EVALUATING THE IMPACTS IN THE PRODUCTIVITY OF HIGH ANGLE WELLS CAUSED BY ...

151 Pages·2014·5.51 MB·English

EVALUATING THE IMPACTS IN THE PRODUCTIVITY OF HIGH ANGLE
WELLS CAUSED BY GEOMETRICAL CHANGES IN THE WELL TRAJECTORY

Diogo Câmara Salim

Dissertação de Mestrado apresentada ao
Programa de Pós-graduação em Engenharia
Civil, COPPE, da Universidade Federal do
Rio de Janeiro, como parte dos requisitos
necessários à obtenção do título de Mestre
em Engenharia Civil.

Orientadores: José Luis Drummond Alves
Paulo Couto

Rio de Janeiro
Setembro de 2014
EVALUATING THE IMPACTS IN THE PRODUCTIVITY OF HIGH ANGLE
WELLS CAUSED BY GEOMETRICAL CHANGES IN THE WELL TRAJECTORY

Diogo Câmara Salim

DISSERTAÇÃO SUBMETIDA AO CORPO DOCENTE DO INSTITUTO ALBERTO
LUIZ COIMBRA DE PÓS-GRADUAÇÃO E PESQUISA DE ENGENHARIA
(COPPE) DA UNIVERSIDADE FEDERAL DO RIO DE JANEIRO COMO PARTE
DOS REQUISITOS NECESSÁRIOS PARA A OBTENÇÃO DO GRAU DE MESTRE
EM CIÊNCIAS EM ENGENHARIA CIVIL.

Examinada por:

________________________________________________
Prof. José Luis Drummond Alves, D.Sc.

________________________________________________
Prof. Paulo Couto, Dr. Eng.

________________________________________________
Prof. Virgilio José Martins Ferreira Filho, D.Sc.

________________________________________________
Prof. Patrick William Michael Corbett, Ph.D.

RIO DE JANEIRO, RJ - BRASIL
SETEMBRO DE 2014
Salim, Diogo Câmara

Evaluating The Impacts in The Productivity of High Angle

Wells Caused By Geometrical Changes In The Well Trajectory /

Diogo Câmara Salim. – Rio de Janeiro: UFRJ/COPPE, 2014.

XVI, 135 p.: il.; 29,7 cm.

Orientadores: José Luis Drummond Alves

Paulo Couto

Dissertação (mestrado) – UFRJ/ COPPE/ Programa de

Engenharia Civil, 2014.

Referências Bibliográficas: p. 117-119.

1. Simulação Numérica de Reservatórios. 2. Perfuração de

Poços Horizontais. 3. Geodirecionamento. I. Alves, José Luis

Drummond et al. II. Universidade Federal do Rio de Janeiro,

COPPE, Programa de Engenharia Civil. III. Título.

iii
ACKNOWLEDGEMENTS

This work is humbly dedicated to my father, Jose Salim, my mother Josineide, my
sisters Isabela and Iana, my wife Evie, and my beloved children Lucas and Maria Luiza.
First of all, I am grateful to God for granting me the spiritual strength essential to
overcome the obstacles encountered along my route, regardless how challenging they
can become. I am eternally thankful to my parents for providing me with unconditional
love, education and confidence, for giving me the support in every single step of my
life. To my sisters, who always encourage me with vivacity to pursue my personal and
professional dreams. I am grateful to my wife, for her understanding and fortitude,
enabling me to giveaway precious moments of our family to accomplish such task. To
my treasures Lucas and Maria Luiza, whose intrinsic joy brings an extra taste for
inspiration in my work.
I would like also to thank my professors, José Luis Alves and Paulo Couto, for
their academic guidance and advices but also for their friendship through all these years.
Finally to my company, Schlumberger Brazil, that has kindly granted me available time
and support necessary to efficiently work on my Master program.

iv
Resumo da Dissertação apresentada à COPPE/UFRJ como parte dos requisitos
necessários para a obtenção do grau de Mestre em Ciências (M.Sc.)

