scholarly journals Pore Structure Characteristics of Tight Carbonate Reservoir in Qingxi Sag, Jiuquan Basin

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 1) ◽  
Author(s):  
Xiangye Kong ◽  
Jianhui Zeng ◽  
Xianfeng Tan ◽  
Xianglu Gao ◽  
Yu Peng ◽  
...  
Keyword(s):  
Pore Structure ◽  
Tube Bundle ◽  
Pore Space ◽  
Carbonate Reservoir ◽  
Reservoir Rock ◽  
Tight Oil ◽  
Type I ◽  
Structure Characteristics ◽  
Small Pore ◽  
Tight Carbonate

Abstract The Xiagou Formation is the main tight oil reservoir in Qingxi Sag of Jiuquan Basin. Given the poor physical properties and other factors restricting tight oil exploitation and production in this area, studies should focus on microscopic pore structure characteristics. In this study, a nano-CT scanner, a SEM, and an NMR were used to study the pore structure characteristics of a tight carbonate reservoir in Qingxi Sag, Jiuquan Basin. The Xiagou Formation reservoir mainly consists of gray argillaceous dolomite and dolomitic mudstone. The pore categories are mainly elliptic, irregular, intergranular, and intragranular and mostly filled with clay and carbonate cement. Pore space is small, the intergranular or organic pores are mostly separated, and pore-throat is weakly connected. The throats mostly develop with lamellar and tube bundle-like characteristics and with poor seepage ability. The pore-throats mostly span from nanometer to micrometer sizes, and pore diameters are mainly concentrated in the range of 0.01–0.1 and 1–10 μm. It is a unimodal pattern mainly composed of micropores, or a bimodal regular allocation dominated by micropores supplemented by macropores. The relationship between micropore (<0.1 μm) and macropore (>1 μm) content allocation and mean pore diameter strongly controls the permeability of reservoir rocks. When macropore content reaches more than 85%, or when pore content totals less than 3%, the permeability of a reservoir remarkably increases. At a higher ratio of the average finest throat sectional area and throat-pore of reservoir rock, the throat radius lies closer to the connecting pore radius, pore and throat connectivity improves, and reservoir seepage ability becomes stronger. Based on reservoir capacity and seepage ability, pore structures of the tight carbonate reservoirs in study area are classified into type I (small-pore–thin-throat), type II (thin-pore–thin-throat), and type III (microporous-microthroat) with rock permeability>0.1 mD, 0.05–0.1 mD, and <0.05 mD, respectively. The type I pore structure reservoir should be regarded as an indicator of tight oil “sweet spots” reservoir in the study area.

Needles in the Pay Stack ADNOC Exploring Tight-Oil Rock, Triples Production In First Pilot

2021 ◽  
Vol 73 (01) ◽  
pp. 20-22
Author(s):  
Trent Jacobs
Keyword(s):  
Carbonate Reservoir ◽  
Reservoir Rock ◽  
Abu Dhabi ◽  
Data Set ◽  
Slowing Down ◽  
Tight Carbonate ◽  
Potential Impact ◽  
Carbonate Formations ◽  
Oil Company ◽  
Term Data

