Identification of igneous reservoir fluid properties based on apparent formation water resistivity P1/2 method -- Taking Carboniferous igneous rocks in CH302, Junggar Basin as an example

Abstract Enhancing hydrocarbon recovery is an ongoing practice in the petroleum industry. Multiple approaches are developed and proved their effectiveness in increasing reservoirs recovery. One of the recent approaches is the Low Salinity Water Injection which is known in the industry by “LoSal”. The determination of the optimum low salinity of the injected water and the mechanism behind its ability to enhance the hydrocarbon recovery are still the subjects of interest for many researchers and industry professionals. Despite the value of the LoSal water injection, it brings with it a considerable challenge to the future formation evaluation, namely the determination of the fluids’ saturation. The mixing of the low salinity injected water with the original high-salinity formation water creates variable water salinity across the reservoir. This is known in the industry by the “mixed-salinity” problem. The horizontal and the vertical heterogeneity of the permeability and porosity across the reservoir is the main factor that controls the “mixed-salinity” distribution in the injected volume. The challenge of calculating the fluids’ saturation exists for both the infill drilling wells and the monitoring wells. For the infill drilling wells, the saturation calculations require accurate formation water resistivity values, Rw, which became variable due to the mixed-salinity. For the monitoring wells, the fluids saturation calculations require accurate formation water sigma absorption, Σw, which also became variable for the same reason. The inability to determine the current Rw and Σw on foot-by-foot basis results in incorrect calculations of the water and hydrocarbon saturations. This creates an economic burden on the reservoir management. The existing methods to interpret the fluids saturation in mixed-salinity reservoirs face the challenges of accuracy, effect of borehole environment and high-data acquisitions cost. A forward modeling is developed to illustrate the problem and its impact on the reservoir decisions making process. A solution to the challenges is proposed, investigated, and proved both theoretically and in the laboratory. The proposed solution is based on lowering the LoSal water resistivity, prior to injection, to be equal to the original formation water resistivity without changing its low salinity. This is achieved by mixing the LoSal water with either acid or alkaline based on the reservoir condition. The acid or alkaline will reduce the resistivity of the LoSal water while keeping its low salinity unchanged. The determination of the required volume of the acid or the alkaline is calculated using the conductivity mixing law and the solution is tested on core plugs. The possible effects of the acid on the formation lithology, specially the clay content is discussed and proved to be negligible due to the very low acid volume required. This is also supported by previously published measurements.

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Using image logs to identify fluid types in tight carbonate reservoirs via apparent formation water resistivity spectrum

Journal of Petroleum Science and Engineering ◽

10.1016/j.petrol.2019.04.006 ◽

2019 ◽

Vol 178 ◽

pp. 937-947 ◽

Cited By ~ 4

Author(s):

Xuqiang Fan ◽

Guiwen Wang ◽

Quanqi Dai ◽

Yafeng Li ◽

Fengsheng Zhang ◽

...

Keyword(s):

Carbonate Reservoirs ◽

Formation Water ◽

Tight Carbonate ◽

Formation Water Resistivity ◽

Water Resistivity

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Calibrated Formation Water Resistivity Sensor

10.4043/30841-ms ◽

2020 ◽

Author(s):

Thomas Pfeiffer ◽

Mahmut Sarili ◽

Cong Wang ◽

Koichi Naito ◽

Yoko Morikami ◽

...

Keyword(s):

Formation Water ◽

Formation Water Resistivity ◽

Water Resistivity

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Determination of Formation Water Resistivity Using Shale Properties

10.2118/15030-ms ◽

1986 ◽

Cited By ~ 2

Author(s):

R.A. Dusenbery ◽

J.S. Osoba

Keyword(s):

Formation Water ◽

Formation Water Resistivity ◽

Water Resistivity

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EVALUATION THE CALCULATION OF WATERSATURATION WITH SIMANDOUX AND INDONESIA METHOD IN THE P LAYER R FIELD

PETRO ◽

10.25105/petro.v8i4.6205 ◽

2020 ◽

Vol 8 (4) ◽

pp. 142

Author(s):

Puri Wijayanti ◽

Ratnayu Sitaresmi ◽

Guntur Herlambang Wijanarko

Keyword(s):

Water Saturation ◽

Effective Porosity ◽

Log Analysis ◽

Formation Water ◽

Porosity Formation ◽

Shale Volume ◽

A Value ◽

Average Water ◽

Formation Water Resistivity ◽

Water Resistivity

Logging Interpretation aims to determine petrophysical parameters such as volume shale, porosity, formation water resistivity used to calculate water saturation values. In this study the wells analyzed were four exploration wells. Log analysis carried out in this well is in the form of qualitative analysis and quantitative analysis. The average shale volume in KML-1, KML-2, KML-3 and KML-4 wells is respectively 0.172, 0.132, 0.167 and 0.115. The average effective porosity of KML-1, KML-2, KML-3 and KML-4 wells is 0.236, 0.268, 0.219 and 0.225 respectively. The values of a, m and n follow the lithology of the well, namely limestone (carbonate) with a value of 1, 2 and 2. The value of Rw is obtained from the Pickett Plot Method that is equal to 1.52 Ωm on KML-1, 1.52 Ωm on KML-2, 1 , 52 Ωm on KML-3 and 0.5 Ωm on KML-4. The average water saturation with the Simandoux Method in KML-1, KML-2, KML-3 and KML-4 wells is 0.336, 0.434, 0.670 and 0.397. While the average water saturation value with the Indonesian Method in KML-1, KML-2, KML-3 and KML-4 wells is 0.439, 0.488, 0.723 and 0.440 respectively. From the comparison with S<sub>w</sub> Core, the Simandoux method is better used in calculating water saturation because the result is closer to the value of Sw Core.

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A non-Archie water saturation method for conventional reservoirs based on generalization of Passey TOC model for unconventional reservoirs

Journal of Petroleum Exploration and Production Technology ◽

10.1007/s13202-020-00945-x ◽

2020 ◽

Vol 10 (8) ◽

pp. 3295-3308

Author(s):

Moustafa Oraby

Keyword(s):

Electrical Properties ◽

Prior Knowledge ◽

Oil Recovery ◽

Water Saturation ◽

Continuous Process ◽

Unconventional Reservoirs ◽

Formation Water ◽

Open Hole ◽

Formation Water Resistivity ◽

Water Resistivity

Abstract The determination of the formation water saturation, Sw, is a continuous process throughout the life of the fields. Multiple water saturation models are developed to increase the accuracy of calculating this critical parameter for both open-hole and cased-hole wells. All current open-hole water saturation models require prior knowledge of some field parameters namely; formation water resistivity, Rw, clay volume, Vc and rock electrical properties (m, n). It is normally assumed that those reservoir parameters as either constant for the entire reservoir section or change by zones. This is obviously an impractical assumption especially for the (m) and (n) parameters. Also, when a reservoir is under water injection for enhanced oil recovery, the water salinity may change throughout the reservoir, based on the distribution of the reservoir permeability and the salinity of the injected water, resulting in a variable Rw. This case represents a real challenge to the existing water saturation models. In this paper, a methodology to determine water saturation without the need for prior knowledge of the formation water resistivity or the rock electrical properties is developed. This approach is a generalization of the Passey total organic carbon, TOC, model which is developed to determine the organic richness of the unconventional reservoirs. The scientific basis of the method, the modification required to be applied in conventional reservoirs, the proof of concept using forward modeled cases and actual field applications in sandstone and carbonate reservoirs are performed to examine the theoretical and the practical applications of the methodology. Excellent results are obtained and discussed.

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