuable information about the phase transition of carbonate rocks,which were synchronized with the relative sea-level cycles.This paper presents a fast and

Alluvial Fan Facies and Their Distribution in the Lower Talang Acar Formation, Northeast Betara Oilfield, Indonesia

This paper studies the alluvial fan facies characteristics and distribution in the Lower Talang Acar Formation in the Northeast Betara Oilfield. The conglomerate sedimentary characteristics and its distribution were studied based on core data, logging interpretation and seismic property analysis. The research indicated that alluvial fan deposits of Bed F in the Lower Talang Akar Formation were characterized by coarse granularity, poor sorting and low quality. Sand-bodies accumulate longitudinally, and inter-layers are poorly developed, extending locally in the transverse orientation. Typical logging response of alluvial fan system is summarized, and conglomerate is characterized by low gamma-ray （GR） intensity, low resistance, high density and low value between DLD and LLD, which reflects poor physical reservoir properties, coarse rocks and relatively high density. Conglomerate is developed mainly in the northeast and middle-south of the studied area. The upper part of bed F is found in a small area in the middle-south, while the lower part of bed F is developed in a relatively large area in the middle-south.

Shale Gas Characterization of Sembar Formation, Khipro Area, Pakistan

This study pertains to the evaluation of shale gas and rock physics properties of this area with respect to its total organic content of Sember Formation, Khiproarea, Pakistan. We use well logs data for this study. The Khipro area is prominent in the Lower Indus Basin for its hydrocarbon (oil and gas) structural traps. In shale gas evaluation, TOC of Sember Formation is estimated. The analysis has been done with the help of the wire line data of the well Bilal North-01. The presence of shale gas in the study area is analyzed with the help of different techniques. Rock physics and petrophysical analysis have been done in order to get the properties of the area related to the shale gas evaluation.