petrophysical analysis of reservoir rock of kadanwari gas [autosaved]

Petrophysical Analysis Of Reservoir Rock Of Kadanwari

blockBy

Muhammad AliMS Geophysics

Project Supervisor: Prof. Dr. Mubarik AliProject Co-Supervisor: Mr. Abid Hussain

OUTLINE

1. INTRODUCTION OF THE STUDY AREA2. OBJECTIVE3. GEOLOGY, TECTONICS AND STRATIGRAPHY 4. DATABASE 5. METHODOLOGY6. RESULTS 7. CONCLUSIONS8. RECOMMENDATIONS9. ACKNOWLEDGEMENT

Location Map of Study Area

The assigned study area is geographically located at 27º 01′ 00′′ to 27º 10′ 00′′ N Latitude and 69º 05′ 00′′ to 69 º 22′ 00′′ E Longitude. District Khairpur, Sindh Province of Pakistan.

EXPLORATION HISTORY OF THE STUDY AREA

• The Kadanwari gas field discover in 1989 and brought on stream in 1995.• The operator started the field operation in may 1987 with acquisition

of 2D seismic.• The field was discover by the K-1 well which was drilled in September

1989.• The reservoir section at Kadanwari belong to the lower Goru sand

while the sealing is provided the upper Goru shaley sequence.

OBJECTIVE • Lithology identification.• Calculate of shale volume.• Determining the porosity of reservoirs.• Determining the water saturation and hydrocarbon.• Net pay thicknеss.• Borehole geometry.• Isochore map• Iso-porosity map • Iso-shale map • Iso-water saturation map• Net Pay map

Regional Structural Style

Modified from Aziz and Khan, 2003

Petroleum System

Source Rock Reservoir Rock Seal Rock Trap

Sembar Fm Lower Goru Fm Upper Goru Structural trap.

DATABASEThe data obtained for this research study were Well tops and open hole wireline logs of Kadanwari 01, 03, 10 and 11 wells including.

KADANWARI-01

KADANWARI-03

KADANWARI-10

KADANWARI-11

27.9.0 27.9.0

27.9.15 27.9.15

27.9.30 27.9.30

27.9.45 27.9.45

27.10.0 27.10.0

27.10.15 27.10.15

27.10.30 27.10.30

27.10.45 27.10.45

27.11.0 27.11.0

69.12.0

69.12.0

69.12.15

69.12.15

69.12.30

69.12.30

69.12.45

69.12.45

69.13.0

69.13.0

69.13.15

69.13.15

69.13.30

69.13.30

69.13.45

69.13.45

69.14.0

69.14.0

69.14.15

69.14.15

27.9.0 27.9.0

27.9.15 27.9.15

27.9.30 27.9.30

27.9.45 27.9.45

27.10.0 27.10.0

27.10.15 27.10.15

27.10.30 27.10.30

27.10.45 27.10.45

27.11.0 27.11.0

69.1

2.0

69.1

2.0

69.1

2.15

69.1

2.15

69.1

2.30

69.1

2.30

69.1

2.45

69.1

2.45

69.1

3.0

69.1

3.0

69.1

3.15

69.1

3.15

69.1

3.30

69.1

3.30

69.1

3.45

69.1

3.45

69.1

4.0

69.1

4.0

69.1

4.15

69.1

4.15

Well logs

GR logs

SP logs

Neutron-Density logs

Resistivity Logs

Sonic Log

GENERALIZED STRATIGRAPHY

Bore Hole Stratigraphy

Formation Age KADANWARI-01 KADANWARI-03 KADANWARI-10 KADANWARI-11

SIWALIK Pliocene 8 7.8 7.9 9

DRAZINDA

Eocene

306 240 310 325

PIRKOH 400 315 410 413

SIRKI 474 395 465 474

HABIB RAHI 544.5 484.5 553 561

GHAZIJ 680.5 621.5 695 705

SUI MAIN LIMESTONE 1279.5 1252 1320 1327

RANIKOT Palaeocene 1380 1373 1411 1415

UPPER GORU

cretaceous

1937.5 1997 1967 1948

LOWER GORU 2415 2496 3076 3084

SEMBAR 3797 NO DRLILL SECTION

PETROPHYSICAL TECHNIQUES(FORMULAS)

Shale Volume

• Gamma ray log used to calculate of shale volume• And also used to differentiate b/w shale and Non Shale• Gamma ray log scale range we used 0-250 API

Calculate Vsh from Gamma ray index

Effective Porosity • Effective porosity is calculated by sonic log.

• Use when density log is not presented, or when dеnsity log is affected by bad hole.

• Effective porosity = total porosity – non effective porosity (shale porosity)

• Sonic porosity equation.

• PHIS = (DT - DTma) ÷ (DTfld - DTma)

• Shale porosity equation.

