The Effect of Cementation on the Mechanical Properties of Sandstones
- Ashraf M. Al-Tahini (U. of Oklahoma) | Carl H. Sondergeld (U. of Oklahoma) | Chandra S. Rai (U. of Oklahoma)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Evaluation & Engineering
- Publication Date
- August 2006
- Document Type
- Journal Paper
- 308 - 316
- 2006. Society of Petroleum Engineers
- 5.1 Reservoir Characterisation, 5.2.1 Phase Behavior and PVT Measurements, 2.4.3 Sand/Solids Control, 5.8.8 Gas-condensate reservoirs, 3.2.3 Hydraulic Fracturing Design, Implementation and Optimisation, 4.1.5 Processing Equipment, 1.2.3 Rock properties, 4.6 Natural Gas, 5.6.4 Drillstem/Well Testing, 3 Production and Well Operations, 5.1.5 Geologic Modeling, 1.14 Casing and Cementing, 2.5.1 Fracture design and containment, 4.1.2 Separation and Treating, 3.2.5 Produced Sand / Solids Management and Control, 5.1.4 Petrology, 1.2.2 Geomechanics, 1.6.9 Coring, Fishing
- 2 in the last 30 days
- 1,019 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 10.00|
|SPE Non-Member Price:||USD 30.00|
The variability in mechanical properties measured on sands from the Jauf and Unayzah formations of Saudi Arabia is observed to be dependent upon cementation. Understanding the role of cementation in controlling the mechanical properties can improve the design of hydraulic-fracture treatments and, hence, improve reservoir performance.
Strength measurements from triaxial-testing data and examination of core in thin sections were used to relate the detailed microstructure and cementation to the variation of mechanical properties. Strength and elastic moduli were determined for 65 samples cored from five different wells. Forty-seven samples were analyzed in thin sections and point counted to determine and quantify cementation. Cements in these two formations have variable composition and habits; both affect the mechanical properties and strength. It is not sufficient to know that cements exist; it is also necessary to know where the cement occurs.
Pure quartz overgrowths play a major role in increasing strength, while clay coatings play a minor role. Simple linear correlations were found relating cement concentrations to strength.
The Jauf and Unayzah reservoirs (Ghawar field, Saudi Arabia) are deep sequences of thin sandstones and shales saturated with condensate-rich gas. These reservoir rocks display a wide variation in both permeability and porosity (Fig. 1) (Al-Qahtani and Buhidma 2001). Hydraulic fracturing has been introduced to enhance productivity in the Jauf sandstones within the Ghawar reservoir.
The complex nature of tectonic stresses, geomechanical properties, and geology leads to problems of sand production and wellbore stability in the Unayzah and Jauf formations. Such problems make the development of these reservoirs challenging. The variations of mechanical properties such as Young's modulus (E), Poisson's ratio, (u), and unconfined compressive strength (UCS) have a direct impact on hydraulic-fracture design. The variation of these properties affects fracture propagation and geometry and, consequently, gas production.
|File Size||3 MB||Number of Pages||9|
Al-Qahtani, M.Y. and Buhidma, I.M. 2001.Improved Near-Well ReservoirCharacterization of a Complex Gas Condensate Reservoir in Saudi Arabia byIntegrating Core, Log, Seismic and Extended Well Test Data. Paper SPE 68140presented at the Middle East Oil Show, Bahrain, 17-20 March.
Brace, W.F. and Riley, D.K. 1972. StaticUniaxial Deformation of 15 Rocks to 30 kb. Intl. J. Rock Mech. Min. Sci.9 (2): 271-288.
Bruno, M.S. and Nelson, R.B. 1991. Microstructural Analysisof the Elastic Behavior of Sedimentary Rock. Mechanical Materials12 (2): 95-118.
Crawford, A.M. 1987. A Modified MultipleFailure State Triaxial Testing Method. Paper presented at the 28th U.S.Symposium on Rock Mechanics, Tucson, Arizona, 29 June-1 July.
Galehouse, J.S. 1969. Point Counting.J. of Sedimentary Petrology 39 (2): 812-815.
Kovari, K. and Tisa, A. 1995. MultipleFailure State and Strain Controlled Triaxial Tests. Rock Mech. Min.Sci. 7 (1): 17-33.
Price, N.J. 1963. The Influence ofGeological Factors on the Strength of Coal Measure Rocks. Geol. Mag.100 (5):428-443.
Prikryl, R. 2001. Some MicrostructuralAspects of Strength Variation in Rock. Intl. J. Rock Mech. Min. Sci. 38 (5):671-682.