ENHANCED OIL RECOVERY - MODIFICATION AND CONTINUATION OF THE ARTICULATED DRILLSTRING | | Project | Fact sheet | ENG | CORDIS

Obiettivo

Main purpose of the R&D project TH/02047/87/DE is the development of a short downhole motor based on the existing ADS-system (Articulated Drill String) with the same high accuracy of azimuthal and directional control. The usability of the new system to drill horizontal wells from small diameter casings has to be achieved.
This target shall be reached by integration of short positive displacement motors into the ADS technology.
In addition, drilling and production related technologies shall be developed to optimize the completion of horizontal wells in hydrocarbon reservoirs.
The new articulated downhole motor (ADM) was constructed and fieldtested as a short positive displacement motor. After generally successful fieldtests of the 4,75" and 6,75" version of the ADM, improvement and optimization work has to be done. The design of the articulations had to be changed twice. The support pads on the articulations were extented to improve the build-up performance of the ADM, particularly in soft formations and unconoslidated sands. The edgeing rings of the rubber sleeve had to be revised in geometry and finish to improve the adhesion of the vulcanized hose. The load capacity of the articulation was improved by the adjustment of the bearing surface. The increased interest in an ADM with a reduced diameter to get the ability to drill short radius horizontal wells with radii down to 20 m from all common 7" API casings will be satisfied by a new ADM with a diameter of 4,15 only.
A MWD system which was developed by Preussag with a sponsorship of the German Ministry for Research and Technology is being modified to suit the requirements in short radius horizontal drilling. The now available MWD system shall be modified for use with the ADM in short radius horizontal drilling.
In long horizontal sections it is difficult to create the necessary weight on bit. The weight on bit is produced by means od drillcollars positioned in the vertical section of the borehole. The drillpipe located below the drillcollars has to transfer the load to the bit. Under these conditions drag and buckling of the drillpipe is a problem. Up to now in horizontal sections usually heavy-wall-drillpipe (HWDP) is used due to their increased bending resistivity compared to conventional drillpipe. The higher eight and the upset at the center of each joint result in the tendency of accumulation of cuttings in horiozntal sections. Therefore it can be difficult to reach bottom of the hole. This experience was made while drilling the short radius testwell Reitbrook 79 with ahorizontal length of 375 m. Fieldtests with lightweight aluminium drillpipe were not successful. A new flexible drillpipe made of non magnetic steel was built and tested sucessfully. Due to the high costs of the material this drillpipe can be used in the near bit area at the position of the MWD system only. Based on the a.m. requirements and problems a slick drillpipe with high bending resistance was designed.
A retrievable packer/whipstock assembly, which can be used to drill brnached horizontal wells, was constructed and run in a hole to test the retrieving mechanism successfully.
To predict the drag forces a computer model was developed. This model is based on the casing weight in drilling mud, the friction between borehole and casing and the dogleg severity. First testruns have shown significant differences between actual and calculated drag forces. To improve the model the drag forces caused by centralizers and the bending of the casing due to the curved hole were introduced.
The development consists of seven project stages related to three topics (subjects) :
1. Articulated drill string (ADS)
STAGE 1 : State - of - the - art report
STAGE 2 : Modification of the existing drill string, adaption of mud motor and flexible drill pipe
STAGE 3 : Adaption of the flexible drill string components and 2-way EM-MWD system
2. Flexible drill string
STAGE 4 : State - of - the - art report
STAGE 5 : Construction and testing of flexible drill string components
3. Completion and production methods
STAGE 6 : State - of - the - art report and theoretical solution of problems
STAGE 7 : Configuration, testing, modifications.

Programma(i)

ENG-HYDROCARB 2C - Programme (EEC) of support for technological development in the hydrocarbons sector, 1986-1989

Argomento(i)

1.2 - DRILLING

Invito a presentare proposte

Data not available

Meccanismo di finanziamento

DEM - Demonstration contracts

Coordinatore

PREUSSAG AG (EX SALZGITTER AG)

Contributo UE

Nessun dato

Indirizzo

ABTEILUNG FORSCHUNG ENTWICKLUNG POSTFACH 15 06 27
1000 Berlin
Germania

Costo totale