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An evaluation method of rock pore volume compressibility determination using a computed tomography scanned based finite element model

Moosavi Seyed Amin, Goshtasbi Kamran, Kazemzadeh Ezzatollah

Acta Geophysica

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2023

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Vol. 71, no. 1

147--159

EN

This paper has proposed a new perspective of studying internal structure-based tests, the results of which will improve the present experimental methods and enrich our understanding of rock structure-based modeling without any core preparations, with low cost in a short time. Pore volume compressibility (PVC) is an important feature of rock and is related to mechanical and structural behavior of porous rock sample. An accurate evaluation of pore volume compressibility depends on experimental test which is time-consuming and costly. This paper outlines new method for evaluation of PVC of rock cores using a computed tomography (CT) scan-based finite element method (FEM). The verification studies were performed on a series of porous rock cores which were extracted from deep oil reservoirs in Iran. In order to construct a finite element model, a relationship between spatial elastic properties of samples and CT-scanned data images was derived. The samples were scanned by a conic beam computed tomography (CBCT) machine, and the scanned data were converted into a model to simulate PVC tests. The pore volumetric strains were obtained from a linear elastic analysis for each stress and pore pressure step. To validate the finite element analysis (FEA) results, a series of experimental PVC tests were conducted on the pre-scanned samples and PVC curves were extracted. As a result, the predictions calculated from the CT scan-based numerical models have shown a good correlation with the results obtained from laboratory experiments. The results revealed that it is possible to simulate PVC tests using this numerical proposed evaluation method in such a way that the cost and time of the tests were lowered.

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Compressibility of porous rocks: Part II. New relationships

Jalalh A.A.

Acta Geophysica

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2006

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Vol. 54, no. 4

399-412

EN

Pore volume compressibility is one of the physical properties of a reservoir that must be specified in many reservoir-engineering calculations. The main objective of this work is to provide new general formulas for pore volume compressibility versus porosity on the basis of measured compressibilities of some limestone and sandstone rocks in a wide range of porosity values and of varied type; the measurements were performed on Hungarian reservoir rock samples. The obtained laboratory results were compared with the published correlations of consolidated limestone samples as well with values for friable and strongly consolidated sand-stones. The validity of using compressibility data from the literature was investi-gated. The measured data showed poor agreement with the published correlations. The first approach to find better and more accurate rock compressibility corre-lations consisted of combing all the data available from the literature, using the same formula of Horne’s type. However, this attempt did not give satisfying fitting results. In the next step, by using twelve different fitting formulas, and other com-prehensive nonlinear fitting regression programs, new rock compressibility correla-tions for limestone and sandstone rocks, with better goodness of fit, were developed. These new correlations can be generalized and used for most of oil and gas reservoirs. Key words: pore volume

3

Compressibility of Porous Rocks: Part I. Measurements of Hungarian Reservoir Rock Samples

Jalalh A.A.

Acta Geophysica

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2006

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Vol. 54, no. 3

319-332

EN

Pore volume compressibility is one of the physical properties of a reservoir that must be specified in many reservoir-engineering calculations. In the presented research, the effect of compact pressure, temperature and porosity on compressibility was investigated. A total of twentytwo different cores were tested: five lime-stone, one friable sandstone, fourteen medium to hard sandstone, and two very dense sandstone. Core samples were placed in the test cell and subject to compacting pressure up to 10,000 psi. Runs were made at room temperature and at 52°C for limestone samples. Although there were some publications concerning measurement and study of the effect of pressure and temperature on pore volume compressibility of reservoir rocks, nothing has been published about compressibility of Hungarian reservoir rocks, except of the work of Tóth and Bauer (1988). The present study showed pore volume compressibility data for different Hungarian fields. The result of the study at high temperature (52°C) shows that pore compressibility increases with increasing temperature.