Progress and Achievements of Shale Gas Development in CNPC. Ailin Jia. Research Institute of Petroleum Exploration & Development, CNPC March, 2016

Transcription

1 Progress and Achievements of Shale Gas Development in CNPC Ailin Jia Research Institute of Petroleum Exploration & Development, CNPC March,

2 Introduction In recent 5 years, shale gas exploration and development in China has make great progress, especially in reservoir evaluation, productivity estimation and stimulation technologies. Both proved reserves and production rate has been growing rapidly, making larger-scale development possible. CNPC has actively promoted the commercial development for shale gas. The breakthrough of Well (Wei201) in 2010 initiated shale gas exploration and development in China. In early 2012, we began pilot study in Changning-Weiyuan and Zhaotong plays. After years of field experiment and practice, CNPC has innovated technique series for the development of shale gas reservoirs buried less than 3,500m. 2

3 Outlines 1. Current state of shale gas development in CNPC 2. Shale gas development technologies 3. Suggestions 3

4 (1) Longmaxi Formation with huge reserves is the main shale gas play in Sichuan Basin and surrounding regions. OGIP of Longmaxi Formation buried less than 4,000m is estimated to be over 7,500 billion cubic meters. About 4,000 billion cubic meters buried less than 3,500m Stratigraphy column of Sichuan Basin Shale of Longmaxi Formation Burial depth map of Longmaxi Formation, Sichuan Basin 4

5 (2) CNPC: Current favorable blocks 4 favorable blocks: Changning, Weiyuan, Fushun-Yongchuan, Zhaotong, with areas of 10,000 km 2 and OGIP of 4,500 billion cubic meters. 3 developing blocks: part of Changning, Weiyuan, Zhaotong, with areas of 2,400 km 2 and OGIP of 1,200 billion cubic meters. Weiyuan Weiyuan W202 W204 Fushun- Yongchuan Changning Changning Zhaotong Zhaotong YS108 N201 Favorable blocks of Longmaxi shale gas, Southern Sichuan Basin Developing blocks of Longmaxi shale gas, Southern Sichuan Basin 5

6 (3) Shale gas productivity of CNPC By 2015: 142 drilled wells, 98 producing wells with daily production of 8.6 million cubic meters, annual production of 1.3 billion cubic meters. The number of producing wells increases by 6 times and annual production increases by 7 times. NO. Block 1 2 Chang ning Weiyu an 3 Zhaoto ng NO. of Drilled Wells NO. of Producing Wells Daily Production (10 4 m 3 ) Annual Productivity (10 8 m 3 ) Production in 2015 (10 8 m 3 ) total Annual production( 10 8 m 3 ) NO. of Producing wells Annual production NO. of producing wells 6

7 (4) Shale gas prospect of CNPC for the 13 th Five-Year Plan period CNPC has set up a leading group to push forward shale gas exploration and development The productivity and annual production will increase more rapidly in the next five years. Establishment of Chongqing Shale Gas Co. Ltd. Officer of Sichuan province listens to the introduction of shale gas plan President of CNPC announces shale gas plan Establishment of Shale Gas Leading Group 7

8 Outlines 1. Current state of shale gas development in CNPC 2. Shale gas development technologies 3. Suggestions 8

9 Breakthrough in shale gas development technologies Shale gas development technologies 4 3 9

10 1. Geological Evaluation (1) Seismic survey 2D seismic survey for evaluation stage 3D seismic for production well site selection and trajectory design. inline1950 Geological map of well block N209 Well block N201 Well block N201 Inline1950 seismic migration Well block N201 3D stratigraphic surface Shale reservoir thickness Natural fracture prediction 10

11 (2) Stratigraphy correlation Three members: Longmaxi Formation divided into three members Three units: lower Longmaxi Member further divided into three units Three zones: lower unit with most favorable reservoirs divided into three zones Upper Longmaxi Upper Unit Upper Zone Carbonaceous shale 321m 102m Middle Longmaxi Middle Unit 21m Middle Zone Siliceous shale Lower Longmaxi Lower Unit Lower Zone Carbonaceous shale The characteristics of favorable reservoirs: high content of Uranium, a big gap between HSGR and HCGR curves, low density. 11

12 Favorable zones are stable in thickness throughout the region. Stratigraphy correlation of Changning-Zhaotong-Weiyuan Area 36.9km 164.4km 11.1km 18.7km Lower member Upper unit: average thickness 36m Middle unit: average thickness 45m Lower unit: average thickness 20m Weiyuan Changning Zhaotong 12

13 (3) Lithology facies Upper unit Mudstone with siltstone belts Middle unit Interbedding of calcareous mudstone and shale Lower unit Pay zone lithology Carbonaceous shale Siliceous shale Graptolite fossils 13

14 (4) Sweet spot distribution Longmaxi shale is deposited in a marine shelf environment, which makes the favorable reservoirs (sweet spots) distributed in a vast area Good seal condition leads to abnormal high pressure and high production rate 16.1km 11.7km 7.7km Upper Longmaxi Middle Longmaxi Lower Longmaxi 21.8m 20.8m 21.3m 19.7m 20.6m Favorable reservoirs Longmaxi Formation sedimentary model Stratigraphy correlation of Changning-Zhaotong area 14

