Rock Rupture as Affected by Fluid Properties
- P.P. Scott Jr. (Stanolind Oil and Gas Co.) | William G. Bearden (Stanolind Oil and Gas Co.) | G.C. Howard (Stanolind Oil and Gas Co.)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- April 1953
- Document Type
- Journal Paper
- 111 - 124
- 1953. Original copyright American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Copyright has expired.
- 5.1.2 Faults and Fracture Characterisation, 3 Production and Well Operations, 1.14 Casing and Cementing, 1.6 Drilling Operations, 4.1.2 Separation and Treating, 1.11 Drilling Fluids and Materials, 4.1.5 Processing Equipment, 2 Well Completion, 1.6.9 Coring, Fishing, 3.2.3 Hydraulic Fracturing Design, Implementation and Optimisation, 2.5.2 Fracturing Materials (Fluids, Proppant), 4.3.4 Scale
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This paper concerns the rupture or breakdown of rock formations as related to drilling, completing, and stimulating production of wells, and comprises data compiled from a study of literature and records of treatment of oil and gas wells, and from tests conducted in bores drilled into rock cores and outcrops of rock. Results of the investigation indicate that the internal pressure to rupture cylinders of rock and to break-down rock formations surrounding a bore in the earth is dependent upon the extent of intrusion of fluids, the position of bedding planes, the ratio of internal to external diameter, the tensile strength of rock, and magnitude of confining pressure, and is independent of the size of bore, degree of fluid saturation, and temperature of rock within practical limits.
It is concluded that the mathematical relationship of pressure in bores and stresses in the surrounding rock must not be limited by the simplifying assumptions of homogeneity, isotropy, and impermeability; that the incidence of lost circulation of drilling fluids to induced fractures may be reduced by preventing intrusion of fluids into the small intrinsic fractures along weak bedding planes; and that the magnitude of the breakdown pressure of wells to be treated may be lowered by removal of mud cake.
The purpose of this paper is to present and discuss the results of tests which may serve to broaden the understanding of the phenomena of rupture or breakdown of rock and thus contribute to the improvement of the techniques for drilling and completing wells, including such operations as preventing lost circulation, stimulating production, and placing cement.
Since the early recognition of the possibility of rupturing rock adjacent to a well by fluid pressure, the distribution and magnitude of stresses around a well and the internal pressure to cause failure have been expressed mathematically by application of the principles defining the elastic and inelastic behavior of thick-walled cylinders of a homogeneous, isotropic, impermeable material. In either the elastic or plastic state, if the conditions of homogeneity, isotropy, and impermeability were the normal characteristics of rock, there would be no reason to question the validity of the above principles when applied to rock.
|File Size||1 MB||Number of Pages||14|