Development Drilling of 31 Wells and establishment of...

Pre-Feasibility Report

On

Development Drilling of 31 Wells and

establishment of Early Production System

(one) at Nagayalanka in the Onland NELP-V

Block KG-ONN-2003/1, Andhra Pradesh

2014

Oil and Natural Gas Corporation Ltd. (A Govt. of India Enterprise),

Rajahmundry Asset Rajahmundry-533106

Development Drilling of 31 Wells and establishment of Early Production System (one) at Nagayalanka

Asset HSE, Rajahmundry Asset

Pre-Feasibility Report On

Development Drilling of 31 Wells and establishment

of Early Production System (one) at Nagayalanka in

the Onland NELP-V Block KG-ONN-2003/1, Andhra

Pradesh

1.0 Introduction

The onland Block KG-ONN-2003/1 was awarded to the Consortium of Oil and Natural

Gas Corporation Limited (ONGC), Cairn Energy India PTY Limited (CEIL) and Cairn

Exploration (No.4) Limited (CE4L) under NELP Round-V in 2005. Participating Interests

(PI) were 51%, 24% and 25% respectively with CEIL being the Operator in the Block.

PEL for the Block was granted on 08.02.2007. In 2008, CE4L assigned its entire PI to

Cairn India Limited (CIL). Subsequently, CEIL also assigned its entire PI to CIL and

also obtained approval for transfer of Operatorship in favor of CIL in 2012. Currently,

the consortium partners in the Block are ONGC and CIL with PI of 51% and 49%

respectively. ONGC is the Operator during Development and Production Phase

w.e.f. 09.07.2014.

The Block area is geographically located in the southern part of Krishna-Godavari Basin,

near the mouth of the Krishna River and falls mostly within the Krishna District and a

small part within Guntur District in the State of Andhra Pradesh.

The Minimum Work Programme (MWP) of the Block during Exploration Phase of

7 years (Phase-I of 3 years, Phase-II and III each of 2 years duration) entailed 2D and 3D

seismic data acquisition, processing & interpretation, geochemical sampling &

study and drilling of eight Exploratory Wells (5 in Phase-I, 1 in Phase-II and 2 in

Phase-III). The MWP for the Exploration Phase has been completed and two commercial

hydrocarbon pays viz. Raghavapuram Pay and Gollapalli Pay have discovered during

Phase-I and Phase-II activity respectively. The commerciality of these discovered oil and

gas reserves has been further substantiated through an appraisal work programme

(Appraisal Phase) wherein drilling and testing/assessment of two appraisal wells were

completed. In view of the discoveries made, the Block entered Appraisal Phase (without

entering Phase-III of the Exploration Phase).

The discoveries have been reported to DGH/MoPNG through Declaration of

Commerciality (DoC) reports submitted on 26.03.2012 and 29.11.2013 respectively for

the Raghavapuram and Gollapalli pays. The DoCs have been reviewed by GoI on

09.07.2014 and Field Development Plan (FDP) is under preparation.

The two pays viz. Gollapalli and Raghavapuram, occurring within close temporal

proximity and having similar spatial distribution of prospective areas, will be developed

jointly, through an integrated approach, for robust techno-economic viability.



Table 1: Project Summary

2.0 Details of the Block KG-ONN-2003/1

The awarded Block KG-ONN-2003/1 encompasses an area of 1697 sq km and located

in the southern part of Krishna-Godavari Basin, near the mouth of the River Krishna. At

the end of Phase-I activity, an area of 435 sq km was relinquished; on completion of

Phase-II activity another 947 sq km was relinquished. The remaining area of 315 sq km

(Discovery area) has been retained for development drilling and production activities.

ONGC is the Operator for the Block w.e.f. 09.07.2014 for the Development and

Production Phase.

