Objective
The purpose of drilling for oil is twofold : first of all, to define, within the best safety and performance conditions taking into account time and cost, the best adapted technical facilitites for the production of hydrocarbons, and also to acquire the best possible knowledge of the formation that is drilled.
An appreciable reduction in cost may be attained by constant mastery (via data acquisition, interpretation and modelling) of the essential drilling parameters through the surface and downhole measurements, and by using this data to optimize drilling operations. It is then possible to practically automize these operations for optimal control of the drilling rig developed and designed by EUROFOR.
a) Drilling measurement
- The result of the analysis and of the interpretation of the gaseous index measurements show that a non permanent efficiency of the degasser, although improved, does not allow to clarify the relative variations of different gas due to the drilling conditions or the mud formation exchange.
- No conclusive results of the study of the pore pressure estimation and no results of the study of the gas plugs at the drill pipe connection.
- The last tests on drilling bench, instead of the planned tests, have led to propose a wear criterion of drill bit and a method to analyse its evolution, to be confirmed by effective drillings.
- Encouraging results were obtained concerning the study of the dynamic reservoir permeability during the well drilling, with the MWD resistivity logs. Nevertheless, an extended application of the method remains difficult and needs to define drilling program specifications and modelling developments of the phenomena.
b) Drilling hydraulics
- The results of numerical simulation works and of experimental works led to validate the flow calculation chain for a drill bit with a simple shape. The study of a complex geometry bit is not completed.
- The calculation model of the parameters to optimize the cutting removal in deviated wells has been improved and validated by experimental results, but this model remains in the state of a research tool.
- A model to determine the annular pressures during drilling fluid circulation and during tripping has been validated with the experiments conducted on a large scale experimental site.
- The results of the well bore erosion study were not conclusive, related to the experiment difficulties.
- The numerical modelling of pressure and flow pattern inside permeable formations underneath the bit working face was developed with a first tentative of validation by experiments on the drilling bench.
c) Trajectory control
Trajectory selection : achievement of two softwares, tested and calibrated, with their operating and user manuals : FRISSON, friction model and COTRAO, trajectory design model.
- Trajectory realization : achievement and installation of further software developments in ORPHEE 3.D software. An using licence is expected.
Trajectory monitoring : achievement of two softwares, tested and calibrated with their operating and user manuals : ELLINC, model of uncertainty ellipse calculation, and INTERMAG, model of magnetic correction calculation on azimut measurements.
- The integration of these softwares within a computer tool to help in well trajectory design, selection and realization was not performed. The achievement of such a technical objective is an ambitious goal, requiring more important means than those which have been provided for inside the present project.
d) New drilling system
The interruption of the EUROFOR project has not allowed to make the integration of the results of the project Nr. TH./02050/88.
a) Drilling mesurement (MESFOR)
- approximation of gaseous indexes via quantitative measurement of a representative surface parameter and its relation to the reservoirs crossed as indicated by statistical studies.
- pore pressure evaluation by introducing correction or lithologic factors, deduced from MWD well logs, in the calculation module, as well as drill bit wear laws under the given drilling fluid rheological conditions,
- the study of gas at rod connection time as overpressure indicator by modelling of the phenomenon,
- the definition, through site measurement campaign, of the drill bit wear laws that intervene in the decision to replace the drill bit and to correct the feed speed for pore pressure calculation,
- the estimation of the stratum relative permeability based on an interpretation of the resistivity well logging during drilling and on an invasion modelling of previous strata.
b) Drilling hydraulic (HYDROFOR)
- stabilizer and drill bit hydraulic : validation and optimization of the flow calculation chain for simple pattern drill bit and its extension to complex pattern drill bit. This modelling will make it possible to determine the preponderant criteria and to study the effect of the various parameters, then to seek optimized patterns validated on benches and on the site.
- well cleaning and the use of hydraulic power : validation and utilization, during specific tests or on site, of an annular pressure determination model and of a model for upraising of well cuttings in inclined wells, hydraulic well erosion studies and research on prevention methods.
- hydraulics at working face : validation of the numerical model (in Phase 1) via tests on the drilling bench then the study of the effect of stratum permeability and of transient factors on the rate of penetration for various drilling fluids.
c) Trajectory control (MAITRAJ)
- trajectory selection : - study of friction and development of a calculation software,- development of a well profilecalculation module, - characterization of the effect of seam and structure dip on the drillstring behaviour.
- trajectory calculation : this study of the physics of directional drilling will lead to improved prediction of drill string behaviour by :
. developing numerical models, one of which will analyse drilling process integration in the load calculation, using the drill string models
. adjusting numerical models using a complete range of tests on a test bench, on actual wells under controlled experimental conditions and on actual wells under operational conditions,
. simulating the role of the stratum on drill string behaviour, by bench tests and by statistical analysis of actual drillings.
- trajectory control : the development works will consist in establishing the anti-collision criteria to be introduced in uncertainty ellipse calculation.
d) New drilling system (EUROFOR)
- Integration of methods, procedures, software and optimization of the control of the new automatic drilling rig.
Programme(s)
Topic(s)
Call for proposal
Data not availableFunding Scheme
DEM - Demonstration contractsCoordinator
92500 Rueil Malmaison
France