PHƯƠNG PHÁP ĐỊA CHẤN NGHIÊN CỨU ĐÁ CHỨA MÓNG PGS. NGUYỄN HUY NGỌC

CAC DOI DAP VO DOC CAC DUT GAY TRONG DA VOI D3-C1phCAC PHUONG PHAP NGHIEN CUU DA CHUA MONG:... CAC DOI DAP VO DOC CAC DUT GAY TRONG DA GRANITCAC PHUONG PHAP NGHIEN CUU DA CHUA MONG:... C

2 "From Seismic Interpretation to tectonic reconstruction" methodology and application to study the Pre-Tertiary fractured Basement reservoirs (Three hours lecture).

PHƯƠNG PHÁP ĐỊA CHẤN TRONG NGHIÊN CỨU ĐÁ

CHỨA MÓNG PTS: NGUYỄN HUY NGỌC (CHO CÁC KỸ SƯ ĐỊA CHẤT & ĐỊA VẬT LÝ DẦU KHÍ)

II- KHẢ NĂNG CỦA PHƯƠNG PHÁP ĐỊA CHẤN TRONG NGHIÊN CỨU ĐÁ CHỨA MÓNG:

A/ Mô Hình Địa Chất- Địa Chấn B/ Đặc điểm của trường sóng phản xạ

III- CÁC BIỆN PHÁP LÀM TĂNG CHẤT LƯỢNG TÀI LIỆU ĐỊA CHẤN PHẢN XẠ:

A/- Thu No

B/ Trong quá trình xử lý số liệu:

+ Các phương pháp hạn chế nhiễu + Các phương pháp làm tăng độ hội tụ của các sóng phản xạ

C/ Trong quá trình minh giải tài liệu:

+ Lọc nhiễu + Giải ngược địa chấn + Xác định độ ổn định hình dạng xung sóng + Phân tích phổ

IV- MINH GIẢI TÀI LIỆU ĐỊA CHẤN:

A/ Minh giải cấu trúc mặt móng B/ Minh giải đứt gẫy trong móng C/ Phát hiện và khoanh định các đới có triển vọng nứt nẻ cao

V- MỘT SỐ ỨNG DỤNG MINH HOẠ:

PHƯƠNG PHÁP ĐỊA CHẤN TRONG TỔ HỢP CÁC PHƯƠNG PHÁP NGHIÊN CỨU ĐÁ CHỨA

MÓNG:

CHIEU DAY DOI DAP VO CO THE DAT TOI VAI CHUC MET

CAC DOI DAP VO DOC CAC DUT GAY TRONG DA VOI D3-C1ph

CAC PHUONG PHAP NGHIEN CUU DA CHUA MONG:

CAC DOI DAP VO DOC CAC DUT GAY TRONG DA GRANIT

CAC DOI DAP VO DOC CAC DUT GAY TRONG DA GRANIT

CAC PHUONG PHAP NGHIEN CUU DA CHUA MONG:

CAC DOI DAP VO DOC CAC DUT GAY TRONG DA GRANIT

CAC PHUONG PHAP NGHIEN CUU DA CHUA MONG:

CAC DOI DAP VO DOC CAC DUT GAY TRONG DA EXTRUSIVE

CAC PHUONG PHAP NGHIEN CUU DA CHUA MONG:

• CAC DOI DAP VO DOC CAC DUT GAY TRONG DA

MONG CO CHIEU RONG THAY DOI TRONG MOT

PHAM VI KHA RONG ( TU HANG TRAM MET CHO DEN XANGTI THAM CHI MILIMET) GOC NGHIENG CUA

CAC DOI NAY CUNG THAY DOI TRONG PHAM VI

RONG.

• DE NGHIEN CUU CAC DOI NUT NE DO CAN XU

DUNG TO HOP NHIEU PHUONG PHAP KHAC NHAU, TRONG DO DIA CHAN LA MOT PHUONG PHAP

QUAN TRONG.

Cuu Long basin: Reflections from good fracture zones have been confirmed by well data

Well A

CAC PHUONG PHAP NGHIEN CUU DA CHUA MONG:

B-2X B-3X

B-4X

Typical Well Log Data For Fracture Zone Associated With Faults

Inside The Granite Basement

F7

Fracture systems are complex

Fracture zones accompanied

with NE-SW fault

Fracture zones accompanied with NE-SW fault

Outcrop: Mui Da – Phan Thiet Outcrop: Mui Ke Ga – Phan Thiet

Plan view Section view

PHOTO OF FRACTURES ASSOCIATED WITH FAULT CAC PHUONG PHAP NGHIEN CUU DA CHUA MONG:

PHOTO OF FRACTURES ASSOCIATED WITH FAULT

Fracture associated with reverse fault

with dip direction of 140Ð40

at Chau Thoi mountain.

Sigmoidal structure showing left lateral strike-slip of 850 striking fracture/fault

at Mui Da (Phan Thiet).

