Controls of pore throat radius distribution on permeability

2017 ◽  
Vol 157 ◽  
pp. 941-950 ◽  
Author(s):  
Amir Maher Sayed Lala ◽  
Nahla A.A. El-Sayed
Keyword(s):  
Pore Throat ◽  
Throat Radius

scholarly journals Microscale Pore Throat Differentiation and Its Influence on the Distribution of Movable Fluid in Tight Sandstone Reservoirs

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Fengjuan Dong ◽  
Xuefei Lu ◽  
Yuan Cao ◽  
Xinjiu Rao ◽  
Zeyong Sun
Keyword(s):  
Ordos Basin ◽  
Pore Throat ◽  
Tight Sandstone ◽  
Throat Radius ◽  
Thin Sections ◽  
Small Pore ◽  
Sandstone Reservoir ◽  
Sandstone Reservoirs ◽  
Classification Evaluation ◽  
Better Than

Tight sandstone reservoirs have small pore throat sizes and complex pore structures. Taking the Chang 6 tight sandstone reservoir in the Huaqing area of the Ordos Basin as an example, based on casting thin sections, nuclear magnetic resonance experiments, and modal analysis of pore size distribution characteristics, the Chang 6 tight sandstone reservoir in the study area can be divided into two types: wide bimodal mode reservoirs and asymmetric bimodal mode reservoirs. Based on the information entropy theory, the concept of “the entropy of microscale pore throats” is proposed to characterize the microscale pore throat differentiation of different reservoirs, and its influence on the distribution of movable fluid is discussed. There were significant differences in the entropy of the pore throat radius at different scales, which were mainly shown as follows: the entropy of the pore throat radius of 0.01~0.1 μm, >0.1 μm, and <0.01 μm decreased successively; that is, the complexity of the pore throat structure decreased successively. The correlation between the number of movable fluid occurrences on different scales of pore throats and the entropy of microscale pore throats in different reservoirs is also different, which is mainly shown as follows: in the intervals of >0.1 μm and 0.01~0.1 μm, the positive correlation between the occurrence quantity of movable fluid in the wide bimodal mode reservoir is better than that in the asymmetric bimodal mode reservoir. However, there was a negative correlation between the entropy of the pore throat radius and the number of fluid occurrences in the two types of reservoirs in the pore throat radius of <0.01 μm. Therefore, pore throats of >0.1 μm and 0.01~0.1 μm play a controlling role in studying the complexity of the microscopic pore throat structure and the distribution of movable fluid in the Chang 6 tight sandstone reservoir. The above results deepen the understanding of the pore throat structure of tight sandstone reservoirs and present guiding significance for classification evaluation, quantitative characterization, and efficient development of tight sandstone reservoirs.

Study on pore structure evaluation of shale gas reservoir-Taking the Lower Cambrian Niutitang Formation in the Cenggong Block, Guizhou Province as an example

2020 ◽  
pp. 1-25
Author(s):  
Fuqiang Lai ◽  
Haiyan Mao ◽  
Jianping Bai ◽  
Daijan Gong ◽  
Guotong Zhang ◽  
...  
Keyword(s):  
High Pressure ◽  
Pore Structure ◽  
Structure Parameters ◽  
Pore Throat ◽  
Throat Radius ◽  
Volume Percentage ◽  
Nmr Logging ◽  
Mercury Intrusion ◽  
Niutitang Formation ◽  
Structure Evaluation

The storage and seepage space of shale is mainly composed of pores and fractures, while the microscopic pore structure and fracture distribution are very complicated. The accuracy of calculation of pore structure parameters is related to whether the reservoir evaluation is correct and effective. Taking the Niutitang Formation in the Cengong area of Guizhou as the research object. Firstly, based on the Archie formula, the process of the wellbore mud intrusion is approximated as the process of the laboratory high pressure mercury intrusion, combined with conventional and nuclear magnetic resonance logging data. The formula deduces a new model for the T2 spectrum conversion pseudo-capillary pressure curve. Then the model is calibrated by the high pressure mercury intrusion experimental data, and the pore structure parameters such as reservoir pore size distribution curve and maximum pore throat radius are calculated. The results show that the maximum pore throat radius and total porosity data calculated by NMR logging are relatively reliable, the median radius error is general, and the displacement pressure and median pressure error are relatively large. The pore volume percentage of 1-10 μm is up to 60%, and the micro-cracks are relatively developed, which is beneficial to the fracturing of the reservoir. Therefore, the use of NMR logging data combined with conventional logging can better reflect the pore structure characteristics of reservoirs, which provides a strong support for complex reservoir identification and qualitative prediction of productivity, and has a good application prospect.

