Preparation and Evaluation of Artificial Cores of Unconsolidated Sandstone Considering the Effect of Formation Water
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RESEARCH ARTICLE-PETROLEUM ENGINEERING
Preparation and Evaluation of Artificial Cores of Unconsolidated Sandstone Considering the Effect of Formation Water Guiqin Wang1 · Hongguang Xu2,3 · Liang Wu4 · Yong Yang5 Received: 31 March 2020 / Accepted: 17 September 2020 © King Fahd University of Petroleum & Minerals 2020
Abstract Unconsolidated sandstone has the characteristics of poor cementation, loose structure, and low intensity. It is difficult to obtain representative cores, and coring from reservoirs is expensive. Thus, artificial cores have been widely used in core flooding experiments instead of natural cores. We found that, during the process of making artificial cores, formation water has an important influence on the physical properties of artificial cores; this factor has been neglected in making of artificial cores thus far. This study investigated the influence of formation water on the cementation and pore throats of artificial cores. In this research, river sand with a similar size distribution to the reservoir samples was chosen as the granule of framework. The results show that the addition of a certain amount of formation water better controls the degree of cementation of artificial cores, and the cores do not need to expand the pores and are relatively easy to mould under the same size composition and dosage of cementing agent. This research demonstrates that formation water is a main factor in making artificial cores of unconsolidated sandstone by comparing parameters such as the porosity, permeability, method of cementing, cementation exponent, and seepage characteristics of natural and artificial cores. The cementation, porosity, and permeability of artificial cores with formation water are better, and the cores have high similarity with natural cores. Consequently, the artificial cores can be used in laboratory experiments instead of natural cores. Keywords Formation water · Artificial core · Unconsolidated sand · Pore throat · Cementation exponent
1 Introduction Heavy oil is widely distributed globally as an unconventional oil resource. With the development of a batch of unconsolidated sand heavy oil reservoirs, this type of oil and gas
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Guiqin Wang [email protected] Hongguang Xu [email protected]
1
School of Petroleum and Environmental Engineering, Yanan University, Yan’an, Shanxi, China
2
Petroleum Engineering Technology Research Institute of Shengli Oilfield Company, SINOPEC, Dongying, Shandong, China
3
Working Station for Postdoctoral Scientific Research, Shengli Oil Administration, Dongying, Shandong, China
4
Research Institute of Exploration and Development of Zichang Oil Production Plant, Yan’an, Shanxi, China
5
Fuxian Oil Production Plant of Yanchang Oilfield Co. LTD, Yan’an, Shanxi, China
reservoir plays an important role in oil and gas resources [1, 2]. Unconsolidated sand has the characteristics of poor cementation, loose structure, and poor intensity which result in very few cores meeting the requirements for laboratory experiments under the condition of conventional
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