Study on Improving Recovery Factor by Horizontal Wells for Ultra Heavy oil Reservoirs in the Western Depression of Liaohe Basin

摘要

After almost 40 years of exploration and development, Liaohe Oilfield has discovered proved heavy oil in place of over 1 billion tons, produced heavy oil reserves of about 0.74 billion tons, and the heavy oil production of Liaohe Oilfield has accounted for over 60％ of its total production. Although heavy oil reservoirs have been put into full-scale development owing to the advances in cyclic steam stimulation technology and production practice, the cyclic oil-steam ratio has been near the economic limit in later cycles of steam stimulation, the reserves controlled by single vertical wells are low, the well conditions deteriorate, edge and bottom encroaches, stable production is difficult to achieve, steam conformance is limited, and the recovery percent of reserves is low In order to improve the development efficiency of heavy oil reservoirs, a substantial amount of investigations has been conducted for horizontal well drilling technology and application at home and abroad, the research project of adjusting, planning and developing heavy oil reservoirs by using horizontal wells has been proposed, and the study mainly involves 3 aspects: (1) The study of residual oil distribution and the applied experiment of reservoir engineering design with horizontal wells for Liaohe heavy oil reservoirs. The target canes are technically analyzed in respects of fame structure description, reservoir description, sedimentaryfacies description, fluid property analysis, and well production conditions by using testing techniques of reservoir performance, fme interpretation of geophysical logging, reservoir engineering calculation with produced boundary and without grid, and numerical simulation. The areas rich in residual oil after many cycles of steam stimulation have been determined, a model of residual oil saturation between vertical wells has been built, and research trials of adjusting development program have been conducted for typical old heavy oil reservoirs with edge and bottom water and thin layers by using horizontal well technology. (2) Study on horizontal well drilling technology for heavy oil reservoirs in Liaohe Oilfield. In order to implement scale application of horizontal well technology to heavy oil reservoirs, meticulous study has been conducted for geological engineering design of single horizontal well in respects of reservoir distribution prediction, pilot hole optimization, well path optimization, hole structure optimization and completion optimization in accordance with the uncertainties of formation caving and lost circulation in heavy oil reservoirs. Dynamic tracking has been carried out on site to realized safe drilling. (3) Study on steam injection technique for horizontal section of horizontal wells in Liaohe Oilfield. In accordance with the characteristics of deep well, heavy oil and long horizontal section, the parameters of steam injection are optimized, the methods of steam injection and heat insulation are studied, thus improved steam injection and heat insulation effects, realized even injection in heavy oil reservoirs, and laid basis for improving recovery factor. The following 4 cognitions have been acquired through the studies above: (1)Except the low pressure around wells experienced many cycles of steam stimulation, the other areas still maintain at initial pressure; the temperature increases differently at30～50m from the well, and most of the rest part still keeps at original reservoir temperature; oil saturation between wells is basically about 65％ of the initial saturation; oil viscosity reduces a lot at about Some to around well bore, and keeps almost at the original level beyond; (2) the structural high is less affected by bottom water coning and has rich remaining oil; the structure low is severely watered out as affected by both edge and bottom water. Horizontal well can effectively slow down the speed of edge and bottom water advancing, and improve the producing degree of reservoirs. (3) Gesturing is a guarantee for successful drilling of horizontal wells. For drilling in reservoirs with complex geological conditions, developed faults, big structural relief and drastic lateral change of reservoirs, gesturing must be applied. Gesturing performs real time follow-up according to the interpretation chart of the corresponding relationship between deviation angles and cutting lag time during build-up process, as well as the interpretation chart of the correspondence between different drilling assembly (screw drilling or rotary drilling) and litho logy, rig time and drill pressure in different formations. It improves the accuracy of geologic tracking and ensures reservoir encountering rate. (4) The result of economic evaluation analysis indicates that, the average single horizontal well investment is2.0～2.5 times of that of the vertical well; the average single well production is 2～4times of that of the vertical; the average annual operation cost of single horizontal well is 0.5～0.66 time of that of the vertical; within the evaluation period, the average net present value of single horizontal wells is 23.8 times of that of the verti Horizontal well is an economic way for developing heavy oil reservoirs and achieve better economic benefits This research study has obtained technical achievements in 4 aspects: (1) Drilling analysis and control technology for improving well path accuracy. The relationship chart of different drilling assembly (screw drilling or rotary drilling) corresponding to litho logy, rig time and drill pressure in different formations has been established according to lab established interpretation chart of the corresponding relationship between deviation angles and cutting lag time during build-up process. Real time tracking has been conducted during horizontal well drilling, and the accuracy of well path tracking has been greatly improved. (2) Horizontal well drilling assembly has been optimized in accordance with the features of unconsolidated heavy oil reservoirs for safe and fast drilling, the capacity of cutting-carrying in horizontal section has been improved, and the drilling fluid system of whole cleaning has been developed for horizontal well. Special tools for horizontal well has been use tonsure that the lineal contact force between casing and sidewall distributes in uniformly, slightly and gradually increasing pattern without abrupt change of peak value, and the maximum stress is less than half of the limit stress. Well path design is optimized to form gradual building up; the drilling fluid system of high temperature resistance and lost circulation prevention suitable to high temperature voided protection thus ensured safe drilling and improved drilling speed. (3) J-shape horizontal well drilling technology has been developed for the problem of horizontal section cementation in heavy oil reservoirs with top water. For heavy ail reservoirs with top water, where the build-up section is unconsolidated glutamate and cementing quality is poor, a drilling method of reverse drilling from the stable mudstone below to enter the reservoir has been developed, i.e., J-shape horizontal well, thus improved cementing quality in highly deviated section. (4) The technology of reservoir engineering with horizontal wells has been developed for overall adjustment of old oilfield development after many cycles of steam stimulation. Geological model and grid system are constructed for pilot area through numerical simulation; the conformances of pressure and temperature are observed through basic data analysis and history match; the distribution of residual oil saturation is determined; and the lateral and vertical location of horizontal well, the optimum length of horizontal section, the optimum steam injection parameters are selected according to residual oil distribution.