Fault and accompanied fractures (shear, tension) model

(after Mikhailov - 1982)

Section of accompanied fractures with normal fault

Section of accompanied fractures with reverse fault

Section of accompanied

fractures with normal fault

III THE MODEL OF FRACTURES ASSOCIATED WITH FAULT

CAC PHUONG PHAP NGHIEN CUU DA CHUA MONG:

THE MODEL OF TENSION & SHEAR FRACTURES

ASSOCIATED WITH NORMAL FAULT

Dip Angle > 45 o Dip Angle < 45 o

Dip angle > 45 o Dip angle = 45 o Dip angle < 45 o

THE MODEL OF TENSION & SHEAR FRACTURES

ASSOCIATED WITH REVERSE FAULT

CAC PHUONG PHAP NGHIEN CUU DA CHUA MONG:

THE MODEL OF TENSION & SHEAR FRACTURES ASSOCIATED

WITH STRIKE-SILP FAULT

Right-lateral

Left-lateral

Shear fracture accompanied with

50 striking (320Ð80) left lateral strike-slip fault

at Rưng La.

KHẢ NĂNG CỦA PHƯƠNG PHÁP

ĐỊA CHẤN TRONG NGHIÊN CỨU ĐÁ CHỨA MÓNG:

PHUONG PHAP DIA CHAN CO THE GIAI QUYET DUOC NHUNG NHIEM VU SAU TRONG VIEC NGHIEN CUU DA

MONG NUT NE:

• Ve ban do mat mong

• minh giai duoc cac dut gay cat mat mong va ben trong mong

• Phat hien va khoanh dinh duoc cac doi co trien vong nut ne cao doc cac dut gay

• Xac dinh duoc mot so dac diem cua cac doi co trien vong nut ne cao

Kha nang giai quyet cac nhiem vu nghien cuu da chua mong nut ne phu thuoc vao chat luong tai lieu va kinh nghiem cua nguoi minh giai

Fractured zone thickness distribution Typical Fracture Zone

Based On Well Log Data

CHARACTERS OF FRACTURE ZONES IN GRANITE BASEMENT

Cuu Long basin: Reflections from good fracture zones have been confirmed by well data

Well A

Cuu Long basin: Responses from fracture zone inside the granite basement

B/ Đặc điểm của trường sóng phản xạ

Su phu thuoc cua bien do song phan xa vao chieu day lop (Tuning curve)

Typical Well Log Data For Fracture Zone Associated With Faults

Inside The Granite Basement

F7

FAULTS INSIDE GRANITE BASEMENT

m

CAC DAC DIEM CUA SONG PHAN XA TU CAC DOI DAP VO DOC DUT GAY TRONG DA MONG:

• Bien do thap va khong on dinh (Ty so tin hieu / nhieu thap)

• Tan so thap (15- 25 Hz)

• Hinh dang xung khong on dinh

• Goc nghieng thuong lon

B/ Đặc điểm của trường sóng phản xạ

CÁC BIỆN PHÁP LÀM TĂNG CHẤT LƯỢNG TÀI LIỆU ĐỊA

CHẤN PHẢN XẠ:

TRONG QUÁ TRÌNH THU NO ĐỊA CHẤN:

The CL 99 survey was acquired by 3600 m streamer length, but the PCV 2002 survey was

3D seismic CL 99

3D seismic PCV 2002

3D seismic CL 99

TRONG QUÁ TRÌNH

XỬ LÝ TÀI LIỆU ĐỊA

CHẤN:

MUC DICH: LAM TANG CHAT LUONG CAC SONG PHAN

XA TU MAT MONG VA BEN TRONG MONG

• Cac phuong phap loc nhieu (Decon va Demultiple)

• Cong song (Phan tich toc do va muting)

• Dich chuyen dia chan

Isotropic PSDM

So sanh bang dia chan da dich chuyen bang Isotropic va Anisotropic PSDM

Anisotropic PSDM

Anisotropic PSDM

Top Horizon

C&D B1

In the Cuu long Basin horizontal velocity variation is observed in many sedimentary sequences (shallow sequence, B1, C, D and E sequences)

Basement Basement

Basement

PSTM PSDM

3D PSDM could significantly improve seismic imaging for both clastic and basement sections compared with 3D PSTM processing.

Inside Basement Velocity pick For Xline 2804

HSD 3D APSDM Seismic Data Reprocessing Depth Velocity Model along Xline 2592

Comparison Between 2007 & 2009 CBM Crossline 2630

HSD 3D APSDM Seismic Data Reprocessing

Comparison Between 2007 & 2009 CBM Crossline 2790

Comparison Between 2007 & 2009 CBM Time Slices 2500 &2700 ms

2009 CBM APSDM Reprocessing 2007 CBM APSDM Processing

2500 ms

TRONG QUÁ TRÌNH MINH GIẢI TÀI LIỆU

ĐỊA CHẤN:

MUC DICH: LAM TANG CHAT LUONG CAC SONG PHAN

XA TU MAT MONG VA BEN TRONG MONG, LAM TANG HIEN THI CUA CAC BAT DONG NHAT BEN TRONG MONG

• Cac phuong phap loc nhieu (Tan so va FK)

• Cong song (Near, Middle & Far offset Stack voi trong so)

• Giai nguoc dia chan (Seismic Inversion)