In the midst of an industry downturn last year, the Abu Dhabi National Oil Company (ADNOC) reached a new oil production ceiling of 4 million B/D. The UAE’s largest producer has no intentions of slowing down. By decade’s end, ADNOC expects to have raised its maximum daily output by another million barrels. To cross that milestone, the company has set its sights on mastering the tight, thin, and unconventional formations that dot the UAE’s subsurface landscape. One of the places where such developments are hoped to unfold soon is known as Field Q. Found in southeastern Abu Dhabi, Field Q sits above a tight carbonate reservoir that holds an estimated 600 million bbl of oil. But with a permeability ranging from 1 to 3 millidarcy and poor vertical communication, the reservoir and its barrels have proven difficult to cultivate economically - until recently. ADNOC has published new details of its first onshore pilot of a “fishbone stimulation” that involved using more than a hundred hollow needles to pierce as far as 40 ft into the reservoir rock. The additional drainage netted by the fishbone needles boosted production threefold in the test well, as compared with its traditionally completed neighbors on the same pad. ADNOC ran the pilot in the summer of 2019 and by the end of the year saw enough production data to launch a wider 10-well pilot that remains underway. Based on a longer-term data set from these wells, the company will decide whether to leap into a fieldwide deployment of the niche completions technology. In the meantime, the petrotechnical team in charge of the test projects have issued roundly positive reviews of the fishbone technique in two recently presented technical papers (SPE 202636; SPE 203086) from the Abu Dhabi International Petroleum Exhibition & Conference (ADIPEC). “There is a chance that the fishbone-stimulated wells can avoid the drilling of multiple wells targeting different sublayers in the same zone,” said Rama Rao Rachapudi, listing one of several of the technology’s advantages over other approaches that were considered. The senior petroleum engineer with ADNOC, who is one of several authors of the papers that cover both the drilling and completions aspects of the pilot, shared during ADIPEC that his onshore team found motivation to test the technology after bringing in a batch of dis-mal appraisal wells. The fishbone system, also known as multilateral jetting stimulation technology, has been a specialized application ever since it was introduced just over a decade ago. Underscoring the potential impact of the current round of pilots on the technology’s adoption rate, ADNOC noted there were only around 30 worldwide fishbone deployments prior to this project. Most of those have been in the Middle East’s naturally fractured and layered carbonate formations - just like those of Field Q.

Simultaneous Interpretation of Three-Phase Relative Permeability and Capillary Pressure for a Tight Carbonate Reservoir From Wireline Formation Testing

2019 ◽  
Vol 142 (6) ◽  
Author(s):  
Xiangnan Liu ◽  
Daoyong Yang
Keyword(s):  
Capillary Pressure ◽  
Relative Permeability ◽  
History Matching ◽  
Carbonate Reservoir ◽  
Reservoir Rock ◽  
Fluid Saturation ◽  
Three Phase ◽  
Tight Carbonate ◽  
Wet Condition ◽  
Oil Gas

Abstract In this paper, techniques have been developed to interpret three-phase relative permeability and water–oil capillary pressure simultaneously in a tight carbonate reservoir from numerically simulating wireline formation tester (WFT) measurements. A high-resolution cylindrical near-wellbore model is built based on a set of pressures and flow rates collected by dual packer WFT in a tight carbonate reservoir. The grid quality is validated, the effective thickness of the WFT measurements is examined, and the effectiveness of the techniques is confirmed prior to performing history matching for both the measured pressure drawdown and buildup profiles. Water–oil relative permeability, oil–gas relative permeability, and water–oil capillary pressure are interpreted based on power-law functions and under the assumption of a water-wet reservoir and an oil-wet reservoir, respectively. Subsequently, three-phase relative permeability for the oil phase is determined using the modified Stone II model. Both the relative permeability and the capillary pressure of a water–oil system interpreted under an oil-wet condition match well with the measured relative permeability and capillary pressure of a similar reservoir rock type collected from the literature, while the relative permeability of an oil–gas system and the three-phase relative permeability bear a relatively high uncertainty. Not only is the reservoir determined as oil-wet but also the initial oil saturation is found to impose an impact on the interpreted water relative permeability under an oil-wet condition. Changes in water and oil viscosities and mud filtrate invasion depth affect the range of the movable fluid saturation of the interpreted water–oil relative permeabilities.

scholarly journals Pore Structure Characteristics and Permeability Prediction Model in a Cretaceous Carbonate Reservoir, North Persian Gulf Basin

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Hao Lu ◽  
Hongming Tang ◽  
Meng Wang ◽  
Xin Li ◽  
Liehui Zhang ◽  
...  
Keyword(s):  
Pore Structure ◽  
Oil Recovery ◽  
Prediction Models ◽  
Carbonate Reservoir ◽  
Good Prediction ◽  
Type I ◽  
Permeability Prediction ◽  
Rock Types ◽  
Fluid Saturation ◽  
Pore Types

