SPE 149913

Integrated project for exploration wells drilling in Kirinskiy license block, offshore Sakhalin Island M.Tsemkalo, D.Sorokin, S.Zorina (Gazflot LLC), A.Zaprometov, O.Zhdaneev (Schlumberger)

Copyright 2011, Society of Petroleum Engineers This paper was prepared for presentation at the SPE Arctic and Extreme Environments Conference & Exhibition held in Moscow, Russia, 18–20 October 2011. This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of SPE copyright.

Abstract This paper discusses the HC exploration project implementation approach in the conditions of the Russian continental shelf, at the examples of wildcat and exploration wells Kirinskaya-2, Kirinskaya-3 and Yuzhno-Kirinskaya-1, in the Kirinskiy license block, offshore Sakhalin Island.

Operations were held in summer seasons of 2009 and 2010, and comprised planning, key risks analysis and mitigation, optimization of drilling, well logging and testing technology mix. Technical specifics of the projects were caused by insufficiently developed infrastructure, short operation period (from summer to early autumn), simultaneous operations from a number of semi-submersible drilling rigs (2010), and necessity of quick decision making in real time.

Technical input

• Systematic selection of well logging technologies and testing program, data integration for further wildcatting and exploration drilling tasks;

• Description of problems and complications while well drilling, logging and testing and remedial measures.

• A list of preparatory works for project implementation was compiled at the early planning stage. • Organization and personnel qualification requirements were described. Time-schedule breakdown was

provided for each type of operations. Issues of logistics and customs regulation related to mobilization of personnel, materials, and equipment were discussed.

The paper was divided into the following sections:

1. Project Planning: Schedule Compiling 2. Estimating Key Risks of Project Implementation 3. Project Participants Cooperation Arrangement 4. Logging-While-Drilling, Wireline logging and Well Testing technology mix Optimization 5. Logistics and Customs Support 6. Time Efficiency Analysis by the types of operations: Case Study 7. QHSE Challenges 8. Lessons Learned and Operation Efficiency Enhancement potential

Application The described approach could be used for exploration drilling and completion project implementation in the Russian offshore environment. The lessons learned will be used by the project participants at the next Russian offshore drilling projects. Results The Project was successfully implemented within the schedule. The selected technological complex enabled to find efficient solution to specified geological tasks.

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1. Project Planning: Schedule Compiling Project objective was HC reserves estimation in the Kirinskiy and Yuzhno-Kirinskiy license areas offshore Sakhalin; this involved exploratory well drilling, logging and testing using semi-submersible drilling rigs (MFDR - mobile floating drilling rig) during summer navigation period (June-October) 2009 - 2010.

Specifics of operation in the Russian offshore area are such that it is impossible to ensure successful investments without due planning and detailed preliminary study.

The project was implemented by Gazflot LLC in collaboration with leading suppliers and service contractors who have experience working in the offshore environment.

Time-restriction of work period is one of the main factors influencing the success of such projects. Well has to be drilled, logged and tested during the summer navigation period from early June to mid-October. Navigation is possible outside this time window, but in the autumn-winter period it is associated with increased technical and technological risks related to the weather conditions: the onset of severe storms and freezing ambient temperatures.

Thus, for objective reasons there is a need for careful consideration and planning of the entire well construction, logging and testing process along with the study of possible deviations from the original plan and drafting a contingency plan of action in emergency situations.

The large number of project participants (companies and organizations) and the need to coordinate their actions is another factor complicating the project implementation. Disputes and controversies between the parties inevitably arise; this could be related to the issues of internal organization of companies, different approaches to security requirements, differences in regulation documents, language barriers, etc. The purpose of work coordination is to ensure that all parties involved understand the tasks and challenges, have clear KPIs for their activity and for the project as a whole, and work in alignment as a result.

Table 1 below presents a breakdown of the stages and the time required for operations in wells Kirinskaya-3 and Yuzhno-Kirinskaya-1.

Table 1. Project time breakdown.

№ Project Stage Estimated time

spent,Days

1 Compiling individual operation plan for drilling and construction of an exploration well

60

2 Determining the type of rig, selection and contracting of drilling contractors

60

3 Defining the list of necessary studies and preparation of terms of reference for the tender for service work

30

4 Competitive bidding, selection of contractors for the required services 30

5 Well-construction, logging and testing operations simulation "on paper", drafting the preliminary programs

20

6 Contract negotiations with the contractors and signing the contracts 20

7 Mobilization of drilling rigs, personnel and equipment of contractors 20

8 Positioning of drilling rigs, solving the formalities required to obtain permits for commencement of work from the regulatory bodies

10

9 Well drilling and construction 80

10 Well logging and testing 20

11 Well suspension or abandonment 7

12 Demobilization of service contractors, drilling rigs 5

13 Laboratory studies, data processing, reserves estimation and presentation to the State Reserves Commission

60

Total 422

SPE 149913 3

The above table reveals necessity of an early planning and preparation phase for such projects - it is recommended to be started a half-a-year before the date of well spud.

