1.0 Purpose

The purpose of this procedure is to ensure that the Annular Pressure (AP) Well Management is documented and that roles, responsibilities and safe working practices are clearly defined to ensure safety of the workforce, safety of the general public, and protection of the environment and company assets.    

2.0 Scope

The scope of this procedure relates to all wells with AP located within the Field.

Specifically this procedure relates to the following:

• Preparation of programmes and progress reports for managing wells with AP
• Instructions for monitoring wells with AP
• Instructions for pressure release from AP wells
• Instructions for maintenance and workover of AP wells
• Standard well abandonment programme
• Instructions for monitoring AP wells during gas injection

For the purpose of this procedure all AP wells are further categorised as follows:

• Category 1 - AP well with a sustained casing pressure of 100% Maximum Allowable Annulus Surface Pressure (MAASP) or greater

• Category 2 - AP well with a sustained casing pressure of between 50 and less than 100% MAASP

• Category 3 - AP well with a sustained casing pressure of between 25 and less than 50% MAASP

• Category 4 - AP well with a sustained casing pressure greater than 10 bars and less than 25% MAASP

A general overview of AP Well Management, testing, internal and external support is shown as a “flow diagram” in Appendix A.

3.0 Abbreviations and Definitions

BA:                 Breathing apparatus                                            

 DATA TRAP: An electronic monitoring device that can record four pressures and one temperature fluctuations simultaneously

ECG:                 Ecology Control Group. COMPANYbv Department who are responsible for advising all other departments within COMPANY on Health, Safety and Environmental issues

HSE:                 Health, Safety and Environment. A COMPANYbv Department who are responsible for advising all other departments within COMPANYbv on Health, Safety and Environmental issues

AP:                    Intercasing pressure. Any pressure within the 7/9 intercasing B annulus and 9/12 intercasing C annulus

AP MP:             Intercasing Pressure Management Programme that has been approved by AUTHORITIES

MAASP:            Maximum Allowable Annulus Surface Pressure. This calculated pressure is a function of the collapse pressure of the interior tubing or casing, the burst pressure of the exterior casing, the fracture pressure of the formation at the casing shoe; and the competence of the cement sheath on the exterior casing in taking into consideration the casing tolerance to hydrogen sulphide. A safety factor of 2.0 is applied to the MAASP calculation for each intercasing annulus of all wells

PPE:                Personal protective equipment. Specialised clothing and devices such as hard hats, flame retardant coveralls, boots, gas detectors and breathable air escape sets provided by the employer to an employee for personal protection of hazards within the work place

PTW:                 Permit to Work. A document issued by COMPANYbv for any work that ensures that the appropriate management controls are in place, that any hazards are identified, and appropriate hazard controls and safe working practices are adopted at the work location

RPE:                 Reservoir and Petroleum Engineering., A department of COMPANYbv

AUTHORITIES:          GGTN, Gosgortechnadzor                 

4.0 Responsibilities

4.1       The Subsurface Manager is responsible for ensuring that adequate funding and resources are made available for the safe operation of AP wells.

4.2       The Well Services Manager is responsible for ensuring that all AP wells are identified; and that the AP Management Programme, including appropriate procedures, instructions and controls, is in place and effectively implemented to ensure the safe operation of AP wells.

4.3       The Well Services Superintendent is responsible for ensuring that his personnel and contractors are made aware of the procedures, instructions and controls relating to AP wells.

4.4       Well Services Personnel (COMPANY or 3^rd Party) are responsible for ensuring they understand and adhere to all procedures, instructions and controls relating to the safe operation of AP wells.

5.0 Procedures

5.1    Implementation of AP Management Programme and Preparation of Progress Reports

 COMPANYbv implements the AP Management Programme (Appendix F) that has been approved by AUTHORITIES to ensure the safety of AP wells in the field.

Reports on the status of AP wells are issued quarterly and annually. These reports detail the status of the AP wells and review actions taken and planned. Such reports are distributed to AUTHORITIES (Uralsk) and West Kazakhstan Oblast Department on Emergency Situations (WKODES).