AVALIANDO OS IMPACTOS NA PRODUTIVIDADE DE POÇOS HORIZONTAIS
CAUSADOS POR MUDANÇAS GEOMÉTRICAS NA TRAJETÓRIA DO POÇO

Diogo Câmara Salim

Setembro / 2014

Orientadores: José Luis Drummond Alves
Paulo Couto
Programa: Engenharia Civil

O objetivo da dissertação é avaliar os impactos na produtividade gerados por
mudanças geométricas na trajetória dos poços através do uso de simulação númerica de
reservatório. O trabalho de pesquisa é dividido em duas partes distintas. A primeira
consiste no desenvolvimento de um modelo sintético de reservatório, onde simulações
numéricas foram usadas em cada tipo de trajetória. Em seguida, uma análise de
sensibilidade é realizada comparando os resultados de cada caso a fim de identificar
uma relação entre posicionamento geométrico do poço com a resposta da produtividade.
A segunda parte trata-se de um caso real onde é aplicado a técnica de perfuração
de Geonavegação. Ao redor da trajetória planejada e do poço executado, é criado um
modelo de reservatório, aprimorado por meio da integração do modelo geológico
tridimensional juntamente com dados de LWD. Posteriormente, são realizadas
simulações de reservatório para avaliar os impactos causados devido às variações na
trajetória, demonstrando os resultados esperados de produtividade da trajetória
planejada comparados às previsões do poço executado.
Este estudo demonstra que ocorrem impactos na produtividade quando a trajetória
está sujeita a variações geométricas. Portanto, tal fato reforça que previsões na produção
não sejam apenas efetuadas na fase de planejamento, mas sobretudo após a conclusão
dos poços, fazendo-se uso dos novos dados coletados na perfuração. Ao integrar novas
informações, aprimora-se o entendimento do reservatório e logo possibilitando uma
análise de produtividade do poço horizontal mais eficiente e precisa.
v
Abstract of Dissertation presented to COPPE/UFRJ as a partial fulfillment of the
requirements for the degree of Master of Science (M.Sc.)

EVALUATING THE IMPACTS IN THE PRODUCTIVITY OF HIGH ANGLE
WELLS CAUSED BY GEOMETRICAL CHANGES IN THE WELL TRAJECTORY

Diogo Câmara Salim

September / 2014

Advisors: José Luis Drummond Alves
Paulo Couto
Department: Civil Engineering

The objective of this dissertation is to evaluate the impacts in the productivity
generated by geometrical changes in the well trajectory through numerical reservoir
simulation. The research work is then divided into two parts. The first one is the
creation of a representative synthetic reservoir model where numerical simulations are
applied for each trajectory design. A detailed sensitivity analysis is made by comparing
results among the different trajectory cases to identify relationship between well
positioning and its productivity response.
The second part consists of a real geosteering case study. Around both planned
and executed wellbores, it is then created a detailed reservoir model enhanced by a
comprehensive three-dimensional geological model together with LWD measurements
acquired in the pilot and executed wells. Afterwards, reservoir simulations are
performed in order to evaluate the impacts caused by the trajectory variations,
demonstrating the expected productivity results from the planned trajectory versus the
predicted ones of the executed well.
This research study shows that there is a productivity impact in all reservoir fluids
when well trajectory is subjected to geometrical variations. Thus it reinforces that
predictions related to reservoir production should not only be performed on planning
stage, but most importantly after well conclusion using relevant inputs, such as the
actual well path, LWD logs, and formation pressures while drilling, which all combined
provides an enhanced reservoir model, and so a more accurate forecast analysis.
vi
INDEX