目录

英文文摘

0 Introduction

0.1 The Purpose and Significance of Thesis Topics

0.2 The Main Research Scope and Technical Route

0.2.1 The main research scope

0.2.2 Technical Route

0.3 Research Status at Home and Abroad

0.3.1 Present situation of heavy oil development technology in the world

0.3.2 Horizontal Well Drilling Technology Study and Application Status at Home and Abroad

0.3.3 Research Status of Residual oil at Home and Abroad.

0.3.4 Current Situation of Horizontal Well Application in Heavy Oil Reservoir Development at Home and Abroad

0.4 Work Completed

0.5 Innovations

1 Heavy Oil Reservoir Characteristics in the Western Depression of Liaohe Basin

1.1 Characteristics of Heavy Oil Reservoirs in Liaohe Oilfield

1.2 Tectonic Characteristics of Heavy Oil Reservoirs in Liaohe Oilfield

1.3 Petrophysical Properties and Classification of Heavy Oils in Liaohe Oilfield

2 Study on Residual Heavy Oil Distribution in the Western Depression of Liaohe Basin

2.1 Basic Characteristics of Cyclic Steam stimulation for Liaohe Heavy Oil

2.1.1 Production

2.1.2 Cyclic Ratio of Water Produced to Steam Injected(Qw/Qs)

2.1.3 Cyclic Oil Steam Ratio

2.1.4 Production/Unit Pressure drop

2.2 Study and Application of the Rule of Residual Oil Distribution in Bottom Water Heavy Oil Reservoirs

2.2.1 Main Characteristics of Bottom Water Heavy Oil Reservoirs

2.2.2 Basic Conditions of Block Leng 41

2.2.3 Construction of Reservoir Numerical Simulation Model

2.2.4 Reservoir Engineering Design of Well Leng 41-Ping 1

2.2.5 Index Prediction of Well Leng 41-Ping 1

2.2.6 Result Analysis of Bottom Water Heavy Oil Reservoir Development by Horizontal Wells

2.2.7 Cognitions of Bottom Water Heavy Oil Reservoir Development by Horizontal Wells

2.3 Study and Application of Residual Oil Distribution in Heavy Oil Reservoirs with Edge Water

2.3.1 Main Characteristics of Heavy Oil Reservoirs with Edge Water

2.3.2 Basic Conditions of Block Huan 127

2.3.3 Construction of Reservoir Numerical Simulation Model

2.3.4 Reservoir Engineering Design of Well Huan 127-Ping 1

2.3.5 Index Prediction of Well Huan 127-Ping 1

2.3.6 Result Analysis of Edge Water Heavy Oil Reservoir Development by Horizontal Wells

2.3.7 Cognitions of Edge Water Heavy Oil Reservoir Development by Horizontal well

2.4 Study on Application of Horizontal Well for Effective Development of Marginal Thin Heavy Oil Reservoir

2.4.1 Features of Thin Heavy Oil Reservoir

2.4.2 Reservolr Geological Characteristics of Block Wa70

2.4.3 Horizontal Well Reservoir Engineering Design for Block Wa70

2.4.4 Horizontal Well Development Deployment and Parameter Prediction for Block Wa70

2.4.5 Horizontal Well Application Results in Developing Thin Heavy Oil reservoir

2.4.6 Understandings Gained from Developing Thin Heavy Oil Reservoir with Horizontal Well

3 Study on Horizontal Well Drilling Technique in Unconsolidated Heavy Oil Reservoir

3.1 Horizontal Well Drilling Geology Optimization

3.2 Horizontal well Geosteering Tracking Technology