Block Details:

Block Name : KG-ONN-2003/1

NELP Round : V

JV Partners : ONGC 51%, CIL 49%

Operator for the Block : ONGC (Development & Production Phase)

PSC signed on : 23.09.2005

Effective Date of PEL : 08.02.2007

Development Area : 315 sq km (Discovery area)

2.1 Geological Setting

The Krishna-Godavari Basin is a NE-SW trending pericratonic basin situated on the

eastern continental margin of India. The KG-ONN-2003/1 Block is located in the West

Godavari sub-basin of this Krishna-Godavari Basin and geographically in close proximity

to the mouth of the River Krishna. Structurally, the Block area contains a number of

rotated fault blocks separated by half-grabens which are arranged in an en-echelon

manner and offset by major cross-faults.

Stratigraphically, the Gondwana sediments of Carboniferous-Permian-Triassic age rest

unconformably on the Pre-Cambrian Archaean basement. The Late Jurassic-Early

Cretaceous sequence began with the sand-dominated Gollapalli Formation in the West

Godavari sub-basin. The Gollapalli Formation comprises of a series of stacked

micaceous and gritty sandstones. The overlying Raghavapuram Shale represents the

first significant marine transgression. This shale thins westwards and onto the structural

Name of the Project Development drilling of 31 wells and establishment of Early Production System (one) at Nagayalanka in the onland NELP-V Block KG-ONN-2003/1, Andhra Pradesh

Block Area 315 sq km (Discovery area)

Geographical Location Nagayalanka area (falls mostly in Krishna District and

small part in Guntur District of Andhra Pradesh)

No. of Wells 31 Nos

Target Pay Horizons 2 (Gollapalli and Raghavapuram)

Hydrocarbon Reserves In-place: OIIP: 292 MMbbl; GIIP: 524 BCF

Total cost of the Project Rs. 6804.00 Crores

Details of the Locations and

Location map

Coordinates of Discovery area at Table 3,

(Location of individual wells to be finalized)



highs in the basin, where significant sandstones, including the Raghavapuram

Sandstone, have developed. Bantumilli and Tirupathi Sandstones are of Late

Cretaceous age. These are overlain by the Tertiary sediments.

3.0 Exploration Activities and Data Acquisition

During the pre-NELP Era, three wells were drilled by ONGC in Nagayalanka area. The

wells, however, were all dry. Consequent to the award of the Block KG-ONN-2003/1 to

ONGC-CIL consortium during NELP-V, Exploration Phase work is completed.

3.1 Work Done in Exploration Phase

During the Exploration Phase, 2D and 3D seismic data acquisition, processing &

interpretation, geochemical sampling & study and exploratory drilling were carried out. 5

wells were drilled during Phase-I, 1 well during Phase-II and 2 wells during the Appraisal

Phase. Summary of work done is mentioned under Table 2.

Table 2 Work done in the Block KG-ONN-2003/1 during each Phase

Phase Actual Work Done Remarks

Pre-NELP wells

Drilled 3 wells – Bubbarlanka-1,

Bhavadevarapalli-1,

Mantripalem-1

Wells dry and abandoned

Phase-I

a) API of 523 LKM 2D seismic

data

b) Reprocessed 1697 LKM 2D

seismic data

c) API of 255 SKM 3D seismic

data

d) Collected 500 Geochemical

samples and studied

e) Drilled 5 Exploratory wells –

Nagaram-1, Daliparu-1,

Lankapalle-1, Krishna-1,

Nagayalanka-1/

Nagayalanka-1z

a) Nagayalanka-1z –

Raghavapuram Discovery

b) Other 4 wells dry and

abandoned

c) Relinquished 435 sq km area

Phase-II

Appraisal Phase

a) Reprocessed 328 LKM 2D

seismic data

b) Reprocessed 255 SKM 3D

PSDM data

c) Drilled 1 Exploratory well –

Nagayalanka-SE-1

a) Drilled 2 appraisal wells –

Nagayalanka-1z-ST,

Nagayalanka-NW-1z

a) Nagayalanka-SE-1 – Gollapalli

Discovery

b) Identified and retained 315 sq

km area as the Nagayalanka

Discovery area. Relinquished

remaining 947 sq km area

a) Nagayalanka-1z-ST produced

oil and gas from Gollapalli and

Raghavapuram pay sands.