15 (5) Key factors for sweet spots Geological factors : TOC, gas content, porosity, thickness and pressure Criterion for geological sweet spots geological sweet spots Factors Criterion TOC(%) >2 Thickness (m) >25 Gas content (m 3 /t) >2 Pressure coefficient >1.2 Porosity (%) >5 Sweet spots prediction based on 3D seismic interpretation 15

16 Engineering factors such as brittleness, Young modulus and Poisson ratio control the fracturing efficiency Factors Zhaotong Changning Weiyuan Structural background Stress state Axis and south wing of syncline Strike slipcompression Gentle syncline Twist compression Slope of palaeohigh Twist compression Vertical depth/m Thickness/m 31~35 30~46 24~40 TOC/% 2.1~ ~ ~3.3 Porosity/% 2.4~ ~ ~4.87 Gas content/m 3 /t 2.0~ ~ ~4.35 Stress coefficient Clay content/% ~45 Horizontal stress difference/mpa Young modulus/mpa 20~30 10~13 15~ Poisson ratio Britlleness 47~65 55~65 46~69 Natural fracture Highly fractured Highly fractured Highly fractured Well planning based on geological and engineering sweet spots 16

17 2. Fast Drilling of Horizontal Wells Optimization for casing program, PDC bits, gas factory drilling et. al. Drilling cycle shortened from 139 days to 69 days Water-based drilling fluid being tested, much cheaper and more environment-friendly Average drilling cycle/day Evaluation Period Well block N201 Productivity Construction Period Well block W202 Well block W204 Horizontal section drilling cycle/day Oil-based Water-based Drilling cycle of different period Drilling cycle using different drilling fluid 17

18 3. Multiple fracturing treatment Successful techniques including low-viscosity slick water, low-density proppant, soluble bridge plug and zipper-style fracturing 8-10 wells in one platform, fracturing operation cycle of one platform shortened to about 60 days Average well production increases 60%, from 100,000 m 3 /d to 160,000 m 3 /d Zipper-style fracturing Proppant density,1.0g/cm 3 H6-3 H6-5 H6-7 zipper-style fracturing: forming network of fractures High displacement: from couples of cubic meters to dozens of cubic meters Low-density proppant: reducing pollution Soluble bridge plug: no need for grinding, increasing wellbore diameter 18

19 4. Productivity evaluation (1) Gas well classification Five components synthetic classification method (FCSCM) Screening out 5 geological & engineering factors having influence production performance; h/ h C/ C β / β S / S ψ = ln η / η avg avg avg avg avg Well spacing Net pay thickness (h) Gas content (C) Criteria of five components synthetic classification method Proppant volume (β) Fluid volume concentration Horizontal range Discharge (η) Engineering fa cto rs OGIP Influence fa c to r o n ra te & E U R Correlated with R eservoir ch aracteristics Porosity Pressure coefficient (S) Permeability Correlation between EUR and screened five components Types ψ Average rate in 1 st year (10,000m 3 /d) EUR (10,000m 3 ) I ,880 II 1.36~ ~7.5 7,220~9,880 III ,220 19

20 (2) Production performance evaluation At equilibrium, gas molecules are distributed throughout porous media Free gas: existing as compressed gas in the pores, proportion by 60~70% Adsorbed gas: covering the surface of the kerogen material Gas flowing process is divided into three sequences: Gas desorption from matrix bulk to microscale fractures Gas flowing from microscale to macroscale fractures Gas flowing from macroscale fractures to main hydraulic fractures and well hole Macro fractures of formations Flow mechanism of shale gas reservoirs Production performance model of horizontal well 20

21 Results of production performance analysis: 预测单井最终累积产量 EUR (10,000m 3 ( ) 万方 ) Average OGIP per well is about 100 million cubic meters Average EUR amounts to 75 million cubic meters for each well. Average production rate in 1 st year reaches 64,000m 3 /d 长宁 H3-4 长宁 H3-5 长宁 H2-5 长宁 H3-2 YS108H1-3 长宁 H2-7 宁 201-H YS108H1-5 长宁 H2-2 长宁 H2-6 长宁 H3-6 威 204H1-2 长宁 H2-4 长宁 H3-1 威 204H1-3 威 204 平长宁 H3-3 长宁 H2-1 长宁 H2-3 威 205 平平均 Average production rate in 1 第一年平均产量 st year (10,000m ( 万方 3 /d) ) 长宁 H3-4 长宁 H3-5 长宁 H2-5 YS108H1-3 长宁 H2-7 *20 wells with over 1 year history are analyzed 宁 201-H1 长宁 H3-2 YS108H1-5 长宁 H2-2 长宁 H2-6 长宁 H3-6 威 长宁 H2-4 长宁 H3-1 威 威 204 平 长宁 H3-3 长宁 H2-1 长宁 H2-3 威 205 平 6.4 平均 EUR evaluation for gas wells which has been producing over 1 year. Average production rate in 1 st year for gas wells which has been producing over 1 year. 21