The Law of Reservoir Property Change both before and after Water Flooding in Liaohe Oilfield

2015 ◽  
Vol 733 ◽  
pp. 31-34
Author(s):  
Yan Zhang ◽  
Shuang Yu
Keyword(s):  
Physical Properties ◽  
Water Flooding ◽  
Pore Throat ◽  
Reservoir Properties ◽  
Throat Radius ◽  
Liaohe Oilfield ◽  
Before And After ◽  
Mouth Bar ◽  
Oilfield Development ◽  
Distributary Channel

In order to explore the change laws of physical properties and pore throat radius of reservoir both before and after water flooding to guide the oilfield in-depth fluid diversion, the reservoir properties are analyzed on the basis of core data of early exploratory well and inspection well in the middle and later stages of oilfield development. The theory of reservoir geology and development geology is used to study the change laws of reservoir properties both before and after water flooding in May 20th Development Area of Liaohe oilfield. The research result indicates that reservoir physical properties and pore throat radius have changed in the different period and different microfacies types of sand body [1-3].The permeability is changed far outweigh porosity in the physical properties of reservoir. And with the increase of time, the biggest change is the porosity and permeability of distributary channel, the next are margin of channels, mouth bar. The thin layer of channels and distal bar of physical properties have changed lesser or not. The pore throat radius has declined following distributary channel, mouth bar, thin layer of channels and distal bar in the sedimentary microfacies [4-5].The study results are helpful for the establishment of production measures at the later stage of oilfield development.

scholarly journals Fuzzy Logic in Carbonate Reservoir Quality Assessment: A Case Study from Tarim Basin, China

2017 ◽  
Vol 10 (1) ◽  
pp. 195-203
Author(s):  
Weifu Liu
Keyword(s):  
Fuzzy Logic ◽  
Quality Assessment ◽  
Tarim Basin ◽  
Carbonate Reservoir ◽  
Carbonate Reservoirs ◽  
Reservoir Quality ◽  
Pore Throat ◽  
Throat Radius ◽  
Single Well ◽  
Factor Set

Introduction: To address reservoir quality assessment in highly complex and heterogeneous carbonate reservoirs, a methodology utilizing fuzzy logic is developed and presented in this paper. Based on carbonate reservoir characteristics, three parameters reflecting the macroscopic and microscopic of storage abundance, permeability, and median of pore throat radius were selected to establish the factor set and the evaluation criteria. After analysis of core and test data, a membership function is constructed by semi-drop trapezoid method and the weight formula is also determined by reservoir factor sub-index. The developed method then is used to evaluate a carbonate reservoir in the Tarim Basin in China. Based on the result of single well evaluation, the plane classification map of the carbonate reservoir quality is constructed. Results obtained from reservoir quality assessment in the K32 well show that I-level, II-level, and III-level reservoir qualities account for 58%, 37%, 5% of the reservoir, respectively. The results are consistent with the actual production data demonstrating reliability of the proposed method for reservoir quality assessment practices in usually very complex and heterogeneous carbonate reservoirs. Background: Carbonate reservoirs are complex and heterogeneous and this makes their evaluation a difficult task. Objective: To overcome the uncertainties associated with evaluation of complex carbonate reservoirs a reliable method to accurately evaluate carbonate reservoirs is presented. Methods: Fuzzy logic is used to evaluate a carbonate reservoir from Tarim Basin in China. Based on carbonate reservoir characteristics, three parameters reflecting the macroscopic and microscopic of storage abundance, permeability, and median of pore throat radius are selected to establish the factor set and to evaluate the criteria of carbonate reservoir. After the analysis of core and test data, a membership function is reasonably constructed by semi-drop trapezoid method and the weight formula is also determined by reservoir factor sub-index. Results: An effective methodology for the evaluation of reservoir quality in carbonate reservoirs is established by using fuzzy logic. In addition, an example reservoir from China is used to demonstrate the applicability of the developed method. Conclusion: Based on the result of single well evaluation, the plane classification map of the carbonate reservoir is constructed. Favorable zones in the reservoir are also delineated. Evaluation results are consistent with the actual production data of gas and oil which proves that the proposed method is instrumental in reservoir quality assessment.

scholarly journals Pore throat characteristics of tight reservoirs by a combined mercury method: A case study of the member 2 of Xujiahe Formation in Yingshan gasfield, North Sichuan Basin

2021 ◽  
Vol 13 (1) ◽  
pp. 1174-1186
Author(s):  
Youzhi Wang ◽  
Cui Mao ◽  
Qiang Li ◽  
Wei Jin ◽  
Simiao Zhu ◽  
...  
Keyword(s):  
Pore Structure ◽  
Distribution Range ◽  
Contribution Rate ◽  
Pore Throat ◽  
Tight Sandstone ◽  
Throat Radius ◽  
Xujiahe Formation ◽  
Mercury Injection ◽  
Tight Reservoirs ◽  
Sandstone Reservoirs