Extended well testing (EWT)

also carried out.

b) Other well dry and abandoned



Phase-III - Phase-III Not entered

4.0 Hydrocarbon Discoveries

Raghavapuram Sandstone and Gollapalli Sandstone are the two discovered

hydrocarbon bearing pay zones in the block which have been identified during Phase-I

and Phase-II activity respectively. These two potential reservoirs occur within the

Cretaceous sequence.

Submission of Declaration of Commerciality (DoC) Report –

i) DoC for Nagyalanka-1z Discovery (Raghavapuram Pay) submitted on 26.03.2012;

ii) DoC for Nagayalanka-SE-1 Discovery (Gollapalli Pay) submitted on 29.11.2013.

The DoCs have been reviewed by GoI on 09.07.2014 and Field Development Plan

(FDP) is under preparation.

5.0 Project Description

5.1 Description of Contract Area

Project Region Block Title Block Area

(sq km)

Remarks

Onland area mainly in

Krishna District and small

part in Guntur District of

Andhra Pradesh

KG-ONN-2003/1

315 Table 3 for

coordinates of the

Discovery area for

development drilling

Table 3 coordinates of the Discovery Area (315 sq km)

Point

UTM44N Projection GCS WGS1984

X Y Longitude Latitude

1 485605.3552 1759873.414 80˚51’55.853” E 15˚55’04.922” N

2 485628.8823 1767731.453 80˚51’56.474” E 15˚59’20.667” N

3 493708.8476 1778070.718 80˚56’28.231” E 16˚04’57.284” N

4 500553.1154 1778070.718 81˚00’18.619” E 16˚04’57.313” N

5 506359.6028 1773516.306 81˚03’34.029” E 16˚02’29.059” N

6 506328.8541 1769763.893 81˚03’32.958” E 16˚00’26.935” N

7 508194.3786 1768072.466 81˚04’35.710” E 15˚59’31.867” N

8 502191.9333 1759826.360 81˚01’13.723” E 15˚55’03.538” N



5.2 Proposed Project

Based on the Geological, Geophysical studies and results of production testing during

the exploration and appraisal phases, the Block has been assessed to have distinct

commercial prospects from two hydrocarbon pays viz. Gollapalli and Raghavapuram

sandstones. Accordingly, the block is planned to be developed in a phase wise manner

through drilling of 31 wells. Out of these 31 wells, 30 are horizontal and 1 is vertical

wells. As the pays are tight in nature, hydraulic fracturing within these sands will play a

pivotal role in bringing the wells on production. 3-4 shallow wells for effluent disposal are

also planned.

The wells are to be brought under production consequent to creation and connection to

an Early Production System (EPS).

Successful commercial exploitation of these two hydrocarbon pays will augment the

production of oil and gas under the present scenario of ever growing demand of oil and

gas in the country.

5.3 Project Investment

The cost of drilling including rig hiring, daily drilling rates, consumables, well

accessories, hydraulic fracturing, land acquisition with respect to drilling of 31 wells is

envisaged to be Rs. 6792.00 crores. Out of these 31 wells, cost of 30 horizontal wells is

envisaged to be Rs. 6642.00 and cost of 1 vertical well is envisaged to be 150.00

crores. The cost for the establishment of the EPS is envisaged to be Rs.12.00 crores.

Therefore, the total project cost comes to Rs. 6804.00 crores

5.4 Project Justification

The Long term production profile envisages bringing 6 wells online annually and

ramping up production to a peak of 13,200 STB/ Oil and 54.8 MMSCF/d Gas till year

2020-21 and thereafter declining gradually to 3550 bbl/d Oil and 6.3 MMscf/d Gas by

March, 2035. It is estimated that cumulative 39.1 MMbbl Oil and 70.1 Bcf Gas will be

recoverable.

Techno-economic analysis of the proposed combined development strategy of the

Raghavapuram and Gollapalli pays in Nagayalanka field, having a Project NPV of

approximately 5262.00 Crores and IRR of 38%, indicates a healthy project and

potentially justifiable for commerciality to deliver positive investment returns exceeding

the cumulative contract costs given technically justifiable assumptions regarding

reservoir performance, development cost, operating cost and oil price projection.