3.2.1 Cutting Lag Time Calibration of Different Sections of Horizontal Well During Mud Logging

3.2.2 Geological Steering by ROP Changes in Different Lithology

3.2.3 Adjusting Well Trajectory Well Logging Data

3.2.4 Calibrating Predicted Profile by Actual Drilling Lithology Data

3.2.5 Pilot Hole Control and LWD Geosteering

3.3 Safe Drilling Techniques in Unconsolidated Heavy Oil Reservoirs.

3.3.1 Difficulties in drilling Horizontal Well in Heavy Oil Reservoirs

3.3.2 3D Anti-Collision and Avoiding Adjacent Casing Techniques

3.3.3 Drilling with Composite Steering Drill Tool and Precise Trajectory Control Technique

3.3.4 Measures for Ensuring Smooth Running of Large Size Casing

3.3.5 Sticking Condition Analysis and Precautions for Drilling Horizontal Well in Heavy Oil Reservoir

3.3.6 Hole Cleaning Technique For Horizontal Well Drilling

3.3.7 Drilling Result

3.4 Horizontal Well Drilling Fluid Technology for Heavy Oil Reservoir

3.4.1 Determination of Horizontal Well Drilling Fluid for Shallow Heavy Oil Reservoir:Taking Du 84 Block as an Example

3.4.2 Determination of Drilling Fluid System for Heavy Oil Horizontal Well:Taking Lengjia Oilfield as an Example

3.4.3 Field Application

4 Steam Injection Technology and Application of Horizontal Wells for Ultra Heavy Oil Reservoirs in the Western Depression of Liaohe Basin

4.1 Technical Requirements

4.2 Steam Injection Technology and Application of Horizontal Well for Medium-Deep Heavy Oil

4.2.1 Steam Injection Technology in Horizontal Well for Medium-Deep Heavy Oil

4.2.2 Application Case of Steam Injection Technology of Horizontal Well Medium-Deep Heavy Oil

4.3 Dual String Injection Technology and Application in Horizontal Well

4.3.1 Dual String Injection Technology in Horizontal Well

4.3.2 Application Case of Dual String Injection Technology in Horizontal Well

4.4 Multiple Points Steam Injection Technology and Application in Horizontal Well

4.4.1 Multiple Points Steam Injection Technology in Horizontal Well

4.4.2 Application Case of Multiple Steam Injection Technology in Horizontal Well

5 Test of Horizontal Well Steam Assisted Gravity Drainage

5.1 Technical Principle of Horizontal Well Steam Assisted Gravity Drainage

5.2 Technical Limit for Horizontal SAGD Design

5.3 Deployment Case of Combined SAGD with Vertical and Horizontal Wells to Recover Super Heavy Oil Reservoir

5.3.1 Development Status of SAGD Test Area

5.3.2 Optimized Design Study on Horizontal SAGD Program.

5.3.3 Analysis of Test Effect of Horizontal SAGD

5.4 Understanding on Development of Super Heavy Oil Reservoir with Horizontal Well SAGD

6 Economic Evaluation and Analysis of Horizontal Well Production Technology for Ultra Hheavy Oil Reservoirs in the Western Depression of Liaohe Basin

6.1 Analysis of Horizontal Well Investment

6.2 Analysis of Economic Benefit of Horizontal Well

7 Conclusion and Suggestions

7.1 Conclusion

7.2 Suggestions

References

Acknowledgements

Resume

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