Objective
The aim of the project is to develop a new positive displacement multi-lobe motor for a very specific market requirement; directional drilling in large diameters 14 3/4" - 17 1/2" - 26". The motor presents an original concept as the outer cylindrical motor housing turns around a non-rotating but nutating helical shaft locked in the body by non-rotating universal joint. This permits direct driving of the drill bit by a concentric rotating assembly stabilized in the outer supporting sleeve. The main advantages expected from this new concept are achieving a better life for the bearing assembly and thereby of the motor itself, supressing rotating universal joint and shortening the tool making it more adapted to directional drilling. Due to its advantages, the motor gives a better conduct of directional drilling, allowing a reduction in the cost of development drilling.
Following feasibility and field test (150 hours) no ruptures or trouble were detected.
Meanwhile we have found :
- Abnormal wear in the stuffing box,
- Premature wear of cell elastomers,
- The sealing grease box round the universal joint has been detective.
Solutions :
- Laboratory comparative tests of the stuffing box packing ring made of different sintered alloies,
- Monobloc motor cell with thickness of elastomers doubled. The shaft helical line increased by 40% with the object of reducing the elastomers stress,
- Adapt a sleeving round the universal joint.
A laboratory research must be considered to select :
- The hardness and nature of elastomers,
- The quality of the elastomers joining with the supporting sleeve,
- Metallurgical components of the stuffing box friction parts (choice of material, sintered alloies, hard facing and metallurgical hardening).
A feasibility prototype of the motor was ready in 1983 with the purpose of assessing mechanical characteristics of the motor cell.
Computer data were obtained in the SHELL test bench in 1984. This feasibility prototype has been modified and reconditioned for the manufacturing of a field prototype. Test runs were made with ELF-AQUITAINE in 1985-1986.
This prototype features the following particularities :
- A new assembly in a supporting sleeve with 11 1/4" O.D wall thickness 1", and tapered threads.
- A new concept of the rotating allowing the establishment of suitable elastomers, as well as the quality of bonding between the elastomers and the rotating housing.
- A new concept of rotating seal to reduce wear in the stuffing box.
- Increased capacity of the bearing assembly by adding to the number of thrust surfaces carrying the axial load.
Following the previous results, a more adapted field prototype is to be produced in order to increase performance. It will be distinguished by :
- A motor cell made in one piece with thicker elastomers.
- A better size of the mechanical pieces to achieve a more important flow rate (from 3 000 litres/minute to 4 000 litres/minute).
- Technical improvements :
- Bearing assembly interchangeability,
- Universal joint sealing,
- Stuffing box longer life (packing ring).
It is necessary to reach a minimum of 100 hours rotating time to consider this motor operational and be able to market it.
Programme(s)
Topic(s)
Call for proposal
Data not availableFunding Scheme
DEM - Demonstration contractsCoordinator
65421 IBOS - TARBES
France