1. INTRODUCTION .............................................................................................................. 1
1.1 MOTIVATION .................................................................................................................... 3
1.2 OBJECTIVES ...................................................................................................................... 4
2. ADVANCED WELL DRILLING, RESERVOIR ENGINEERING FOR HORIZONTAL
WELL & NUMERICAL SIMULATION LITERATURE REVIEW .................................................. 7
2.1 WELL PLACEMENT DRILLING METHODOLOGY ................................................................. 7
2.2 THE GEOLOGY AND WELL DESIGNS MODELLING PLATFORM ........................................ 10
2.3 OIL RECOVERY MECHANISMS & WATER INFLUX MODELS ............................................ 11
2.3.1. Rock and Liquid Expansion .................................................................................. 12
2.3.2. Gas Cap Drive ...................................................................................................... 12
2.3.3. Water Drive .......................................................................................................... 13
2.3.4. Water Influx Models ............................................................................................. 14
2.4 RESERVOIR ENG. CONCEPTS APPLIED FOR HORIZONTAL WELLS ................................... 17
2.4.1 Horizontal Well Definition as per Reservoir Engineering Aspects ........................... 17
2.4.2 Horizontal Well Drainage Area ................................................................................ 18
2.4.3 Effective Wellbore Radius (r’w) ................................................................................ 19
2.4.4 Productivity Index (j) ................................................................................................ 20
2.4.5 Critical Rate (q ) ....................................................................................................... 22
o
2.4.6 Analytical Approaches for Horizontal Well Simulation ............................................ 23
2.4.6.1 The Steady-State Analytical Solutions .................................................................. 23
2.4.6.2 The Pseudo-Steady State Analytical Solutions ..................................................... 25
2.5 PREVIOUS NUMERICAL SIMULATION STUDIES APPLIED IN ADVANCED WELLS .............. 26
2.6 ECONOMIC AND RISK FACTORS APPLIED IN DEEP-WATER DRILLING OPERATIONS OF
HIGH ANGLE WELLS .............................................................................................................................. 27
2.7 THE NUMERICAL RESERVOIR SIMULATION .................................................................... 29
2.7.1 The ECLIPSE Simulator ........................................................................................... 34
2.7.2 Brief Comparison of Numerical Reservoir Simulators ............................................. 36
3. DEVELOPMENT OF THE SYNTHETIC RESERVOIR MODELS ............................. 39
3.1 ANTICLINE TRAP SANDSTONE SYNTHETIC GEOLOGICAL MODEL ................................... 39
3.2 THE GEOMETRY DESIGNS OF THE HIGH ANGLE WELLS ................................................. 41
3.3 CONCEPTION OF THE SYNTHETIC RESERVOIR MODEL .................................................... 42
3.4 SENSITIVITY ANALYSIS OF THE PRODUCTIVITY RESPONSE CAUSED BY TRAJECTORY
CHANGES IN HIGH ANGLE WELLS .......................................................................................................... 43
3.4.1 Sealed-Boundaries Reservoir Model without Aquifer & Gas-Cap ........................... 43
vii
3.4.2 Laterally-Sealed Boundaries Reservoir Model with Carter Tracy Bottom Aquifer &
No Gas Cap .................................................................................................................................. 56
3.4.3 Sealed-Boundaries Reservoir Model with Gas-Cap.................................................. 74
3.4.4 Reservoir Model with Gas-Cap and Carter Tracy Aquifer ....................................... 80
3.5 SUMMARY OF THE SCENARIOS PERFORMANCE RESULTS ................................................ 90
4. SIMULATED PRODUCTIVITY ANALYSIS OF REAL CASE STUDY OF HIGH
ANGLE WELLS ................................................................................................................................ 94
4.1 OILFIELD GEOGRAPHICAL INTRODUCTION ..................................................................... 94
4.2 THE ORIGINAL DRILLING WELL PLAN ............................................................................ 95
4.3 THE NEW GEOSTEERING APPROACH .............................................................................. 97
4.4 THE DRILLING EXECUTION RESULTS OF NEW PRODUCER WELL .................................... 99
4.5 RESERVOIR SIMULATION PREDICTIONS OF THE PLANNED TRAJECTORY VS THE
EXECUTED WELL ................................................................................................................................. 101
4.5.1 Reservoir Model Grid Creation .................................................................................. 101
4.5.2 Comparative Analysis of Simulated Prediction Results between Original Planned
Trajectory vs Executed High Angle Well ........................................................................................ 106
5. CONCLUSION .............................................................................................................. 115
BIBLIOGRAPHY .................................................................................................................. 117
APPENDIX ............................................................................................................................ 120
ANNEXES ............................................................................................................................. 123
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FIGURES
Figure 1-1 – On the left, an advanced trajectory vs vertical well intercepting the same reservoir but with
different net pay interval. On the right, illustration of the drilling costs for vertical wells vs one horizontal
providing an equal oil production. ............................................................................................................... 2
Figure 1-2 – Two examples of high angle wells where Geosteering operation was used, optimizing the
well positioning and also increasing the total net pay interval. ................................................................... 3
Figure 1-3 – Illustration of well trajectories placed in different reservoir depths and the need to quantify
the productivity impacts created by these geometrical changes. .................................................................. 3
Figure 1-4 – Geometrical variations of advanced wells in 3 main categories. ............................................ 5
Figure 2-1 – The drilling of geometrical horizontal well consists of intercepting the specified targets, but
the geology is often different from originally modelled. ............................................................................... 8
Figure 2-2 – By adjusting the reservoir structural model (right panel), there is now a better matching
between the measured and the synthetic logs. .............................................................................................. 9
Figure 2-3 – Inversion of the bed boundary mapper tool detecting the distances of the conductive
