Drilling without pulling out drillpipes – drilling with casing

Past experience and present opportunities of Russian technology

We present "...the development of RB designs for DWPP with DHM in Russia during the past 50 years, including the latest research and field application in offshore stratigraphic drilling projects. This unique long-standing experiment allows us to estimate - with due regard for current mechanical engineering achievements - the possibility of using RB and relevant technology in modern drilling projects. Besides casing drilling, this include riserless drilling, geothermal drilling, and scientific drilling, both onshore and offshore."
(Advanced Drilling Solutions - Lessons from FSU; v. 2, chapter 7, PennWell books, 2003)

RETRACTABLE BIT TECHNOLOGY - SOLUTION FOR CASING DRILLING


Contents

DRILLING WITHOUT PULLING DRILLPIPES RESULTS:

  • OIL FIELD - Saratovneftegas 1953-1975
  • SCIENTIFIC ONSHORE - Sputnik SG-3 1973-1978; Krivoy Rog SG-8 1985-1992
  • DRILLING WITH CASING: Surgutneftegas 1974 TRB-300 for ODP onshore test 1994
  • SCIENTIFIC OFFSHORE - Atlantic 1991;
  • STRATIGRAPHIC OFFSHORE - Norway sea 1993; Gibraltar 1995

POSSIBLE APPLICATION NOVADAYS

  • DRILLING WITH CASING PIPES USING CONVENTIONAL RETROFITTED RIGS
  • DWC IN HARD ROCK
  • COMPLETE RBHAÕS AND COMPONENTS HAVE BEEN DEVELOPED FOR 13-3/8"; 9-5/8"; 7" AND 5" CASING STRINGS AQUATIC COMPANY

Concept

  • Subsequent to the development of rotary drilling and the increase of borehole depths, the concept of decreasing drillstring round-trip time to change the worn bit was discussed.
  • The development of a bit that could be run in and pulled out of the bottomhole inside the casing or drillpipe, using a wireline or drilling mud circulation was a logical solution.
  • These bits were used in two modes:
    (1) working - for bottomhole destruction
    (2) transport - for moving inside the pipe
  • The bit name, Retractable Bit (RB) derived of this application.
  • The use of RB allows drilling without pulling out the pipe (DWPP) and substantially affects the process of construction of a borehole or one of its intervals. DWPP features are as follows:
    • continuous flushing of the borehole during the RB operational cycle: running in, drilling, pulling out
    • replace of the different purpose tools (drilling, coring, and milling) without pulling out drillpipes
    • carrying out logging operations without pulling out drillpipes
    • relief of the workload on drilling rig crews
    • maintaining the traditional method of bit rotation by stiff drillstring and/or DHM
  • What need to be added for the well construction
    • more complicated bit design
    • special or larger ID flush joint drillpipe
    • special design BHA, both retrievable part (RBHA) and connected to drillstring
    • latch and seal unit for RBHA
    • drill rig retrofit by implementation equipment and accessories for RBHA tripping
  • DWPP includes drilling with casing as a subsystem
    • DWPP drillstring supposed to be a casing string
    • the real advantage of the RB technology - simultaneous borehole drilling and casing - drillpipes could be excluded from the drilling rig set
    • the quality of casing pipe and especially the thread connections in the past did not allow using them for DWPP, particularly in hard formations, but state of the art casing could allow such application
    • drilling with casing (DWC) trend of RB application is one of the major areas for implementation
    • DWC brought revolutionary changes in the entire drilling process

RB technology - first test (1952)


DWPP in Saratovneftegas - test wells

  • 1948-1956 - designing of the first retractable tools for 12" borehole; testing in separate intervals of well at the depth up to 1500 m;
  • 1957-1964 - the serial production of retractable bits and high RPM turbodrills with retrievable rotor for 10" borehole; drilling the test wells of 2100 and 2800 m depth;

DWPP in Saratovneftegas - commercial application

  • 1965-1971 - improving retractable bit and turbodrill designs and retrievable tools tripping process;
  • 26 exploratory and development wells of 2500-3000 m depth were drilled; the total footage made by retractable bits was nearly 41000 m in the interval of 1000-3000 m depth;
  • Time between the two bit runs was one hour: 8 to 9 bit runs per day at depths of 1800-2000 m.
  • 1967-1975 - development of 9" RB, retrievable PDM, turbodrills, coring and auxiliary tools design; drilling of exploratory wells to the depth up to 2800 m.

RB design

  • Step bit (1949-1952) Tri-cone pilot bit and two-cone expandable reamer
  • One-step BD-type RB (1953-1964) Two-cone bit with monolith (made in one piece) drill head
  • Two piston D2PV-type bit (1959-1968) Two-cone bit with separate legs and movable internal components in the mechanism
  • Bodiless DRB-type bit (1966-1970) Two-cone bit with movable external components in the mechanism
  • Tri-cone bodiless 3DR-type bit (1969-1975) External movable system featuring two holders for legs with cones and special arrangements for proper consequences of bit transfer

The ratio between transportation and operation position diameters is

  • More than 0.75 in mining type diamond RB
  • With DHM drilling is 0.66 with a rim-anchor for bit latching
  • 0.62-0.60 with landing shoulder application to latch the bit


Drilling with casing test in Surgut UBR (Drilling Co.), 1974-1975

245-mm casing string; turbodrill 195 OD two sections; 4-cone RB, interval drilled 25-400 m, ROP 57 m/hr


Sputnik SG-3 trials, Kola Peninsula

  • Drilling of 217-mm diameter boreholes in hard crystalline rock
  • The tools tested were:
    • Core heads and core barrels
    • Retractable blade reamer with diamond composite cutters (ISM)
    • Retractable TCI tri-cone bit
    • Retrievable turbodrills and PDM
    • Aluminum drill pipe ADP 168x11
  • During 1975-76, the complete tests were conducted in the 580-1316 m interval. Retractable tools were used to make 98 runs. A total of 324.2 m were drilled including 174 m with coring.
  • The commercial tests of TCI 3DR-217 bits of K, SZ, and OK types and RVA1-217 reamers with ISM cutting structure were carried out between 700 and 1100 m in 1977-1978.
  • Altogether, 35 runs with RB and 68 runs with RR confirmed the tool reliability for drilling hard rock.

Retractable diamond reamer test



Krivoy Rog SG-8 (1984-1992) scientific borehole drilling

DWPP coring technology was used in the 217-mm pilot borehole and 295-mm main borehole




REVERSE CIRCULATION ADVANTAGES:

  • no wireline and additional winch
  • high speed of retrievable tool running usually 2-3 m/sec down and 1-2m/sec upwards
  • continuous borehole flushing - cooling
  • best hydraulic regime to remove cuttings, especially from caverns, because of uniform cross-section area inside the pipes






DWPP-DWC basics: Retrievable bottomhole assembly (RBHA) with retractable drill bit(RB) and down-hole motor




Drilling with Casing considerations

  • DWPP original idea in 50s was casing drilling, but casing pipes were not suitable for drilling that time
  • CCS can be nowadays part of modern drilling with casing system (DWC)
  • DWC based on retractable bit and/or reamer application
  • Existing BHA and RBHA components can be used with 6-5/8", or 7" casing string
  • Continuous borehole flushing during an operational cycle:
    • running in and drilling - direct circulation
    • pulling out of hole by reverse circulation
    • pulling out of hole by combined wireline-reverse circulation
    • method to avoid lost circulation
  • Drilling through unstable formations and lost circulation zones
  • Pilot coring provides information on the trouble zones
  • Directional drilling capabilities exist