Slim-Hole Drilling in Harsh Environments
- J.D. Fultz (SlimDril Intl. Inc.) | F.J. Pittard (SlimDril Intl. Inc.) | F.D. Sawyer (Sandefer Offshore Operating Co.) | W.R. Farmer (Union Exploration Partners)
- Document ID
- Society of Petroleum Engineers
- SPE Drilling Engineering
- Publication Date
- September 1991
- Document Type
- Journal Paper
- 225 - 229
- 1991. Society of Petroleum Engineers
- 5.3.4 Integration of geomechanics in models, 1.14 Casing and Cementing, 1.6.2 Technical Limit Drilling, 1.10.1 Drill string components and drilling tools (tubulars, jars, subs, stabilisers, reamers, etc), 1.6.5 Drilling Time Analysis, 1.11 Drilling Fluids and Materials, 1.11.2 Drilling Fluid Selection and Formulation (Chemistry, Properties), 1.6 Drilling Operations, 1.6.1 Drilling Operation Management, 4.1.2 Separation and Treating, 1.5 Drill Bits, 4.1.5 Processing Equipment, 3 Production and Well Operations, 2 Well Completion
- 0 in the last 30 days
- 209 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 5.00|
|SPE Non-Member Price:||USD 35.00|
Wells with small liners occasionally require unique methods of drilling, completion, and reworking, especially deep-hole wells and wells with severe doglegs. Innovative drilling procedures were used successfully on two wells with those downhole conditions. On the first well, cement was drilled in a 3 1/2-in. liner with a small mud motor and heavyweight mud. On the second well, a large mud motor was used as a downhole power swivel to drill in a 3 1/2-in. liner. Both jobs were completed at depths of 13,000 to 20,000 ft with mud weights >18 Ibm/gal and bottomhole temperatures (BHT's) > 300deg.F.
SlimDril Intl. Inc., Sandefer Offshore Operating Co., and Union Exploration Partners have field-proved two methods of slim-hole drilling in harsh environments. For this study, a harsh environment is one that exhibits one or more of the following conditions: mud weight >17 lbm/gal, depth >15,000 ft, and BHT >300deg.F.
The first job was completed for Sandefer Offshore Operating Co. The job, which took place on a jackup rig in the Gulf of Mexico, required removal of about 300 ft of cement in a 5-in. liner and removal of about 800 ft of cement in a 3 1/2-in. liner. High bottom-hole gas pressure was expected; therefore, an 18-lbm/gal waterbased drilling fluid was used. This job was successfully completed with 3 3/8 and 1 3/4-in. positive-displacement motors (PDM's). The second job was completed for positive-displacement motors (PDM's). The second job was completed for Union Exploration Partners. This job, which took place on a barge rig in the inland waterways of Louisiana, required that we deepen a hole from 19,400 to 20,000 ft and then clean out a 3 1/2 -in. liner from 19,000 to 20,000 ft. BHT's were greater than 300 " F and the mud weight was 19 Ibm/gal. The job was completed successfully with 3 1/2 -in. PDM's designed for straight-hole drilling applications. The PDM's were used as downhole power swivels to rotate 1,000 ft of 1 1/4-in. workstring.
Each bottomhole assembly (BHA) used on these two jobs was some combination of the high-performance tools described below.
Diamond Bits. Two types of diamond bits are used with the slim-hole drilling system. Sidetracking matrix bits with short gauges and natural diamonds are typically used to kick off from vertical wells and are designed to provide a rugged cutting surface while kicking off a cement plug or whipstock. plug or whipstock. Matrix-body bits, with either natural or thermally stable poly-crystalline diamonds (TSD's) (Fig. 1), are used to drill straight poly-crystalline diamonds (TSD's) (Fig. 1), are used to drill straight deviated, or horizontal wells. A large number of diamonds are used on the gauge of the bits to provide (1) good sidecutting, (2) high rates of penetration (ROP's), and (3) long life in deviated sections of the hole. penetration (ROP's), and (3) long life in deviated sections of the hole. These bits are designed specifically for use with high-speed PDM'S. They virtually eliminate vibration problems experienced with polycrystalline-diamond-compact (PDC) bits on highspeed motors. In 1985, polycrystalline-diamond-compact (PDC) bits on highspeed motors. In 1985, Austin Chalk wells were drilled at rates of 7 to 10 ft/hr with conventional straight-hole diamond bits, compared with current drilling rates of 20 to 30 ft/hr with the newly designed high-temperature TSD bits.
Carbide Mill Bit. The wavy-bottom carbide mill bit (Fig. 2) is commonly used on workovers involving metals and cement. This type of mill bit has several advantages over flat-bottom and blade mill bits. The wavy profile gives more aggressive cutting action on iron and other metals and does not experience severe stalling or wear associated with blade mill bits. The aggressive nature of the wavy profile provides high ROP's in cement when the mill bits are used on high-speed PDM'S. The ability of this mill-bit/mudmotor combination to drill both metal and cement effectively allows many jobs to be completed with one bit, eliminating the need to make trips to change bits or BHA'S.
|File Size||696 KB||Number of Pages||5|