Implementation of geomechanical model to identify total loss zones

Transcription

1 SPE Workshop OILFIELD GEOMECHANICS Slide 1 Implementation of geomechanical model to identify total loss zones Session 3. Geomechanics for drilling and completion Kalinin Oleg Co-authors: Zhigulsky S.V.; Chebyshev I.S.; Martemyanov A.N.; Bazirov I.Sh.; Alchibaev D.V.; Lukin S.V.; Ovcharenko Yu.V. JSC "Gazpromneft NTC" March 27-28, 2017 Moscow, Russia

2 Slide 2 Analysis of the problems Basic information about the oilfield Analysis of total loss reasons Initial data for constructing of a geomechanical model Construction of 3D geomechanical model Prediction of total loss zones Conclusions Table of Contents

3 Slide 3 Analysis of the problems Catastrophic mud losses increases the construction period of the well Elimination of the effect of catastrophic mud losses increases unproductive time Companies incur losses Total loss zones are difficult to estimate and predict

4 Basic information about the oilfield Slide 4 The field is located in the Orenburg region The productive formation is Frasnian deposits of the Devonian system, presented sandstone reservoirs Catastrophic uptakes are recorded in the Famennian sediments represented by carbonate rocks The region is characterized by a complex structural and tectonic structure There is a clear zonation: the well with total loss of drilling mud is mainly located in the western part of the oilfield Well.1 Well.2 Well.3 Well.4 Total loss zone Wells with total loss recorded Wells without total loss recorded

5 Slide 5 Total loss reasons Drilling through faults Intensively fractured intervals Weak zones analysis Injection fracturing Different mechanisms of loss require different procedures for prevention or elimination!

6 Slide 6 Initial data for constructing of a geomechanical model Geology Drilling Logging Core testing Geological model Faults Tectonics Stratigraphic surfaces / horizons Fracture model Seismic Daily reports Data of drilling mechanics Wash Fluid Parameters Mud analysis Intake rate GR, RHOB Acoustics (P-wave, S- wave) Borehole Image Petrophysical interpretation Pressure measurements Macro/micro description of the core Petrophysical analysis Mechanical testing

7 Construction of 3D geomechanical model Slide 7 Mapping of major faults Seismic inversion Mapping of lowamplitude faults Clarification of the tectonic regime Confirmation by the image

8 Construction of 3D geomechanical model Slide 8 Calculation and calibration of a 3D geomechanical model Properties distribution Creating a skeleton

9 Prediction of total loss zones Slide 9 Crossing of the active fault area Some fault areas under the current stress state become active Mohr-Coulomb failure criterion was used

10 Confirmation Slide 10 Well 1. Total loss zone was forecasted in the interval m, Confirmed Well 2. Total loss was not predicted because well intersects inactive zone, there were no complications, Confirmed Well 4. Total loss was predicted in the interval of MD m, complete absorption was confirmed without circulation by well drilling. Confirmed Well 5. Total loss zone was not predicted because well intersects inactive zone, Confirmed by well drilling Well 3. Full absorption of drilling mud, the installation of cement bridges, lengthening the timing of the construction of the well. Confirmed Well 6. First version (blue) of the trajectory intersects active zone of the fault, after trajectory correction the well was successfully drilled. Confirmed

11 Intensively fractured intervals Slide 11 Construction of DFN, total loss analysis Actual losses during drilling coincide with fracture zones Trend - tectonic model; Application of the neural net; Good correlation with the actual drilling data; The trajectory does not intersect the fault; Zonality - in the northern part the oilfield fractures are developed more strongly

12 Weak zones analysis Slide 12 Identification of weak zones based on the tectonic model The problem wells are mainly located in the stretching zones

13 Slide 13 Injection fracturing Based on the 3D model, a 1D geomechanical models were constructed The analysis of drillability is conducted Low fracture start gradient is a sign of injection fracturing Recommendations for mud density are provided Recommendations for correcting the trajectory are provided Possible injection fracturing zone Possible injection fracturing zone

14 Slide 14 The key to reducing risks Analysis of the project trajectory according to the following criteria: Faults crossing Weak zones Intensively fractured intervals Injection fracturing

15 Slide 15 Conclusions As a result of the work, the main causes of catastrophic losses were found 4 mechanisms for reducing drilling risks were developed According to the results of work performed, the unproductive time due to total loss of the drilling mud declined by more than 6 times

16 SPE Workshop OILFIELD GEOMECHANICS Slide 16 Thank you for attention March 27-28, 2017 Moscow, Russia

17 Slide 17 Additional slides

18 Slide 18 Additional slides