Due to the diversity of pore types, it is challenging to characterize the Middle East’s Cretaceous carbonate reservoir or accurately predict its petrophysical properties. In this paper, pore structure in the reservoir is first classified using a comprehensive method. Then, based on the identified pore structure types, a new permeability model with high prediction precision is established. The reservoir is dominated by 6 pore types, such as intergrain pores and moldic pores, and 6 rock types. Grainstone, algal packstone, algal wackestone, and foraminifera wackestone are porous rock types, and echinoderm wackestone and mudstone are nonporous rock types. The types of pore structure in the study area can be divided into four types. Type I has midhigh porosity and medium-high permeability due to its large throat, while type II has a fine throat type with midhigh porosity and midpermeability. Due to their isolated pores, the permeability is low in types III and IV, and out of these two, type III has better storage capacity. Movable fluid saturation calculated by the spectral coefficient method and r apex can characterize the boundary between the connected pores and unconnected pores very well in the research area. It is not accurate enough to simply classify the pore structure by permeability and porosity. The combination of porosity, permeability, r apex , flow zone indicator, and the reservoir quality index can effectively distinguish and classify pore structure types in noncoring wells. The characteristics of each pore structure type are consistent with those of the fractal dimension, which thereby proves the effectiveness of the pore structure classification. New permeability prediction models are proposed for different pore structure types, and good prediction results have been obtained. This study is of great significance for enhancing oil recovery.

scholarly journals Characterization and Consecutive Prediction of Pore Structures in Tight Oil Reservoirs

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2705 ◽  
Author(s):  
Zhaohui Xu ◽  
Peiqiang Zhao ◽  
Zhenlin Wang ◽  
Mehdi Ostadhassan ◽  
Zhonghua Pan
Keyword(s):  
Pore Structure ◽  
Capillary Pressure ◽  
New Method ◽  
Tight Oil ◽  
Type I ◽  
Sweet Spot ◽  
Sem Images ◽  
Pore Structures ◽  
Lucaogou Formation ◽  
Two Samples

The Lucaogou Formation in Jimuaser Sag of Junggar Basin, China is a typical tight oil reservoir with upper and lower sweet spots. However, the pore structure of this formation has not been studied thoroughly due to limited core analysis data. In this paper, the pore structures of the Lucaogou Formation were characterized, and a new method applicable to oil-wet rocks was verified and used to consecutively predict pore structures by nuclear magnetic resonance (NMR) logs. To do so, a set of experiments including X-ray diffraction (XRD), mercury intrusion capillary pressure (MICP), scanning electron microscopy (SEM) and NMR measurements were conducted. First, SEM images showed that pore types are mainly intragranular dissolution, intergranular dissolution, micro fractures and clay pores. Then, capillary pressure curves were divided into three types (I, II and III). The pores associated with type I and III are mainly dissolution and clay pores, respectively. Next, the new method was verified by “as received” and water-saturated condition T2 distributions of two samples. Finally, consecutive prediction in fourteen wells demonstrated that the pores of this formation are dominated by nano-scale pores and the pore structure of the lower sweet spot reservoir is more complicated than that in upper sweet spot reservoir.

scholarly journals Diagenesis and its influence on reservoir quality and oil-water relative permeability: A case study in the Yanchang Formation Chang 8 tight sandstone oil reservoir, Ordos Basin, China

2019 ◽  
Vol 11 (1) ◽  
pp. 37-47 ◽  
Author(s):  
Meng Wang ◽  
Zhaomeng Yang ◽  
Changjun Shui ◽  
Zhong Yu ◽  
Zhufeng Wang ◽  
...  
Keyword(s):  
Pore Structure ◽  
Relative Permeability ◽  
Oil Recovery ◽  
Ordos Basin ◽  
Reservoir Quality ◽  
Tight Oil ◽  
Property A ◽  
Tight Sandstone ◽  
Yanchang Formation ◽  
Small Pore