6.0 Development Strategy

The Nagayalanka discovery is a deep, tight reservoir (depth >4000 m) having ambient

reservoir conditions of 150-170˚ Celsius temperature and 8000-9000 psi formation

pressure and classifies as a High-Pressure High-Temperature (HPHT) development.

Exploiting such reservoirs are technically challenging - the best possible approach is to

develop the field in a series of phases guided by acquired data from previous phases.

The drilling of inclined wells or horizontal wells from few clusters targeting multiple

pays, after examining their techno-commercial feasibility, are also envisaged to further



improve the economics and mitigate LAQ issues.

Hydraulic fracturing is essential to commercially flow these discoveries as both the

reservoirs have very poor permeability. Considering both the pays are very close to

each other vertically, commingled flow of the hydrocarbons is also envisaged. A

common surface facility - Early Production System (EPS) will be established to cater to

the extraction and delivery of the hydrocarbons.

7.0 Transportation of Oil and Gas for Marketing

The produced Oil along with the associated Natural Gas are both marketable

commodities.

Purified condensate/oil will be transported by road tankers to unloading station of ONGC

at S- Yanam for further transportation to M/s HPCL, Visakhapatnam.

Gas will be compressed and its evacuation will be done by the marketing tie up.

8.0 Technological Aspects

Technological aspects include operations related to drilling, cementing, logging,

stimulation and testing.

8.1 General Aspects of Drilling

Drilling operations will be carried out using an electrical type / VFD (Variable Frequency

Drive) drilling rig. The rigs are self-contained for all routine jobs. Drilling is likely to

continue for about 3-4 months for each well in the Block. Drilling unit for drilling of oil and

gas wells consists of a derrick at the top of which is mounted a crown block and a

hoisting block with a hook. From the swivel is suspended a kelly stem which passes

through a square or hexagonal kelly bush. This kelly bush fits into the rotary table. The

rotary table receives the power to drive it from an electric motor. The electric motor

rotates the rotary table which passes through the kelly bush and the rotations are

transmitted to the bit as the drilling progresses, the drill pipe in singles are added to

continue the drilling process. At the end of the bit life, the drill pipes are pulled out in

stands and stacked on the derrick platform. A stand normally has 3 single drill pipes.

After changing the bit, the drill string is run back into the hole and further drilling is

continued. This process continues till the target depth is reached.

During the course of drilling, cuttings are generated due to crushing action of the bit.

These cuttings are removed by flushing the well with duplex/triplex mud pumps. The

mud from the pump discharge through the rotary hose connected to stationary part of

the swivel, the drill string and bit nozzles. The mud coming out of the bit nozzles pushes

the cuttings up the hole and transports it to the surface through the annular space

between the drill string and the hole. The mud not only carries away crushed rock from

the bottom of the hole but it also cools the bit as it gets heated due to friction with

formation while rotating. The mud also helps in balancing subsurface formation

pressures and by forming a cake on the walls of the well diminishes the possibility of

crumbling or caving of the well bore.

At the surface, the mud coming out from well along with cuttings falls in a trough, passes

through the solids control equipment i.e. shale shaker, de-sander and de-silter. These



equipments remove the solids of different sizes which get mixed with the mud during the

course of drilling. The cleaned mud flows back to the suction tanks to be again pumped

into the well. Thus, drilling mud/fluid circulation is a continuous cyclic process. The most

suitable clay for mud preparation is bentonite which is capable of forming highly

dispersed colloidal solutions. Various other chemicals are also used as per

requirements dictated by the subsurface temperature/pressure condition in wells. The

mud is continuously tested for its density, viscosity, yield point, water loss, pH etc. to

ensure that drilling operations can be sustained without any down hole complications.

Once drilling operations are completed for each stage, casings are lowered and

cemented. Well is tested after making holes (perforations) in the production casing.

Production testing normally takes few days for each identified object. Finally, the well is

connected to a production installation (EPS) and put on regular production.

