0


Orientation North 120


240 FMI Dynamic Image Resistive


Maximum horizontal stress direction


Borehole breakout


Minimum horizontal stress direction


Induced fracture


Borehole XX92 breakout N45E Conductive 0


360


Bedding True Dip


deg


Drilling-induced fractures S45E


90


An alternative to this procedure was devel- oped using the MDT Modular Formation Dynamics Tester tool on wireline.14


The MDT tool XX93


uses a straddle-packer arrangement to perform openhole microhydraulic-fracturing tests on small intervals. The MDT device injects fl uid into an interval at a constant rate until a fracture is initiated. The fracture propagates perpendicular to the direction of the minimum in-situ stress. Similar to the DataFRAC service, this technique measures pressure responses after fracture initi- ation to determine the minimum principal stress and can be used with other logging tools— for example the DSI Dipole Shear Sonic Imager and FMI tools— to provide a more comprehensive analysis. Microhydraulic-fracturing tests have been used successfully to define the formation stresses prior to performing frac packing and screenless hydraulic fracturing sand-control operations. Stress information, along with other data, is used to build models of the minimum principal stress versus depth. These models are important in both the design and analysis of the


> In-situ stress direction from borehole images. Borehole imaging data provide detailed stress- direction information (right). For example, in a vertical well, borehole breakouts typically are oriented along the minimum horizontal stress direction, while drilling-induced fractures are aligned with the maximum horizontal stress direction (left). Induced fractures frequently are near-vertical because the minimum stress is usually horizontal.


is earthquake focal mechanisms— compression, tension or strike-slip— determined from the seis- mic waves arriving from earthquakes. A small amount of data comes from strain-relaxation and stress-metering techniques. Local stress informa- tion in oil and gas development areas often comes from boreholes and includes sonic log data, borehole breakout patterns, induced-frac- ture directions, and hydraulic-fracturing and microhydraulic-fracturing data.


An important source of earth stress direc- tional data is wireline and logging-while-drilling (LWD) images and measurements.13


Typically,


the largest principal stress is vertical and attributed to the weight of overburden. Sonic, density and pore-pressure data are used to gen- erate a vertical stress profi le. Borehole imaging devices, such as the FMI Fullbore Formation MicroImager, the OBMI Oil-Base MicroImager and the GVR geoVISION resistivity tools, provide orientation of induced fractures and borehole breakouts. The minimum principal-stress direc- tion is perpendicular to these fractures and aligned with the elongation of the borehole caused by breakouts (above).


Accurate determination of stress directions is crucial in the proper deployment of oriented per- forating gun systems. Perforating in the direction of maximum stress makes hydraulic fracturing more effi cient by reducing tortuosity effects dur- ing pumping. For sand prevention, oriented perforating in the direction of maximum stability has produced good results. Oriented perforating can be achieved with wireline, coiled tubing or tubing-conveyed methods in vertical, deviated or horizontal wells. Regardless of the method used, oriented perforating has helped minimize sand production, particularly in the presence of stress anisotropy.


Modeling a reservoir’s tendency to produce


sand also requires knowledge of principal stress magnitudes. To


physically measure the


magnitude of horizontal stress downhole, a hydraulic-fracturing technique called the DataFRAC fracture data determination service is often used on wells requiring hydraulic- fracture stimulation. After hydraulic-fracture initiation, pressure measurements record the fracture-closing pressure, which is related to the minimum in-situ stress acting perpendicular to the fracture.


13. Anderson J, Simpson M, Basinski P, Beaton A, Boyer C, Bulat D, Ray S, Reinheimer D, Schlachter G, Colson L, Olsen T, John Z, Khan R, Low N, Ryan B and Schoderbek D: “ Producing Natural Gas from Coal,” Oil eld Rev iew 15, no. 3 (Autumn 2003): 8– 31.


Inaba M, McCormick D, Mikalsen T, Nishi M, Rasmus J, Rohler H and Tribe I: “ Wellbore Imaging Goes Live,” Oil eld Rev iew 15, no. 1 (Spring 2003): 24– 37.


Almaguer J, Manrique J, Wickramasuriya S, Habbtar A, Ló pez-de-Cá rdenas J, May D, McNally AC and Sulbará n A: “ Orienting Perforations in the Right Direction,” Oil eld Rev iew 14, no. 1 (Spring 2002): 16– 31.


Cheung P, Hayman A, Laronga R, Cook G, Flournoy G, Goetz P, Marshall M, Hansen S, Lamb M, Li B, Larsen M, Orgren M and Redden J: “ A Clear Picture in Oil-Base Muds,” Oil eld Rev iew 13, no. 4 (Winter 2001/2002): 2– 27.


Peterson RE, Warpinski NR, Lorenz JC, Garber M, Wolhart SL and Steiger RP: “ Assessment of the Mounds Drill Cuttings Injection Disposal Domain,” paper SPE 71378, presented at the SPE Annual Technical Conference and Exhibition, New Orleans, Louisiana, USA, September 30– October 3, 2001.


Bargach S, Falconer I, Maeso C, Rasmus J, Bornemann T, Plumb R, Codazzi D, Hoden eld K, Ford G, Hartner J, Grether B and Rohler H: “ Real-Time LWD: Logging for Drilling,” Oil eld Rev iew 12, no. 3 (Autumn 2000): 58– 78.


14. Desroches J and Kurkjian AL: “ Applications of Wireline Stress Measurements,” paper SPE 58086, revised for publication from paper SPE 48960, prepared for presentation at the SPE Annual Technical Conference and Exhibition, New Orleans, Louisiana, USA, September 27– 30, 1998.


15. Desroches and Woods, reference 3.


16. Brie A, Endo T, Hoyle D, Codazzi D, Esmersoy C, Hsu K, Denoo S, Mueller MC, Plona T, Shenoy R and Sinha B:


“ New Directions in Sonic Logging,” Oil eld Rev iew 10, no. 1 (Spring 1998): 40– 55.


17. Ali AHA, Brown T, Delgado R, Lee D, Plumb D, Smirnov N, Marsden R, Prado-Velarde E, Ramsey L, Spooner D, Stone T and Stouffer T: “ Watching Rocks Change— Mechanical Earth Modeling,” Oil eld Rev iew 15, no. 2 (Summer 2003): 22– 39.


14


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