• Xu ly cac thuoc tinh lam tang hien thi bat dong nhat trong

mong (CCT, SAC, Spectral Decomposition)

Multiple noise level is reduced with offset

0-15 Degree Stacked 15-30 Degree Stacked 30-45 Degree Stacked

improve inside the basement reflections

Full offset stacked section Middle & Far offset stacked section

FK filtering could improve top and inside basement reflections

Middle & Far offset stacked section Middle & Far offset stacked section

basement reflections

SEISMIC INVERSION

Acoustic Impedance PDFs Of Granite Basement

Relative AI Section

IMPROVEMENT OF SEISMIC IMAGING FOR GRANITE BASEMENT BY POST-STACK

APPLICATION DURING INTERPRETATION PERIOD

Middle & Far offset stacked section with FK

filter

Full offset stacked section (The final 3D PSTM processing)

CBM PSDM Section CBM PSDM Section With Post-Stack Application

Improvement of Inside Basement Imaging in Xline 2605

Seismic 30-55 deg

Seismic 40-65 deg

Logs

Horizons

Constraints and Low Frequency

P-Impedance S-Impedance Density

RockTrace Simultaneous Inversion TM Workflow

12 ms (30 m) BELOW THE BASEMENT TOP 92 ms (230 m) BELOW THE BASEMENT TOP

Dip & azimuth Slice of P-Impedance & Vp/Vs at 2570 - 2582 ms

COHERENCE CUBE

TECHNOLOGY

CCT application for Inside the Basement:

Top Basement

SPETRAL DECOMPOSITION

Prospect B- Comparison between Normal Seismic (A) and Seismic Inverted (B) time slices at Inside Basement level

(A) (B)

inverted Seismic (B) time slices at 2040 ms (Inside Basement level)

(A) (B)

Prospect B- Comparison between Spec Decomp Of seismic inversion (A) and conventional seismic data (B) at 90 ms below the Basement top

Prospect B- Spec Decomp Of inverted seismic at 90 ms below the Basement top and fracture indication in drilled well

B-1X

B-2X B-3X

B-4X

MINH GIẢI TÀI LIỆU

ĐỊA CHẤN:

tectonic reconstruction” methodology to study

Pre-Tertiary fractured granite Basement reservoir in Cuu Long Basin South-east

Vietnam offshore

Dr Nguyen Huy Ngoc- Senior Geophysicist of Thang Long JOC

Dr Nguyen Quoc Quan- Deputy General Manager of Thang long JOC

MSc Hoang Ngoc Dong- Deputy Exploration Manager of Thang Long JOC

1 POSSIBILITY OF 3D SEISMIC IN STUDY OF FRACTURED GRANITE

BASEMENT RESERVOIRS:

• Structural Interpretation

• Fault Identification, Correlation & Clarification

• Prediction Of High Potential Fracture Zones Associated With

Interpreted Faults.

2 IMPOSSIBILITY OF 3D SEISMIC IN STUDY OF THE FRACTURED

GRANITE RESERVOIRS:

Necessary Of “ From Seismic Interpretation To Tectonic

Reconstruction” Methodology

Reconstruction Workflow

“from the scale of the plates

down to the scale of the

microscopic”

Cuu Long Basin &

Adjacent Continental Area

• Interpret block geophysical data & tie

back to adjacent blocks

• Analyse structural/ stratigraphic

features

• Define and construct the main

deformation phases

• Interpret prospect seismic data

• Define domains, fault systems

• Study prospect fault characterizations

• Reconstruct prospect tectonic stress

field

• Predict prospect fracture systems

LEVELS OF

“from Seismic Interpretation

to Tectonic Reconstruction

Block 15-02/01 Hai Su Den Structure Study Methodology for Basement Fractured Reservoirs

NW SE

Depth Slice at 3600m showing interpreted fault systems

& TECTONIC RECONSTRUCTION

Fault and accompanied fractures (shear, tension)

model (after Mikhailov - 1982)

Section of accompanied fractures with reverse fault

Section of accompanied fractures with normal fault

Section of accompanied

fractures with normal fault

• Seismic could image only Fractured zone associated with big faults Depends of Fault types the associated fractures could have different

direction and dip angle compared with fault plan.

• Faults have different characters and timing therefore they have

different role in HC accumulation.

PHILIPPINE PLATE

Paleo-South China Sea

Java

Study area

EURASIA PLATE

PACIFIC PLATE

INDIA-AUSTRALIA PLATE

Early Cenozoic Tectonic events occur in Southeastern boundary

of Eurasia plate (Robert Hall 2004)

BLOCK 15-02/01

0 25 50km E-W

Cuu Long Basin Dominant Structural Domains

Normal fault Reverse fault

Antiform axis Synform axis

Map of top E morphology

Antiform axis Synform axis

Map of top D morphology The N-S folds could be incorporated to a E-W compression phase after the

Block 15-02/01 Structural Reconstruction - Folding

• Reverse faults are

in red color

• Normal faults are

in black color

Block 15-02/01 Late Mesozoic-Cenozoic Main Deformation Phases

E

D C B1.1 B1.2

Opening the E-W shear system