• PHISSH = (DTshl - DTma) ÷ (DTfld - DTma)

• After calculated porosity from both equation than we computed effective porosity from;

• PHIE_S = (PHIS - Vshl * PHISSH)• Where

• PHIS = Sonic Porosity

• PHISSH = Shale Porosity

• PHIE_S = Effective Porosity

DTshl = interval transit time of shale

DTma = interval transit time of matrix

DT = interval transit time of formation

WATER SATURATION

• Water saturation is the amount of water in relation to the pore space only.

• Indonesian equation:

• Where • Sw = water saturation of formation • Rt = True resistivity (log reading)• Vsh = volume of shale• Rsh = resistivity of shale (log reading)

Rw = resistvity of formation water (computed from pickett plot) Фe = effectivity prosity (computed from sonic log)m = cementation factor (pickett plot)a = Archie constant (0.68 for sandstone)n = Saturation exponent

SATURATION HYDROCARBON

• Saturation HydrocarbonIn general HC saturation is denoted by Shc. Hydrocarbon Saturation is computed by using formula which is given below

Sg = 1-Swl (Schlumberger, 1974).

Swl = Water Saturation

• Bulk Volume of Water Bvw = Swi *effective porosity

Where

Swi = water saturation is uninvaded zone

Permeability From Log

Permeability should only be calculate from log when the formation is at irreducible water saturation . This condition can be determination using the Bulk volume water relationship.

BVW = Sw*effective porosity

When the Bulk volume water value are constant the interval is at irreducible saturation.

K = (79 * PHIE^3/SwIrr)^2 (For gas) K = (250 * PHIE^3/SwIrr)^2 (For oil)

Net PayNet pay is the portion of a resеrvoir from which hydrocrbons can be produced at economic proportions, given a particular production method (Lisa Dean 2007).

NET PAY = PHIE_S > PhiCutoff and SwI< SwCutoff and Vshl < VshCutoff

Cutoff valueCut off value are which I applied in own zone of interest:• Sw < 0. 5• Vshl < 0.35• Phie > 0.04

(Overall VSh in Lower Goru 35%)

PETROPHYSICAL INTERPRETATION

Rw is calculated by pickett plot

Rw Calculate From Pickett Plot

No. Well name Rw m a for s.st

1 Kadanwari well-01 0.30 1.80 0.68

2 Kadanwari well-03 0.33 1.82 0.68

3 Kadanwari well-10 0.22 1.76 0.68

4 Kadanwari well-11 0.27 1.80 0.68

Identifying the depth of mud cake and caving zone

Lithology identification using Gamma ray log

Detect the water bearing zone Detect the hydrocarbon bearing zone

Select the zone of interest and estimate the logging parameter for interpretation

Estimate of shale volume

Assessment the porosity From den/neutron and

sonic log

Determination of water from Indonesian

method

Bulk volume water Decision making for

next exploration work

Log Interpretation Methodology

Interpretation of Kadanwari Well-01

Interpretation of Kadanwari Well-01

Interpretation of Kadanwari Well-01

Interpretation of Kadanwari Well-01KAD WELL_01 TYPE TOP BASE THICKNESS PHIE PHIshl Vshl K Sw Sg BVW BVG

ZONE_3GROSS 3642 3645 3.1m

9.53% 34.33% 23.50% 0.78.6 29.13% 70.87% 0.73% 2.80%PAY 3643 3644 1m

ZONE_1GROSS 3510 3531 20.6m

8.55% 34.33% 11% 2.392 37.53% 62.47% 2.43% 7.45%PAY 3515 3529 8m

ZONE_2GROSS 3570 3585 15m

10.79% 34.33% 11% 4.77 20.12% 79.88% 1.56% 9.23%PAY 3572 3585 11m

ZONE_4GROSS 3669 3673 4m

8.48% 34.33% 19% 1.82 18.66% 81.34% 1.03% 7.45%PAY 3671 3673 2.2m

ZONE_5GROSS 3675 3681 6.4m

7.98% 34.33% 15% 1.2582 26.44% 73.56% 1.70% 6.28%PAY 3677 3678 1.7m

ZONE_6GROSS 3710 3745 35.3m

10.45% 34.33% 6.01% 259.47 18.58% 81.42% 1.74% 8.71%PAY 3710 3735 25.5m

ZONE_7GROSS 3752 3775 23.2m

7.81% 34.33% 10% 151.72 27.00% 73.00% 1.56% 6.25%PAY 3753 3775 7.68m

ZONE_8GROSS 3782 3797 15.3m

16.85% 34.33% 8% 25.596 20.54% 79.46% 15.33% 15.33%PAY 3782 3797 14.6m

The BVW (Product of porosity and water saturation) has been estimated from Indonesia model’s water saturation of gas sands which ranges from 0.024 to 0.07 respectively. Detailed results of BVW are shown in table. These values are indicating that the grain size of this reservoir sand is coarse to medium and very fine, respectively.