Abstract Different from conventional reservoirs, unconventional tight sand oil reservoirs are characterized by low or ultra-low porosity and permeability, small pore-throat size, complex pore structure and strong heterogeneity. For the continuous exploration and enhancement of oil recovery from tight oil, further analysis of the origins of the different reservoir qualities is required. The Upper Triassic Chang 8 sandstone of the Yanchang Formation from the Maling Oilfield is one of the major tight oil bearing reservoirs in the Ordos Basin. Practical exploration demonstrates that this formation is a typical tight sandstone reservoir. Samples taken from the oil layer were divided into 6 diagenetic facies based on porosity, permeability and the diagenesis characteristics identified through thin section and scanning electron microscopy. To compare pore structure and their seepage property, a high pressure mercury intrusion experiments (HPMI), nuclear magnetic resonance (NMR), andwater-oil relative permeability test were performed on the three main facies developed in reservoir. The reservoir quality and seepage property are largely controlled by diagenesis. Intense compaction leads to a dominant loss of porosity in all sandstones, while different degrees of intensity of carbonate cementation and dissolution promote the differentiation of reservoir quality. The complex pore structure formed after diagenesis determines the seepage characteristics, while cementation of chlorite and illite reduce the effective pore radius, limit fluid mobility, and lead to a serious reduction of reservoir permeability.

Study on Micro Pore Structure Characteristics of Carbonate Cores of Low Permeability

2014 ◽  
Vol 1015 ◽  
pp. 129-134
Author(s):  
Pu Fu Xiao ◽  
Zheng Ming Yang ◽  
Ya Pu Zhang ◽  
Chang Cheng Gai
Keyword(s):  
Pore Structure ◽  
Middle Eastern ◽  
Flow Characteristics ◽  
Carbonate Reservoir ◽  
Oil Field ◽  
Low Permeability ◽  
Structure Characteristics ◽  
Constant Rate ◽  
Carbonate Cores

In order to understand the characteristics and flow characteristics of the low permeability carbonate reservoir of Middle East, in this paper, we take a Middle Eastern oil field as an example, using constant-rate mercury penetration technique, analyzing the micro pore structure characteristics of carbonate cores. The results show that, the pore radius distribution characteristics of different permeability is similar, mostly between 90-200μm, the peak occur at about 120μm. After that, we get the main factor affecting the reservoir physical quality of carbonate reservoir is throat rather than pore. And compared with the same permeability of sandstone cores, found that even if a poor sorting and strong heterogeneity of carbonate cores, but due to its throat contribution to permeability is very balanced, show the low permeability carbonate difficulty of development smaller than sandstone, only reducing the pore throat ratio, improve the ability of reservoir seepage, can have a good development effect.

Characterization of Pore Structure in Tight Oil Reservoir Rock

2015 ◽  
Author(s):  
Leng Zhenpeng ◽  
Lv Weifeng ◽  
Ma Desheng ◽  
Liu Qingjie ◽  
Jia Ninghong ◽  
...  
Keyword(s):  
Pore Structure ◽  
Reservoir Rock ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Tight Oil Reservoir

scholarly journals Full-Scale Pore Structure Characteristics and the Main Controlling Factors of Mesoproterozoic Xiamaling Shale in Zhangjiakou, Hebei, China

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 527
Author(s):  
Liangwei Xu ◽  
Keji Yang ◽  
Hao Wei ◽  
Luofu Liu ◽  
Xiao Li ◽  
...  
Keyword(s):  
Pore Structure ◽  
Mineral Content ◽  
Pore Space ◽  
Controlling Factors ◽  
Full Scale ◽  
Quartz Content ◽  
Structure Characteristics ◽  
Main Controlling Factors ◽  
Accumulation Mechanism ◽  
Analytical Program

Nanoscale pore structure characteristics and their main controlling factors are key elements affecting the gas storage capacity, permeability, and the accumulation mechanism of shale. A multidisciplinary analytical program was applied to quantify the pore structure of all sizes of Xiamaling shale from Zhangjiakou, Hebei. The result implies that Mercury injection porosimetry (MIP) and low-pressure N2 curves of the samples can be divided into three and four types, respectively, reflecting different connectivity performances. The maximum CO2 adsorbing capacity increases with increasing total organic carbon (TOC) content, pore volume (PV), and surface area (SA) of the micropores are distributed in a three-peak type. The full-scale pore structure distribution characteristics reveal the coexistence of multiple peaks with multiple dominant scales and bi-peak forms with mesopores and micropores. The porosity positively correlates with the TOC and quartz content, but negatively correlates with clay mineral content. Organic matter (OM) is the main contributor to micropore and mesopore development. Smectite and illite/smectite (I/S) assist the development of the PV and SA of pores with different size. Illite promotes the development of the nanoscale PV, but is detrimental to the development of the SA. Thermal maturity controls the evolution of pores with different size, and the evolution model for the TOC-normalized PVs of different diameter scales is established. Residual hydrocarbon is mainly accumulated in micropores sized 0.3 to 1.0 nm and mesopores sized 40 nm, 2 nm and less than 10 nm. Since the samples were extracted, the pore space occupied by residual hydrocarbon was released, resulting in a remarkable increase in PV and SA.