8.2 Drilling Operations

Salient features of the proposed drilling activity are given below under Table 4.

Table 4 Information on Drilling Activity

Well location / Depth Description

No. of wells to be drilled 31

Duration of Drilling 3-4 months for each well

Qty. of drilling fluid cu. m. About 700-800 m3 for each well

Qty. of drill cuttings, cu. m. 300-350 m3 for each well

Qty. of drlg. Waste water, cu. m. 1000 m3 for each well

Location Details Locations to be finalized

Distance of Block boundary from the coast

line

Onland Locations

Formation pressure 8000 - 9000 psi

Formation Temperature 150˚ - 170˚ Celsius

Test flaring duration 1 to 3 days for each object

Flare Details: Confined to the oil pit.

Flare stack of sufficient height

located at a safe distance from the

well mouth

Hired electrical type rigs with capacity to drill to ~5000 m are proposed to be deployed. It

is envisaged that two such rigs will be under simultaneous deployment.

Type of rig and associated requirement are mentioned under Table 5.

Table 5 Drilling Rig Type and associated infrastructure requirement

Description Details

Type of rig 2000 HP/ Electrical Rig (Type-III)

preferably VFD Rig with top drive

Drilling mud composition Water based Drilling Fluid till ~450 m

(26” hole); SOBM for the remaining

section till TD (~4700 m).



Power generator type & nos. AC – SCR Type (6 Nos)

Diesel consumption @ 3 - 4 kl / day per day per well

Quantity of fresh water requirement and

source

1000 m3. To be transported from nearby

source through contractual services

Manpower on rig As per Contractor’s Policy

Material requirement & Mobilization To be provided by the Contractor

Solids handling system on rig Shale Shakers – 1200 GPM Capacity

De-sander – 1200 GPM Capacity

De-silter – 1200 GPM Capacity

Sewage treatment facility, if any Not applicable

Quantity of waste water produced 15-20 m3/d

Waste Pit availability & Size 30’ x 33’ x 5’ - 2 Nos

38’ x 33’ x 5’ – 1 No.

23’ x 20’ x 5’ – 1 No.

Oil Pit availability & Size 3’ x 3’ x 4’ – 1 No.

The quantity of drill cuttings generated will be around 300-350 m3 from each

development well. The quantity of wastewater produced will be about 15-20 m3/day. The

rig will be provided with solids handling system comprising shale shakers, de-sander

and de-silter for cutting and fines handling and a degasser with vacuum pump for

making the drilling fluid free from gas bubbles, if any. The Mobile ETP will be installed to

process the drill site effluent, so as to deliver treated wastewater having the desired

characteristics of treated effluent as per the standards laid down by the APPCB

The well configuration will be telescopic, diameter decreasing with depth. The following

general well architecture is envisaged.

Depth Well Diameter Casing Size

Surface - 30 m 30” 30”

30 - 450 m 26” 20”

450 - 1750 m 17½” 133/8”

1750 - 2900 m 12¼” 95/8”

2900 - 4150 m 8½” 7” Liner

4150 - 4700 m 6” 4½”

The actual depths and casing policy may vary according to actual subsurface geological

position and formation pressures.

The casings will be cemented with oil well cement slurry of sufficient compressive

strength pumped within annular space between the open hole and the casing.

8.3 General Requirements of Drilling

Development drilling programme requires the following common facilities:

a. Drilling muds

Drilling of wells requires specially formulated muds which basically comprise of inert

earth materials like bentonite, barite in water with several additives to give mud weight,

fluidity and filter cake characteristics while drilling an oil / gas well. The drilling muds

have several functions like lubrication and cooling of the drill bit, balancing subsurface



formation, bringing out the drill cuttings from the well bore, thixotropic property to hold

cuttings during non-operations, formation of thin cake to prevent liquid loss along well

bore etc. Several additives are mixed into the mud system to give the required

properties.

Water based muds (WBM) are generally used for drilling. Specially designed synthetic

oil based muds (SOBM) are used under certain special conditions, particularly during

drilling difficult formations when encountered. Synthetic based mud systems are proven

to be highly efficient and eco-friendly in tackling difficult hole problems due to their high

fluid stability, greater shale inhibition and lower torque/drag values. Such synthetic muds

are being used worldwide in drilling operations.