22 5. Optimization of development parameters (1) Drilling target Best drilling target : the low member of Longmaxi Fm. the lower member possesses the best reservoir characteristics Geology reason: middle zone higher brittleness, indicating easy to be fractured located in the middle of high quality layer higher EUR prospected lower zone highest reserve abundance Previous target 102m Upper unit Middle unit Current target 21m Upper zone Middle zone higher initial production rate Lower unit lower zone Drilling target in low member of Longmaxi Fm. 22

23 (2) Horizontal length and fracture parameters Horizontal length: m Fracture stages: Cluster spacing: 20-30m Alternative fracturing treatment between adjacent wells. Through optimization (a) Pressure distribution at later stage of producing with current fracture parameters (b) Pressure distribution at later stage of producing with optimized fracture parameters Two scenarios of multiple fractured horizontal well placement Comparison of cumulative gas production under two scenarios 23

24 (3) Well spacing Well spacing can be reduced from m to m Well density increases by 30% Recovery factor enhances from 25% to 35%. Well spacing of shale gas field in China and U.S.A Barnett Haynesville Marcellus Eagle Ford CNPC Horizontal length (m) Well spacing (km 2 ) 0.24~ ~ ~ ~ ~1.1 Average well spacing (km 2 ) Fracture half-length (m) Average well distance (m) ~ ~ ~ ~500 24

25 (4) Production operation optimization At core scale, shale and tight sand stone samples are both sensitive to stress. At reservoir scale, formation structure is the main controlling factor. Supporting from surrounding wall rock results in poor stress sensitivity of pay zone. Lack of supporting, thin-bedded shale reservoir shows obvious stress sensitivity. Tight gas reservoir Shale gas reservoir K/K Core analysis in lab 基质人工支撑裂缝 Fracture filled with proppant 有效应力 Stress (MPa) (MPa) Experimental data on stress sensitivity of tight sands K/K Matrix Matrix 基质 ( 含微裂缝 ) 人工支撑裂缝 Fracture filled with proppant 有效压力 Stress (MPa) (MPa) Experimental data on stress sensitivity of shale Nonpermeable layer Lenticular sands fracture Thin bedded shale layer reservoir scale Tight gas sand reservoir fracture Shale gas reservoir Pressure drop Formation deformation Pressure drop 25

26 To avoid steep decline of production rate at early stage EUR of single well has potential to increase by 30% Well name Vertical depth(m) Target formation Horizontal length(m) Stages EUR(10 6 m 3 ) Well Middle zone, S 1 l Well Middle zone, S 1 l Production rate(10 thousand Production rate(10 thousand m3/day) m3/day) Daily 日产气 production rates 油压 Tubing pressure Well million m 3 /MPa 4.5 million m 3 /MPa 0 7/18/2012 2/3/2013 8/22/2013 3/10/2014 9/26/2014 4/14/ /31/ 日产气 Daily production rates 套压 Casing pressure Well million m 3 /MPa /13/2015 3/25/2015 5/4/2015 6/13/2015 7/23/2015 9/1/ /11/ /20/ Tubing pressure (MPa) Casing pressure (MPa) 26

27 Outlines 1. Current state of shale gas development in CNPC 2. Shale gas development technologies 3. Suggestions 27

28 Suggestions Geology conditions varying in different regions such as depth, gas content, pressure coefficient, faults etc., it is necessary to improve understanding and find out more potential targets. Weiyuan Fushun- Yongchuan Changning Zhaotong Favorable blocks of Longmaxi shale gas, Southern Sichuan Basin 28

29 Suggestions Drilling, completion & fracturing techniques need to be further studied as for the formation buried more than 3500m. >3500m Burial depth of Longmaxi Formation in Weiyuan Block 29

30 Suggestions The relation between production performance and operation condition needs to be analyzed, due to limited production data. 4 产气量 m 3 Production rate (10 /d) 4 m 3 /d) ( 日产气实测值 Limited production data P10 leads 预测 to probabilistic forecase P50 预测 P90 预测 EUR P10 =8234 万方 Probabilistic EUR forecast P50 = 万方 Probabilistic EUR forecast P90 = 万方 Probabilistic forecast 3 Production rate (10 4 m 3 /d) More cumulative production in the condition of limited pressure by 30% Open pressure 放压日产 Limited pressure 控压日产放压累产 Open pressure 控压累产 Limited pressure Cumulative production (10 4 m 3 ) /6/7 2016/6/7 2017/6/7 2018/6/7 2019/6/7 2020/6/7 2021/6/7 生产日期 Time (day) Probabilistic production forecast 生产时间 Time (day) 天 Comparison between open pressure and limited pressure condition in the case of stress sensitivity 30

31 Suggestions Designed horizontal well & fracturing parameters need to be further evaluated, including target location, well spacing, effective fracture length, height etc. PI PI i I y <I yopt I y =I yopt I y >I yopt 系列 1 系列 2 系列 i 4 nf=7 n f nf=5 n f nf=3 n f Reserves(SRV) Drilling pad OGIP I y Well spacing optimization Fracture parameters optimization 31

32 Thanks for your attention! 32