As the Client Company did not have previous experience of operations in the Sakhalin offshore environment, drilling schedule for well Kirinskaya-2 was planned based on the experience of works undertaken in the other regions and using estimates from suppliers by the types of operation.

Figure 1. Layout of drilling exploration well Kirinskaya-2

Based on the project schedule, the service companies compiled their plans for mobilization of personnel, equipment and materials.

For wells Kirinskaya-2 and the Yuzhno-kirinskaya-1 drilled in 2010 the project implementation plans were based on the experience gained during drilling the well Kirinskaya-3.

2. Key Project Implementation Risks Assessment. Risk assessment and mitigation were performed on the basis of the approach of the major International Oil Companies.

At the early stages of planning we compiled a list of possible risks and accidents arising from the project implementation by the types of operations. Each risk was assessed by two parameters: the probability of occurrence and severity of the consequences; the weighted average risk factor was then obtained and a two type activity list was compiled:

• Preventing measures (the measures aimed at preventing accidents);

• Remedial measures (the measures aimed at minimizing the consequences of the accident).

Subsequently, we compiled a plan of implementation of the above activities. The implementation of this plan enabled to reduce the risk ratio to a level deemed appropriate by the project participants.

3. Project Parties Cooperation Arrangements. As mentioned before, the big number of participants was a specific feature of the project. Sufficient to mention that more than 10 contractors on the main services only participated in the project implementation; each, in turn, subcontracted a number of other suppliers and services.

"Rules and Regulation for relationship of the project participants" is the main document regulating the interaction between parties involved; this document regulates:

• Division of responsibilities between the project participants;

0

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1000

1250

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1750

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2250

2500

2750

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3250

3500

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Dep

th (

m)

Planned well construction cycle

OH WL LOGGING

plan

CSG 9 5/8" -

2350м

Drilling 30" - 160м

Mobilization+preparation

CSG

20" -

Pilot hole

CSG 13-3/8"

- 1200 м

WELL TESTING

P&A and Tail pipe 6-5/8" -

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• Decision making process;

• A list of persons in charge of decisions made with contact information (phone numbers, email

addresses, etc.);

• Timing of notification of mobilization and demobilization of personnel, equipment and materials;

• Shipping schedule for supply vessels, procedures for personnel gather and transportation from

mobilization points to drilling site and back;

• Access to rig communications facilities;

• Procedures and limitations of the data transmission

Each contractor shall appoint a coordinator, whose responsibilities include the following:

• Be the only authorized representative of the contractor;

• Coordinate and manage the contractor’ and subcontractors’ service units;

• Organize and control the timely mobilization of personnel, equipment and materials provided under the

contract in accordance with the drilling program;

• Ensure QC and compile the required report documentation;

• Monitor compliance with the HSE standards;

• Prepare weekly plans for maintenance works;

• Monitor the availability and consumption, maintain inventory of supplies provided under the Contract to

onshore base and rig;

• Coordinate the movement of the contractor’ equipment, materials and personnel between the rig and

onshore base to ensure a coordinated program implementation within the approved deadlines;

• Prepare and submit well drilling reports.

Gazflot LLC Sakhalin branch held conference calls with staff on the rig site on a daily basis since the beginning of rig transportation from Singapore till demobilization back from Sakhalin. During those meetings the management discussed daily reports, upcoming work, the need for the materials and expertise, staff accommodation rig, HSE events and other current issues. The importance of such communication cannot be overestimated: an active participation of the coordinators of all contractors was a major factor in the project success.

4. Logging-While-Drilling, Wireline Logging And Testing Technology Mix Optimization. Identification of hydrocarbon reservoir layers and determination of their saturation were the main objectives of the wireline logging campaign complemented with well test support and cement evaluation.

Extended LWD complex studies were performed in depth interval of 2225m-3100m; well logging tools were a part of the BHA, including gamma ray, litho-density, neutron log, acoustic, array laterolog (3-probes) tools, as well as caliper and inclinometers.

LWD enabled for lithological subdivision of the section, reservoir identification and estimating fluid content; however, LWD derived in preliminary conclusions that were refined after Wireline Logging operations in open hole.

Here we would like to point out a number of LWD process advantages:

• LWD data is obtained in real time as the drilling progresses;

• These log data are the "first picture" of sedimentary section, and are the basis for comparison with

wireline logging data; such a comparison allows an easier mud invasion zones identification, i.e., zones

of potential reservoirs

• Obtaining log data at the drilling stage provides more time allowances for good planning and compiling

MDT schemes (number of zones for testing, drilling-in sumps to drop-off perforators, etc.)