The constituents of water based mud (WBM) are given in Table 6. The special additives

and their functions in WBM are shown in Table 7.

Table 6 Ingredients of Water Based Drilling Fluid

Sl. No. Chemicals

1. Barite

2. Bentonite

3. Carboxy Methyl Cellulose

4. Mud Thinner / Conditioner

5. Resinated Lignite

6. Non-Weighted Spotting Fluid

7. Weighted Spotting Fluid

8. EP Lube

9. Drilling Detergent

10. Caustic Soda

11. Potassium Chloride

12. Soda Ash

Table 7 Special Additives and their Functions in Water-based Drilling Fluids

Sl. No. Chemicals Function

1. Sodium bicarbonate Eliminate excess calcium ions due to cement

contamination

2. Sodium chloride Minimize borehole washout in salt zone

3. Groundnut shells, mica

of cellophane

Minimise loss of drilling mud to formation

4. Cellulose polymers or

starch

Counter thick, sticky filter cake, decrease filter

loss to formation

5. Aluminium stearate Minimize foaming

6. Vegetable oil lubricant Reduce torque and drag on drill string

7. Pill of oil-based mud

spotting fluid

Counter differential pressure, sticking of

drilling string.

Pill is placed down hole opposite contact zone

to free pipe

SOBM is low toxic synthetic oil, paraffinic in nature. The oil is converted into a strong

emulsion by addition of additives to withstand the rigours during circulations/drilling.



Synthetic based muds are biodegradable with very low toxicity and are specially

developed to be environment friendly. Proper handling of SOBM is essential to avoid

wastage or discarding of the mud. The drill cuttings are collected after shale shaker and

dried before disposal in an isolated pit with impervious lining and are buried thereafter.

Fine screen is used for SOBM mud and the screen should be oil wet. In general, SOBM

system is used after drilling of top hole. In the present project, drilling with water based

mud (WBM) may be carried out till the surface casing (26” hole) and SOBM used

thereafter.

For drilling the wells, SOBM having aromaticity of <1% will be used. SOBM services will

be implemented through contractual hiring of authorised / certified service provider. The

drilling cuttings will be collected, washed, treated thoroughly and discarded as per

guidelines on disposal of such solid waste. Unused SOBM will be collected and treated

for reuse / recycle by the service provided as per prevalent norms.

The constituents of a Synthetic Oil Based Mud (SOBM) are given in Table 8.

Table 8 Ingredients of Synthetic Oil Based Mud (SOBM)

Sl. No. Chemicals

1. Biocide

2. Oxygen Scavenger

3. Cellulose Fibre

4. Corrosion Inhibitor

5. Solvent Cleaner

6. Spotting Fluid

7. Surfactant- Cleaner

8. Zinc Carbonate

9. Synthetic Graphite

10. Oil wetting Agent

11. Rheology Modifier

12. Thinner

13. Calcium Carbonate (Coarse/Medium/Fine)

14. Emulsifier

15. Viscosifier

16. Fluid Loss Reducer

Remarks: Sl. No. 14-16 are High Pressure and High Temperature additives

b. Power Generation

The drilling process requires movement of drill bit through the draw works which require

power. The power requirement of the drilling rig will be met by using the AC – SCR Type

(6 Nos) Diesel Generator sets with a diesel consumption of about 3-4 kl/day. The

exhaust stacks of the DG sets are likely to vent the emissions.



c. Water requirements

The water requirement in a drilling rig is mainly meant for preparation of drilling mud

apart from washings and domestic use. While the former consumes the majority of

water requirement, the water requirement for domestic and wash use is very less. The

daily water consumption will be around 25 m3/d of which 15 m3/d will be used for drilling

purposes including mud preparation and 10 m3/d will be used for domestic purposes

including drinking.

