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Bit Design Iteration 2 (Bit C) By the time the team was ready for a bit new design iteration, the <strong>Saudi</strong> Arabia operations bit designer used new analytical tools, including the energy balance and transition drilling modules. The cutting structure was optimized using the new tools, which further reduced the force imbalance and obtained minimum energy balance values. It was adjusted to obtain smooth transition drilling, simulating hard rock (35,000 psi compressive strength) and soft rock (10,000 psi compressive strength). Figure 14 shows the ability of the bit to return to an imbalance stage (flat lines) after drilling through a formation change, and Fig. 15 shows its maximum value at the bit nose, which is the right trend. Because the major challenge was to increase the bit life without sacrificing the ROP, Bit C implemented the use of a new PDC cutting element, R1 cutters. The R1 cutters act as a secondary cutting structure to assist cutting after the primary cutting structure begins to show some degree of wear. In addition to the additional diamond volume, the R1 cutters help to prevent impact damage and to control the depth of cut when the cutting structure is still in perfect condition. Figure 16 illustrates the R1 cutter geometry. An additional improvement made to Bit C includes the rearrangement of the bit nozzle after the CFD indentified some interference zones in which the flow coming from the bit was re-circulated around the bit face before it was evacuated through the annulus space. Bit C provided many good runs in all Ghawar zones, completing the directional section in one run in 95% of cases. The bit condition at the end of the run improved substantially, and the bit achieved the optimum ROP while completing the interval. Figure 17 shows the smooth wear at the end of the run and the performance of the R1 cutters after the main cutting structure began to wear. Bit Design Iteration 3 (Bit D) In the last quarter of 2008, two new technological advances made it possible to increase the bit performance standard in the <strong>Saudi</strong> Arabia deep gas drilling operations. The devel - opment of the cutters for extreme drilling conditions, which Fig. 14. The ability of the bit to return to an imbalance stage (flat lines) after drilling through a formation change. Cutter Torque Change 7 6 Percent Torque Change 5 4 3 2 1 0 0 10 20 30 40 50 Cutter Number Fig. 15. The maximum value at the bit nose. Fig. 16. R1 cutter implemented on Bit C. 52 SUMMER 2010 SAUDI ARAMCO JOURNAL OF TECHNOLOGY
laboratory and previous field tests showed to be more abrasive and impact resistant, brought new possibilities to the bit design scenario. The availability of a stronger PDC cutter enabled a lighter set bit to be used in this application and increased the ROP. The introduction of the DxD simulator enabled the quantification and optimization of all bit features for an optimum product capable of increasing the bit directional performance. Bit D provides an example of the science underlying the bit design. This bit retained the original format of eight blades and 16 mm and 19 mm cutters in the face, but the diamond density was reduced by 25% by spacing out the cutters. This cutter count reduction is equivalent to a six or seven blade bit design. The DxD analysis indicated that by reducing the diamond density but retaining the number of blades, the bit stability was not affected; by performing additional adjustments to the cutter layout, even the stability of the torque on bit (TOB) variation was improved. Figure 18 shows the R1 cutters on the bit and the spacing between the cutters. The DxD tool also enabled improved bit steerability of Bit D. This tool made it possible to simulate the actual drive system (point-the-bit), drilling parameters, and basic formation properties, and compared the previous Bit C design with that of Bit D. By changing the gauge configuration to create a step gauge and reducing the tip grinding of the gauge cutters (more lateral aggressiveness), the steerability was improved by 57%, as compared with Bit C. The graphs shown in Figs. 19 and 20 illustrate the results generated by DxD. Figure 21 shows the improved Bit D steerability. Improving the bit steerability means that the bit will require less side force to generate the planned doglegs; in extreme drilling conditions through hard formations, the PRSS tool output will be optimum in terms of doglegs. In soft and medium formations, the deflection on the PRSS shaft will be less, minimizing the stress on the tool and increasing its reliability. Fig. 17. R1 cutter in action – Ghawar field. Fig. 18. Bit D cutter distribution. Fig. 19. Bit steerability. SAUDI ARAMCO JOURNAL OF TECHNOLOGY SUMMER 2010 53
Page 3 and 4: Summer 2010 THE SAUDI ARAMCO JOURNA
Page 5 and 6: 24” CSG at 365 ft EPC 178,00#, X4
Page 7 and 8: Stage Depth (ft) Direction Fluid Vo
Page 9 and 10: The injectivity test, which can be
Page 11 and 12: REFERENCES 1. Moore, N.B.A., Kruege
Page 13 and 14: Next Generation Technologies for Un
Page 15 and 16: to 60 ft/hour with the hydraulic or
Page 17 and 18: improving drilling performance. The
Page 19 and 20: Robotics for Horizontal Image Acqui
Page 21 and 22: mud cap to TD at 10,100 ft. Open ho
Page 23 and 24: unning the operations by convention
Page 25 and 26: Stimulating Khuff Gas Wells with Sm
Page 27 and 28: Fig. 2. ACTive fiber optics. DESCRI
Page 29 and 30: • Treatment acid: 26% HCl acid (1
Page 31 and 32: 25 20 15 10 5 0 Well 1 Well 2 Produ
Page 33 and 34: Fig. A3. Post flush temperature res
Page 35 and 36: Wassim Kharrat has been working wit
Page 37 and 38: SAUDI ARAMCO EXPERIENCE WITH INCOMP
Page 39 and 40: eciprocated) along the axis of the
Page 41 and 42: then either continue running the as
Page 43 and 44: Application of Hydrajetting Technol
Page 45 and 46: Amount of Proppant (lb) 135,600 lb
Page 47 and 48: Development and Optimization of 12
Page 49 and 50: Vertical Section View 10,000 Well A
Page 51 and 52: Fig. 8. Powered rotary steerable sy
Page 53: needed a fit-for-purpose bit design
Page 57 and 58: performances in the 12” direction
Page 59 and 60: Jaywant Verma is a Drilling Enginee
Page 61 and 62: favorable economics of drilling sma
Page 63 and 64: orehole fluids. This tool can be co
Page 65 and 66: Fig. 6. Plot of a sidetracked (Well
Page 67 and 68: BIOGRAPHIES Izuchukwu “Izu” Ari
Page 70: GUIDELINES FOR SUBMITTING AN ARTICL

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