boundaries present above and below the executed high angle well. .......................................................... 10
Figure 2-4 – Gas cap effect on oil recover as pressure function (west Texas black-oil)............................ 13
Figure 2-5 – Edge-water and bottom water drive mechanisms. ................................................................. 14
Figure 2-6 – Examples of encroachment angle to water influx in reservoir radial area. .......................... 16
Figure 2-7 – Geometrical illustration of the drainage areas of the vertical (upper part) and the horizontal
(lower panel) wells. .................................................................................................................................... 17
Figure 2-8 – Schematic of a fractured vertical well (x is the fracture half length). .................................. 18
f
Figure 2-9 – Vertical and horizontal well drainage areas for a given time. ............................................. 19
Figure 2-10 – A 3-D horizontal well problem solved by dividing into two 2-D approach. ........................ 24
Figure 2-11 – On the left side, advanced well and model with 3 phases and their fluid contacts. At the
right, simulated TVD locations and the production return. ....................................................................... 27
Figure 2-12 –Production costs of different crude oil types. ....................................................................... 28
Figure 2-13 – Illustration of the sections of ECLIPSE’s model. ................................................................ 35
Figure 2-14 – ECLIPSE’s input sections relating to the flow equation. .................................................... 36
Figure 2-15 – The numerical methods used in each reservoir simulator. .................................................. 37
Figure 2-16 – The geometry features available for each reservoir simulator. ........................................... 37
Figure 2-17 – Integration with other modelling software for each simulator. ........................................... 38
Figure 3-1 – Illustration of an anticline petroleum trap with different fluid contacts................................ 39
Figure 3-2 – 3D illustration of the anticline trap synthetic geological model. .......................................... 40
Figure 3-3 – Cross-section of geological model being intercepted by high angle well. ............................ 41
Figure 3-4 – 3D grid where volume growth factor is applied, providing a variable cell size from very
small near the wellbore to large scales around the grid edge. ................................................................... 42
Figure 3-5 – On the left, 3D synthetic reservoir model with pressure distribution. On the right, a cross-
section of the model illustrating a horizontal well near the top of reservoir. ............................................. 43
ix
Figure 3-6 – TVD depth positioning of horizontal wells against geological model. .................................. 44
Figure 3-7 – Lines direction of the fluid flow towards horizontal well near reservoir top. ....................... 45
Figure 3-8 – Lines direction of the fluid flow towards Well_3. .................................................................. 46
Figure 3-9 – Lines direction of the fluid flow towards Well_4. .................................................................. 46
Figure 3-10 – First year evolution of the production in Well_2. ................................................................ 47
Figure 3-11 – Pressure vs time plot (top panel) confirming high pressure depletion in all four wells.
Bottom panel shows the fast oil rate reduction for all trajectories. ........................................................... 48
Figure 3-12 – Cumulative oil production vs time plot for TVD positioning cases. .................................... 49
Figure 3-13 – Length variation of horizontal wells against geological model........................................... 50
Figure 3-14 – Plot of the downhole wellbore pressure vs time, with zoom when the pressure reached the
established lowest limit............................................................................................................................... 51
Figure 3-15 – Oil flow rate vs time plot for the length variation cases. ..................................................... 51
Figure 3-16 – Cumulative oil volume vs time plot for the length variation cases. ..................................... 52
Figure 3-17 – Field pressure vs time plot for the length variation cases. .................................................. 53
Figure 3-18 – Plot of cumulative volume and initial PI for length variation well cases. ........................... 53
Figure 3-19 – Sinusoidal variation of high angle wells against geological model. ................................... 54
Figure 3-20 – Cumulative oil volume vs time plot for the sinusoidal variation cases. ............................... 55
Figure 3-21 – Plot of cumulative oil volume and PI for the sinusoidal well cases. ................................... 56
Figure 3-22 – TVD positioning against geological model & Carter Tracy Aquifer. ................................. 57
Figure 3-23 – Time sequence of water coning for 8 yrs. simulated production in Well-1. ........................ 58
Figure 3-24 – Time when water cone intercepted each well after beginning production. ......................... 59
Figure 3-25 – Direction of flow from start of production until water flooding in Well-3. ......................... 59
Figure 3-26 – Oil flow rate vs time plot for the TVD positioning well cases with aquifer. ........................ 60
Figure 3-27 – Wellbore pressure vs time plot for TVD positioning cases with aquifer. ............................ 61
Figure 3-28 – Oil volume vs time for TVD variation with pressure adjustment. ........................................ 62
Figure 3-29 – Length variation against geological model & Carter Tracy Aquifer. ................................. 63
Figure 3-30 – Oil and water production rates distribution under water coning effect. ............................. 64
Figure 3-31 – Oil flow rate vs time plot for the length variation well cases with aquifer. ......................... 65
Figure 3-32 – Wellbore pressure vs time for length variation well cases with aquifer. ............................. 65
Figure 3-33 – Cumulative oil volume vs time plot for the length variation cases. ..................................... 67
Figure 3-34 – Oil volume vs time plot for the length variation with pressure adjustment. ........................ 68
Figure 3-35 – Sinusoidal variation against geological model & Carter Tracy Aquifer. ........................... 70
Figure 3-36 – Water influx into Well-3 (deepest TVD zone) after 5 production months. ........................... 71
Figure 3-37 – Cumulative oil volume vs time plot for the sinusoidal variation cases. ............................... 72
Figure 3-38 – Oil volume vs time plot for sinusoidal variation with pressure adjustment. ........................ 73
Figure 3-39 – Synthetic reservoir grid with gas-cap and oil zone distribution. ......................................... 75
Figure 3-40 – Direction of gas and oil flow lines in the reservoir with gas-cap. ....................................... 76
Figure 3-41 – Wells with length variation against reservoir grid with gas-cap. ....................................... 76
x