During drilling with SOBM, requirement of water will be less.

d. Domestic wastewater

The operating personnel in the drilling rigs will operate from drill site accommodation

(DSA) in the vicinity of the location. Suitable soak pits will be available at the DSA.

e. Solids removal

The rock cuttings and fragments of shale, sand and silt associated with the return drilling

fluid during well drilling will be separated using shale shakers and other solids removal

equipment like de-sander and de-silter. The recovered mud will be reused while the

rejected solids will be collected and discharged into the waste pit.

When SOBM is used, the cuttings will be collected, dried and buried. Use of de-sander

and de-silter will be avoided during SOBM use.

f. Drill cuttings and waste residual muds

During drilling operations, approx. 300-350 m3 per well of wet drill cuttings are expected

to be generated from each well depending on the type of formation and depth of drilling.

In addition to the cuttings 15-20 m3/day of wastewater is likely to be generated during

well drilling. The waste residual muds and drill cuttings which contain clay, sand etc. will

be disposed into the waste pit. When SOBM is used, disposal of the cuttings needs to

be buried in an isolated pit after drying.

g. Chemical storage

The drilling rig will have normal storage facilities for fuel oil, required chemicals and the

necessary tubulars and equipment. The storage places will be clearly marked with safe

operating facilities and practices.

h. Manpower

The drilling rig will be operated by approx. 25-30 persons on the rig at any point of time.

For charter-hire rigs, the manpower may vary as per the Contractor’s policy. The

manpower will operate in two shifts with continuous operations on the rig.

i. Logistics

Crew transfers to and from the drilling rig, materials, diesel and chemicals will be

through light vehicles, trucks and trailers.

8.4 Brief on well logging

Open hole logging is carried out during various phases of drilling. Open hole logging

normally includes recording of resistivity, gamma ray, density, neutron, sonic logs and



other special logs as necessary. Cased hole logging includes recording of gamma,

neutron, and cement bond evaluation logs. Perforation of object is done with gamma

correlation. During production phase, periodic production logging is necessary.

8.5 Perforation

After casing and cementation, the well bore to formation communication against the

identified target objects (pays zones) is made by perforating the casing with help of

controlled explosives.

8.6 Stimulation

During stimulation, around 2400 to 3200 bbl gel with proppant sand is planned to be

pumped within each object in the well. For preparation of gel, water from nearby

sources will be transported by hired water tankers.

8.7 Well activation and Testing

Required testing facilities will be available at drilling rig for separation of liquid phase

and burning of all hydrocarbons during testing. The test flare boom will be located at a

distance from the drilling rig.

9.0 Production Facility

An Early Production System (EPS) for handling the produced oil and gas is planned to

be constructed at a suitable location depending on availability of land and

approachability from all well sites. The location of the Nagaylanka EPS will be the wells

site Nagayalanka #1Z-ST. It is expected that 15-17 wells will be connected to the EPS.

This EPS, with a handling capacity of 800 m3/d of Oil and 5,00,000 SCMD of Gas, will

have well pads with gathering manifold and well fluid transfer line, HP and LP

separators and Heater-treater followed by gas dehydration (dehydration unit) for gas

processing, storage tank for oil storage prior to transfer to an oil terminal, oil pumps,

gas compressors etc. Intra-field pipeline network will be connecting the wells to the

EPS. Purified condensate/oil will be transported by road tankers to unloading station of

ONGC at S- Yanam for further transportation to M/s HPCL, Visakhapatnam. The

stabilised oil can be shipped using Single Buoy Mooring (SBM). Gas will be

compressed and its evacuation will be done by the marketing tie up. The associated

produced water will be treated in ETP and further disposal of treated effluent will be

carried out by sub-surface injection in a well below a depth of 1000 meters from the

ground level. The treated effluent requires complying with the parameters with respect

to suspended solids and, oil/grease; limits being 100 mg/l and 10 mg/l respectively and

also with other permissible limits as per MoEF standards for Oil Drilling and Gas

Extraction Industry specified under Schedule –I in The Environment (Protection Rules),

1986

10.0 Ambient Air Quality Monitoring

Ambient Air Quality Monitoring to be carried in and around the drill sites and EPS

regularly.

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