Abstract The complex pore throat characteristics are significant factors that control the properties of tight sandstone reservoirs. Due to the strong heterogeneity of the pore structure in tight reservoirs, it is difficult to characterize the pore structure by single methods. To determine the pore throat, core, casting thin sections, micrographs from scanning electron microscopy, rate-controlled mercury injection, and high-pressure mercury injection were performed in member 2 of Xujiahe Formation of Yingshan gasfield, Sichuan, China. The pore throat characteristics were quantitatively characterized, and the distribution of pore throat at different scales and its controlling effect on reservoir physical properties were discussed. The results show that there are mainly residual intergranular pores, intergranular dissolved pores, ingranular dissolved pores, intergranular pores, and micro-fractures in the second member of the Xujiahe Formation tight sandstone reservoir. The distribution range of pore throat is 0.018–10 μm, and the radius of pore throat is less than 1 μm. The ranges of pore radius were between 100 and 200 μm, the peak value ranges from 160 to 180 μm, and the pore throat radius ranges from 0.1 to 0.6 μm. With the increase of permeability, the distribution range of throat radius becomes wider, and the single peak throat radius becomes larger, showing the characteristic of right skew. The large throat of the sandy conglomerate reservoir has an obvious control effect on permeability, but little influence on porosity. The contribution rate of nano-sized pore throat to permeability is small, ranging from 3.29 to 34.67%. The contribution rate of porosity was 48.86–94.28%. Therefore, pore throat characteristics are used to select high-quality reservoirs, which can guide oil and gas exploration and development of tight sandstone reservoirs.

Water Saturation Modeling Challenges in Oil-Down-to Wells: An Example from a Multidarcy North Sea Reservoir

2021 ◽  
pp. 1-15
Author(s):  
A. Larsen ◽  
F. Ahmadhadi ◽  
E. Øian
Keyword(s):  
Relative Permeability ◽  
North Sea ◽  
Water Saturation ◽  
Pore Throat ◽  
Throat Radius ◽  
Initial Water ◽  
Transition Zones ◽  
Excess Water ◽  
Height Model ◽  
Perched Aquifers

Summary The initial water saturation in a reservoir is important for both hydrocarbon volume estimation and distribution of multiphase flow properties such as relative permeability. Often, a practical reservoir engineering approach is to relate relative permeability to flow property regions by binning of the initial water saturation. The rationale behind this approach is that initial water saturation is related to both the pore-throat radius distribution and the wettability of the rock, both of which affect relative permeability. However, pore-throat radius and wettability are usually not explicitly included in geomodel property modeling. Therefore, the saturation height model should not only capture an average hydrocarbon pore volume but also reflect the underlying mechanisms from hydrocarbon migration history and its impact on initial water saturation distribution. This work introduces and describes a new term, excess water, for more precise classification of saturation height model scenarios in reservoirs in which multiple mechanisms have interacted and caused a complex water saturation distribution. An example of the presence of transition zones related to drained local perched aquifers (excess water) in oil-down-to (ODT) wells is shown using a limited data set from a North Sea reservoir. The physical basis for drainage and imbibition transition zones connected to both regional and perched aquifers is given. The distribution of initial water saturation in reservoirs containing excess water is demonstrated through numerical modeling of oil migration over millions of years. Highly permeable reservoirs are more likely to have locally trapped water because of lower capillary forces. A static situation occurs in areas where the capillary forces cannot maintain a high enough water saturation for further water drainage. On the other hand, both high- and low-permeability reservoirs may have significant excess water because of ongoing dynamic effects. In both cases, long distances for water to drain laterally to a regional aquifer enhance the possibility for a dynamic excess water situation.

Methods for Determining the Physical Property Cutoffs of the Effective Reservoirs of the Yaoyi Formation in Cha 48 Zone

2013 ◽  
Vol 395-396 ◽  
pp. 230-233
Author(s):  
Qing Guo Zhang ◽  
Lu Lu Sun ◽  
Xi Chen
Keyword(s):  
Decision Making ◽  
Statistical Method ◽  
Physical Property ◽  
Difficult Problem ◽  
Well Testing ◽  
Actual Situation ◽  
Pore Throat ◽  
Throat Radius ◽  
Reservoir Evaluation

The determination of the physical property cutoffs of the effective reservoirs is a major factor that affects the result of the reserve calculation and is a difficult problem in the research of the reservoir evaluation. It is related to the exploration, development and decision-making. This paper used the empirical statistical method, the minimum pore throat radius method, the oil attitude method and the porosity permeability cross plot method to exploratorily strike the physical property cutoffs of the effective reservoirs of Yaoyi Formation in Cha 48 zone. It was based on the actual situation of the data of cores, the well testing and the well logging and combined with the applicability of various methods. The results achieve the attest of the data from the well testing and the producing test and provide the basis for the reservoir calculation.

Sign in / Sign up

Export Citation Format

Share Document