Characteristics and origin of the pore structure of the lacustrine tight oil reservoir in the northwestern Jiuquan Basin, China

2019 ◽  
Vol 7 (3) ◽  
pp. T625-T636
Author(s):  
Chunyan Fan ◽  
Xianglu Tang ◽  
Yuanyin Zhang ◽  
Yan Song ◽  
Zhenxue Jiang ◽  
...  
Keyword(s):  
Pore Structure ◽  
Oil Reservoirs ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Type I ◽  
Thin Sections ◽  
Tectonic Events ◽  
Tight Oil Reservoir ◽  
Tight Oil Reservoirs ◽  
Intercrystalline Pores

The pore structure controls the formation processes of tight oil reservoirs. It is meaningful to study the characteristics and origin of the pore structure of the tight oil reservoir. We have analyzed the pore structure of the tight oil reservoir by thin sections, scanning electron microscopy, and mercury intrusion porosimetry. We analyze the origin of the pore structure based on sedimentological, diagenetic, and tectonism processes. The porosity of the tight oil reservoirs is mainly approximately 2%–10%, and the permeability is mainly from 0.01 to 0.3 mD. The pores of the lacustrine tight oil reservoir can be classified into the primary pore and the secondary pore. The main pores are matrix micropores and clay intercrystalline pores, as well as a few dissolved pores. However, the primary residual intergranular pore has almost disappeared, leading to a poor connectivity with a general size between 20 and 50 μm. The pore throat is divided into three categories (type I, type II, and type III) according to the porosity, permeability, and throat size and distribution. We determine that the pore structure of the lacustrine tight oil reservoir is related to sedimentary, diagenetic processes, and later tectonic events. The compaction and cementation are the main factors, whereas the dissolution and tectonic events have minor effects.

scholarly journals Digital Rock Samples Porosity Analysis by OTSU Thresholding Technique Using MATLAB

2020 ◽  
Vol 21 (3) ◽  
pp. 57-66
Author(s):  
Yahya Jirjees Tawfeeq ◽  
Jalal A. Al-Sudani
Keyword(s):  
Image Processing ◽  
Pore Structure ◽  
Thin Section ◽  
Digital Image ◽  
Carbonate Reservoir ◽  
Oil Field ◽  
Reservoir Rock ◽  
Reservoir Rocks ◽  
Rock Samples ◽  
Digital Rock

Porosity plays an essential role in petroleum engineering. It controls fluid storage in aquifers, connectivity of the pore structure control fluid flow through reservoir formations. To quantify the relationships between porosity, storage, transport and rock properties, however, the pore structure must be measured and quantitatively described. Porosity estimation of digital image utilizing image processing essential for the reservoir rock analysis since the sample 2D porosity briefly described. The regular procedure utilizes the binarization process, which uses the pixel value threshold to convert the color and grayscale images to binary images. The idea is to accommodate the blue regions entirely with pores and transform it to white in resulting binary image. This paper presents the possibilities of using image processing for determining digital 2D rock samples porosity in carbonate reservoir rocks. MATLAB code created which automatically segment and determine the digital rock porosity, based on the OTSU's thresholding algorithm. In this work, twenty-two samples of 2D thin section petrographic image reservoir rocks of one Iraqi oil field are studied. The examples of thin section images are processed and digitized, utilizing MATLAB programming. In the present study, we have focused on determining of micro and macroporosity of the digital image. Also, some pore void characteristics, such as area and perimeter, were calculated. Digital 2D image analysis results are compared to laboratory core investigation results to determine the strength and restrictions of the digital image interpretation techniques. Thin microscopic image porosity determined using OTSU technique showed a moderate match with core porosity.

Sign in / Sign up

Export Citation Format

Share Document