Interpretation of Kadanwari Well-03

Interpretation of Kadanwari Well-03

KAD WELL_03 TYPE TOP BASE THICKNESS PHIE PHIshl Vshl K Sw Sg BVW BVG HCPV

ZONE_1

GROSS 2885 2888 2.4m

11.13% 33.58% 16.22% 393.86 38.27% 61.73% 6.88% 6.88% 0.4911

PAY 2886 2888 2m

ZONE_2

GROSS 3346 3354 8.1m

7.32% 33.58% 12.92% 113.58 40.22% 59.78% 4.95% 4.95% 0.7823

PAY 3352 3354 2m

The BVW (Product of porosity and water saturation) has been estimated from Indonesia - model’s water saturation of gas sands which ranges from 0.04 to 0.07 respectively. Detailed results of BVW are shown in table. These values are indicating that the grain size of this reservoir sand is medium to fine and very fine, respectively.

Interpretation of Kadanwari Well-10

Interpretation of Kadanwari Well-10 and Well-11

Well-11 Type Top Base Thickness PHIE% PHIA% K Vshl% Sw % Sg % HCPV

Zone_1

GROSS 3351 3357 6.8m

14% 16.3% 78.6 14.8% 38% 61.9% 1.752538

PAY 3353 3555 2m

Well-11 Type Top Base Thickness PHIE% PHIA% K Vshl% Sw % Sg % HCPV

Zone_1

GROSS 3351 3357 6.8m

14% 16.3% 78.6 14.8% 38% 61.9% 1.752538

PAY 3353 3555 1.5m

Thickness Contour Map Of Zone

Subsurface Map

Zone follows SSE to NNW depositional strike/trend

Lateral Variation of Petrophysical Characteristics

• Shale Content Distribution Map

• Porosity Distribution Map

• Water Saturation Distribution map

• Hydrocarbon Saturation Distribution Map

• Net Pay Map

KADANWARI-01

0.104

KADANWARI-03

0.162

KADANWARI-10

0.122

KADANWARI-11

0.148

KADANWARI-01

0.086

KADANWARI-03

0.111

KADANWARI-10

0.191

KADANWARI-11

0.141

KADANWARI-01

0.375

KADANWARI-03

0.383

KADANWARI-10

0.130

KADANWARI-11

0.413

KADANWARI-01

0.625

KADANWARI-03

0.617

KADANWARI-10

0.870

KADANWARI-11

0.620

KADANWARI-01

8.23

KADANWARI-03

2.20

KADANWARI-10

2.20

KADANWARI-11

3.40

Conclusion • After importing Las files on petrophysical software quality control were done on all wells, Data for

density log and neutron log is not reliable as many zones affected from borehole irregularities (washout/breakout). The data quality is not too good so we have calculated porosity from sonic log.

• The derived formation resistivity factors (a, m) and Sw exponent (n) from graphical method of Pickett plot and formation water salinity had proved the reliability of the reflected petrophysical results. The computed porosity by Sonic-Raymer model was proved as more reliable model for the calculation of porosity for heterogeneous shaly sand reservoir where bad hole condition present. The Density-Neutron porosity model, was alternated in there not bad hole section present.

• The Indonesia model was used effectively to calculate water saturation for heterogeneous shaly sand reservoirs. This technique was used effectively and widely in petrophysical studies for the shaly sand reservoir in the Kadanwari Gas fields. B/c it gave more accurate water saturation values in the shalier zones.

• The petrophysical analysis of kadanwari gas field revealed that the field is a prolific gas zone. Many zones (well-01, well-03, wel-10 and well-11) were delineated and the petrophysical parameters of these reservoirs were carefully analysed. The analysis revealed that the reservoirs are good quality reservoir sands with average porosities ranging from 0.11 – 0.44, average water saturation ranging from 0.18 – 0.45 and hydrocarbon saturation averaging between 0.59 – 0.86. The net/gross of the reservoir is between 0.21 – 0.47. By contouring thickness trend is seems that the depositional strike at the time of deposition of Lower Goru is in S-N direction in General.

Suggestions for Further Work

• Due to limited data and the bad quality of available data the scope of study was restricted to

basic petro physical study of reservoir, so it is highly recommended to provide more data for

the detailed analysis.

• It also recommended to drilling more wells into / for the central part of the southwestern and

south-eastern part of the study area, In the vicinity of South Kadanwari-01 well, for more

hydrocarbon production from Lower Goru, for more favourable economic conditions. It also

suggested to avoiding drilling into/for the areas of high concentrations of water saturation

north-eastern and north-western part of the area. Because the shale content increase in lower

goru formation increase at north-eastern and noth-western side.

Acknowledgement

I would like to express my deepest gratitude to:

• Professor Dr. Mubarik Ali (Research Supervisor , HOD E & ES )• Mr. Abid Hussain ( Research Co-Supervisor , Senior Geologist at Ppl)