HORIZONTAL DRILLING TECHNOLOGY KEEPS ADVANCING

Guntis Moritis
Drilling/Production Editor

The upward surge in horizontal drilling projects shows no signs of slackening and innovative applications of the technique continue.

Dual horizontal laterals are the latest innovation that may accelerate the spread of horizontal drilling.

Horizontal drilling in 1990 increased markedly over the previous year, according to the Journal's latest survey conducted with its Energy Data Base group. The survey shows over 460 wells that have not appeared in OGJ's previous two surveys. Most of these wells had horizontal laterals greater than 1,000 ft in the reservoir.

In addition, operators indicated that they drilled 62 horizontal wells with laterals less than 1,000 ft.

Because of the large number of wells drilled, a tabulation of the survey is not included in this issue. Information on obtaining a complete listing is available from the OGJ Energy Data Base.

The number of wells listed is a substantial increase from the 135 in last year's survey and represents about half of the estimated 1,000 horizontal wells drilled in 1990.

The main thrust of horizontal drilling remains centered on the Austin chalk trend in Texas and the Bakken shale of North Dakota. No new areas have appeared that can rival these in the number of horizontal wells. But the potential is there.

Both Canada and Wyoming will see more activity in 1991. And horizontal wells will be drilled in such diverse areas as Gabon, Congo, U.K., Indonesia, Denmark, Zaire, Germany, Australia, The Netherlands, and Trinidad.

The rapid growth in activity is also indicated by the Texas Railroad Commission granting 1,098 horizontal well permits during 1990. This is 84.6% of the total 1,298 granted in Texas since the first one in 1984.

A sizable drilling backlog exists in Texas. Only 546 horizontal wells, 42% of those permitted, had been completed by December 1990.

DUAL LATERALS

For the first time, dual lateral wells are included in the survey. This type of multiple-drain well is expected by some to eventually represent a significant portion of horizontal wells.

All three of the dual wells listed in the survey were drilled in the Austin chalk of the Pearsall field.

In the Cox & Perkins Well No. 2, one 1,310-ft lateral was drilled at 6,745 ft. The length of the other lateral at 6,783 ft was 1,400 ft. The well took 95 days to drill and complete.

Production from this well is with a rod pump through one string of tubing. No production figures were made available.

Petro-Hunt Corp. drilled the M.R. McDermond No. 1 dual well in 46 days. The downdip lateral is 3,164 ft long at a depth of 7,037 ft. In the opposite direction, the updip lateral extends 2,305 ft at 6,898 ft.

An electric submersible pump was producing the well at a rate of 2,292 bo/d, 384 bw/d, and 1.65 MMcfd of gas.

A dry-hole dual lateral was drilled by Wolverine Exploration. Its Wagner 155-1-H was drilled in 43 days. The upper lateral, at 6,093 ft, had a horizontal displacement of 3,500 ft. The lower lateral was 2,676 ft, at 6,21 0 ft.

1991 PLANS

This year will be another active year for horizontal drilling. Our respondents indicate that 736-777 horizontal wells will be drilled with horizontal laterals greater than 1,000 ft in length. Another 43-45 wells are planned with laterals less than 1,000 ft (see table).

Considering the continuing boom in the Austin chalk and the number of small companies involved, the actual number could easily be twice as many.

In 1991, Union Pacific Resources Co. is planning to drill 135 horizontal wells, more than any other survey respondent. Most of these wells, 115, will be in the Austin chalk trend of Texas. The other 20 are planned for the Niobrara formation in Wyoming. A number of analysts have predicted that the Niobrara formation of Wyoming and Colorado has the potential of becoming the next hot area for horizontal drilling.

Meridian Oil Inc. and Oryx Energy Co. are two companies that have been very active in the past and will continue to have vibrant programs. Meridian plans between 45 and 50 wells in Texas and North Dakota. Oryx has plans for 50 or more wells at unspecified locations.

Petro-Hunt plans to triple its activity to 60-75 horizontal wells in 1991. In 1990, it drilled 22 wells.

Conoco Inc. is another company whose program will substantially increase. It plans to drill 55 wells in 1991, up from 13 in 1990.

Mobil Oil Corp. has one of the more diverse programs planned for 1991. It includes drilling horizontal wells in the North Sea, Canada, Germany, Gulf of Mexico, Indonesia, and Texas.

RECORDS

In 1990, Elf Aquitaine Petroleum's well C-2 offshore The Netherlands, Block L-7, had the deepest true vertical depth (TVD) at 13,322 ft. The length of the horizontal was a short 305 ft at 95, although the horizontal displacement was 1,050 ft.

For wells with laterals longer than 1,000 ft, Marathon Oil U.K. Ltd. drilled, in the North Brae field, a 92, 1,615-ft horizontal at a TVD of 12,640 ft.

In last year's survey, Nederlandse Aardolie Mij. BV (NAM) was listed with the deepest horizontal lateral. Its well in Block L-13, offshore The Netherlands, was drilled at a TVD of 11,484 ft.

None of the wells in this year's survey match the horizontal length in the reservoir or horizontal displacement of Unocal Corp.'s A-16 well, drilled offshore California in 1989. That well had a horizontal displacement of 12,740 ft and a length in the reservoir of 5,743 ft. Maximum inclination angle was 87.5.

The longest horizontal displacement in this year's survey is Elf's well in the Buffalo field, offshore Angola. Horizontal displacement was 9,104 ft with a horizontal lateral extending 4,429 ft. Maximum angle was 90.9.

Meridian's Pearsall field well No. 1-337H, 5,208-ft horizontal lateral, was the longest in this year's survey.

The well with the greatest maximum angle this year was Amoco Canada Petroleum Co. Ltd.'s Sturgeon Lake South No. 2. The well, with a short 200-ft horizontal lateral, climbed to an inclination of 121. The TVD was 8,300 ft.

This year's survey did not include any well that matched the production rate of 30,000 bo/d reported last year for Norske Hydro's Troll field horizontal test well. The most prolific oil producer listed was Mobil Oil's Ness field well 9/13b-49, in the U.K. portion of the North Sea. The production was given as 16,000 bo/d and 8.25 MMcfd.

Another prolific horizontal producer was Marathon Oil's North Brae field well B-17, 10,000 bo/d, also in the U.K. North Sea.

In the Pearsall field, GLG Energy reported the best oil producer. Its well Petty No. 1 produced at a rate of 3,340 bo/d and 0.3 MMcfd. The well has an electric submersible pump.

Texaco had three Gulf of Mexico horizontal gas wells under test. Its East Cameron well B-14 was producing 18 MMcfd, well B-12 was producing 12 MMcfd, and the South Marsh Island well D-10 was producing 10.3 MMcfd. The East Cameron well B-14 is at a shallow TVD of 1,768 ft, but the South Marsh Island well is much deeper at 10,087 ft TVD.

Amoco had one of the more unusual motives for drilling a horizontal well. "Under town" was listed as the reason for drilling its Salt Creek field well, in Natrona County, Wyo.