• In cases where the tool RIH is difficult or impossible due to borehole conditions or other reasons, the

LWD data could become the only source of information on sedimentary section.

The primary Wireline Logging services utilized are described below, and listed in the Table #2. Selection of the Wireline Logging services was determined by requirements of Reserves State Committee to validate the discovery of hydrocarbon asset and establish a production strategy.

The implemented open borehole wireline logging methods includes the following components:

• Evaluation of naturally occurring gamma rays in the formation adjacent to the wellbore (GR);

SPE 149913 5

• Porosity evaluation by means of measurement of hydrogen index of downhole formation (CNL*);

• Measurement of formation density and formation photoelectric factor by means of three detector

lithology density tool (TLD*);

• Spontaneous potential measurement (SP);

• True formation resistivity measurement (Rt) by means of high resolution laterlog array tool (HRLA*) with

five independent, actively focused depth- and resolution matched sections;

• Two-axels caliper measurement with powered positioning device and caliper (PPC*);

• Borehole Compensated Sonic logging measurement (Dt);

• Total gamma ray spectra measurement of naturally occurring radiation (NGS*) from three the most

common components (Th, U, K);

• Open hole formation conductivity measurement as a function of both depth and distance from the

borehole by means of array induction tool (AIT*);

• Micro-cylindrically focused log (MCFL) to measure of the invaded zone (Rxo), mudcake thickness (hmc),

and mudcake resistivity (Rmc);

• Modular formation dynamic tester (MDT*) for reservoir pressure measurement.

To further enhance the reservoir description the following services were additionally mobilized:

• Elemental capture spectroscopy sonde (ECS*) to measure relative elemental yields for Si, Ca, Fe, Al,

Su, Ti, Gd, S, Cl, H based on neutron induced capture gamma ray spectroscopy;

• Fullbore formation micro-imager tool (FMI*) to provide an electrical borehole image;

• Combinable magnetic resonance tool (CMR*) for nuclear magnetic resonance logging to determine total

formation porosity for storage quantification, estimate formation permeability and bound- and free-fluid

volume indicators;

• Tough logging condition conveyance system (TLC*).

Cased hole logging program incorporates the cement evaluation operation (CBL-VDL), depth correlation for perforation and production services (PSP*) to measure temperature and pressure, average fluid velocity, water and hydrocarbon holdups during well testing stage.

Table 2. Wireline logging suite for Kirinskaya-2 well

Section, Bit size Logging Measurement Logging interval, m

Top Bottom

Conductor, 508 mm GR-CH, DSLT-CBL, CCL 102 350

444.5 mm open hole SP, HRLA,GR-PEX, DSLC-BHC, CNL-PEX, TLD-PEX, PPC, HTEM

350 1200

339.7 mm casing GR-CH, DSLT-CBL, CCL, PTEM 102 1200

311.1 mm open hole GR-CH, DSLT-CBL, CCL, PTEM 1200 2350

244.5 mm casing GR-CH, DSLT-CBL, CCL, PTEM 1000 2350

215.9 mm open hole SP, HRLA, MCFL-PEX, GR-PEX, DSLC-BHC, CNL-PEX, TLD-PEX, AIT-PEX, HNGS, PPC, HTEM, MDT, CMR

2350 3100

168.3 mm casing GR-CH, DSLT-CBL, CСL, PTEM, PSP: PTEM, PMAN, PFCS

2100 3100

Before mobilization to the offshore platform all equipment went through a thorough maintenance cycle and required periodical calibration.

A zero offset vertical seismic profile operation was performed in the liner and intermediate cased hole section of the well in the interval 110-3060 m to acquire vertical velocities and proceed with correct interpretation of surface seismic data. The seismic survey was executed with 3-gun cluster of G-Guns that were deployed in the sea at a distance 45 meters from the wellhead of the azimuth of 215 degrees. Overall the waveforms were stable and

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repeatable.

During the well test stage in 2009 the wireline logging activity was related to the temperature surveys, perforation correlation that was simultaneously a gauging to confirm that it would be possible to initiate the perforation guns with drop bar and a liquid level measurement to validate required depression.

All involved in the logging operations personnel including the rig crew was participating in the safety toolbox talks before every logging descent. Special attention was brought to the lifting operation during rig-ups and rig-downs, activities with radioactive sources and logging cable under tension.

Hot permit system was in place on the rig and non-standard operations with high risk potential like logging with tough logging condition conveyance system, fishing operation, and activities with high pressure equipment were reviewed in details using hazardous analysis and risk control documents prepared to identify potential risks and prevention and mitigation factors.

