Lesson 35 Wellbore Surveying Methods PETE 411 Well Drilling Lesson 35 Wellbore Surveying Methods

Wellbore Surveying Methods Average Angle Balanced Tangential Minimum Curvature Radius of Curvature Tangential Other Topics Kicking off from Vertical Controlling Hole Angle

Read: Applied Drilling Engineering, Ch.8 (~ first 20 pages) Projects: Due Monday, December 9, 5 p.m. ( See comments on previous years’ design projects )

Homework Problem #18 Balanced Cement Plug Due Friday, December 6

I, A, DMD

Example - Wellbore Survey Calculations The table below gives data from a directional survey. Survey Point Measured Depth Inclination Azimuth along the wellbore Angle Angle ft I, deg A, deg A 3,000 0 20 B 3,200 6 6 C 3,600 14 20 D 4,000 24 80 Based on known coordinates for point C we’ll calculate the coordinates of point D using the above information.

Example - Wellbore Survey Calculations Point C has coordinates: x = 1,000 (ft) positive towards the east y = 1,000 (ft) positive towards the north z = 3,500 (ft) TVD, positive downwards C C N (y) N Dz Dz D D Dy E (x) Dx

Example - Wellbore Survey Calculations I. Calculate the x, y, and z coordinates of points D using: (i) The Average Angle method (ii) The Balanced Tangential method (iii) The Minimum Curvature method (iv) The Radius of Curvature method (v) The Tangential method

The Average Angle Method Find the coordinates of point D using the Average Angle Method At point C, x = 1,000 ft y = 1,000 ft z = 3,500 ft

The Average Angle Method C N (y) C Dz D N Dz D E (x) Dy Dx

The Average Angle Method

The Average Angle Method This method utilizes the average of I1 and I2 as an inclination, the average of A1 and A2 as a direction, and assumes the entire survey interval (DMD) to be tangent to the average angle. From: API Bulletin D20. Dec. 31, 1985

The Average Angle Method

The Average Angle Method

The Average Angle Method At Point D, x = 1,000 + 99.76 = 1,099.76 ft y = 1,000 + 83.71 = 1,083.71 ft z = 3,500 + 378.21 = 3,878.21 ft

The Balanced Tangential Method This method treats half the measured distance (DMD/2) as being tangent to I1 and A1 and the remainder of the measured distance (DMD/2) as being tangent to I2 and A2. From: API Bulletin D20. Dec. 31, 1985

The Balanced Tangential Method

The Balanced Tangential Method

The Balanced Tangential Method

The Balanced Tangential Method At Point D, x = 1,000 + 96.66 = 1,096.66 ft y = 1,000 + 59.59 = 1,059.59 ft z = 3,500 + 376.77 = 3,876.77 ft

Minimum Curvature Method b

Minimum Curvature Method This method smooths the two straight-line segments of the Balanced Tangential Method using the Ratio Factor RF. (DL= b and must be in radians)

Minimum Curvature Method The Dogleg Angle, b, is given by: cos b = 0.9356 b = 20.67o = 0.3608 radians

Minimum Curvature Method The Ratio Factor,

Minimum Curvature Method

Minimum Curvature Method

Minimum Curvature Method

Minimum Curvature Method At Point D, x = 1,000 + 97.72 = 1,097.72 ft y = 1,000 + 60.25 = 1,060.25 ft z = 3,500 + 380.91 = 3,880.91 ft

The Radius of Curvature Method

The Radius of Curvature Method

The Radius of Curvature Method

The Radius of Curvature Method At Point D, x = 1,000 + 95.14 = 1,095.14 ft y = 1,000 + 79.83 = 1,079.83 ft z = 3,500 + 377.73 = 3,877.73 ft

The Tangential Method

The Tangential Method

The Tangential Method

Summary of Results (to the nearest ft) x y z Average Angle 1,100 1,084 3,878 Balanced Tangential 1,097 1,060 3,877 Minimum Curvature 1,098 1,060 3,881 Radius of Curvature 1,095 1,080 3,878 Tangential Method 1,160 1,028 3,865

Building Hole Angle

Holding Hole Angle

CLOSURE (HORIZONTAL) DEPARTURE LEAD ANGLE

b

Tool Face Angle