The planned wireline set of logging measurements was executed successfully. The logging program was modified during the ongoing operation and additional services like ECS, CMR and TLC were mobilized in a short notice for the final open borehole section to enhance the reservoir appraisal. Hydrocarbon zones identification, adjustment of logging program (e.g. to identify the nuclear magnetic resonance measurement stations and reservoir pressure measurement points) and reservoir properties evaluation was done in real-time with involvement of petrophysicist and reservoir domain champions.

5. Logistics and Customs Support. Due to the fact that the rig after being set on the point of drilling in the Russia offshore zone beyond the 12-mile radius acquires the status of the customs territory of the Russian Federation and the Customs Union, the import of foreign goods can only be provided after customs clearance at the crossing point of the state border and placement under the customs regime, providing the opportunity to use goods in the customs territory of the Russian Federation.

Thus, the shipment of the equipment is provided from one customs territory to another with crossing the Russian border. Temporarily imported goods cannot be exported outside the customs territory of the Russian Federation without closing the regime of temporary import (Article 277 of the Customs Code of the Customs Union). In this case the goods get the status of foreign goods; however, the goods having the status of Russian origin are only eligible to be supplied to the rig located at the customs territory of the Russian Federation and Customs Union.

In the event the goods subject to transportation from the offshore rig to the ports of Russia have got, for customs purposes, the status of Russian goods (purchased in Russia or released into free circulation on the territory of the Russian Federation), such goods shall not be subject to customs clearance, and their customs control shall be carried out in a simplified manner on the basis of shipping documents.

Mobilization layout scheme could then be described as follows:

The entire delivery cycle as per the above scheme usually takes 5-6 days taking into account the two-day trip time. Cargo manifest is the main document confirming the completeness of the cargo.

6. Time Efficiency Analysis: Well #1 South-Kirinskaya - Case Study

SPE 149913 7

Figure 2. Time breakdown - all phases of well drilling, logging and testing

Well head

and BOP;

6,74%

Conductor

csg; 0,84%

Drilling;

29,57%

Casing;

4,94%Cementing;

8,79%

Coring;

5,27%

WL

Logging;

10,64%

DST

preparation

s and RIH

POOH ops;

2,40%

Well

testing;

24,65%

Postioning,

Rig up/Rig

down

works;

6,19%

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Figure 3. Time-Depth curves analysis: Planned vs. Actual

7. QHSE challenges The unique nature of the offshore Sakhalin Island has specific requirements for environmental and safety issues. Drilling was carried out with the provision of "Zero Discharge" into the sea - that is, all wastes generated during well construction and testing were removed and disposed of onshore with the use of modern technology. Using hi-tech torches in well testing provided the complete combustion of all the well fluids.

Safety of operations was provided by careful planning, risk analysis and minimization, strict control over the qualifications of personnel involved, and observation of rules and safety standards at works in the offshore environment.

The above measures, along with the use of modern technology made it possible to avoid accidents with personal injury and minimize the impact on the environment.

Floater positioning and preparations

Drilling 215.9 mm

pilot

Drilling 914,4

mm section

Drilling 660,4 mm

section

RIH and cementing

508 mm surface csg

RIH 762 mm

Conductor pipe

Drilling 444,5

mm hole

OH logging

RIH and cementing intermediate csg

339,7 mm

Drilling 311,1

mm hole

OH logging in 244,5 mm hole

RIH and cementing intermediate csg

244,5 mm

OH logging 215,9

mm hole RIH and cementing 168,3 mm

Drilling 215,9

mm hole Testing and plugging 3

objects P&A

Coring215,9 mm

Yuzho-Kirinskaya 1: Depth vs time planned and actual

Dep

th (

mete

rs f

rom

ro

tary

tab

le)

SPE 149913 9

For further improvements in this area, prior to implementation of the each subsequent projects it is important to come back to the lessons learned and act in accordance with the obtained earlier experience

8. Lessons learned and operation efficiency enhancement The main conclusion obtained in the course of the works in the seasons of 2009-2010 is the need to plan an equipment engagement scheme (including spare sets) at an early stage of preparatory work:

• Application of LWD technology in the wildcatting and exploration drilling with a view to operative adjustments of the drill bit programs, Wireline Logging programs to minimize the risks during the log on the cable (the risk of equipment failure, tool stack in the borehole);

• Possibility to use sets of downhole equipment (including spare sets) from the neighboring rig to reduce the percentage of failure of high precision and sophisticated equipment;

• Application of TLC equipment for logging the vertical wells at high probability of borehole breakout;

• Operative interpretation of MDT, XPT data for accurate estimation of reservoir pressure gradient, mud invasion zone, type of formation fluid for further well testing ;

• Compiling supply chain layout for mobilization of personnel and equipment for drilling rigs, taking into account the immediate vicinity of the work sites;

• Good planning and compliance with the above conditions will significantly reduce time and cost of well construction in general.