5.2 Instructions for monitoring AP wells

5.2.1   Regular monitoring and analysis of pressure is essential to the management and integrity of all wells. To verify that safety and well integrity standards are met, accurate records of monitoring must be kept. These records must be madeavailable for both internal and external audit and review.

5.2.2   Monitoring, recording and data analysis shall be undertaken as follows:           

• Monitoring pressure on tubing, tubing/casing (A annulus), 7/9 intercasing and 9/12 intercasing (B and C annuli)
• Weekly monitoring of production wells that are producing
• Weekly monitoring of wells with AP that are not operating
• Monthly monitoring of all other operable wells in contact with the reservoir

5.2.3   The aforementioned schedule shall be adhered to except when conditions prevent monitoring. Any exceptions to the monitoring schedule shall be noted in the appropriate reports.

5.2.4   A data base will be maintained including all wells and their associated monitoring data for analysis and query.

5.2.6   In addition to the aforementioned instructions, refer to Appendices A and B – AP Management and Monitoring Flow Chart.

Note: It should be recognised that well pressure may change as conditions of temperature, well flow rate and reservoir pressure change. This is a naturally occurring phenomenon.

5.3 Instructions for pressure release from AP wells

5.3.1 It should be recognised that annuli may be bled on a regular basis to maintain pressures below the MAASP. Controlled bleeding can also provide valuable information about the well. The most critical information a “controlled bleed down” can provide is the capacity to sustain fluid flow to the surface.

            (Refer Appendix E for Guidelines for Controlled Bleeding and Sampling Safety)

            On selected wells, control bleed down will record the following:

• Time required
• Type of fluid/ fluids returned
• Pressure build up/ draw down rate

5.3.2   In order to combust sour hydrocarbons that contain sulphides and H₂S, bleeding operations shall be performed simultaneously with burning of the bled hydrocarbons, transforming sour components into less toxic compounds.

5.3.3   All information gathered shall be entered into a data base for future analysis and query.

5.3.4   Details of intercasing pressure evaluation of AP bleed/ build up pressure data is as follows:

• Plot pressure versus time for each bleed off period. Note any pressure responses from adjacent annuli during bleeds – pressure response may indicate communication between annuli
• Note the rate at which any pressure response behaves during bleeds. Evaluating the rate art which a pressure response is observed will aid in determining the source of communication
• Note the time necessary to obtain a full bleed off to zero. This time will aid in determining the severity or depth of communication
• Ensure pressure responses are not due to a change in tubing pressure. Correlating to tubing pressure will ensure that pressure responses are not associated tom a change in well dynamics
• Plot each pressure versus time for build up period. Note the rate and pressure that each annuli is building. This will aid in determining string communication
• Note the time necessary to build back up to “pre bleed” levels. This will in determining the severity and depth of string communication
• Note any “bypassed” strings where pressure is absent or anomalies can be seen. This will aid in indicating possible gas migration behind pipe
• Sampling and the analysis of the composition of bleed gas/ liquid will aid in determining if source is from communication or from gas migration behind pipe

            (Refer Appendix E for Guidelines for Controlled Bleeding and Sampling Safety)

Following a review of the above data, a conclusion will be drawn on the intercasing pressure source and severity. From this conclusion, appropriate action may or may not be taken depending on the cause of pressure and the capacity to remove it.  

Note: Bleed down of the intercasing pressure should be considered as only as a temporary means of AP control. The appropriate responsible department within COMPANYbv will evaluate and carry out a controlled bleed down programme on a well by well basis.

5.4    Instructions for maintenance and workover of AP wells

5.4.1   Killing. When appropriate, wells with AP may be killed to reduce the magnitude of pressure. Killing shall be based on well category and other considerations related to workover activities and field development.

5.4.2 Rigless intervention. Rigless activities are effective to remedy AP in specific well conditions. For example, the installation of through tubing bridge plugs (TTBP) within the tubing to isolate the producing reservoir in non producing wells.

5.4.3  Workover. Workovers are conducted either to restore or improve production capacity, or to change operating status (eg. from producer to gas injector), or to improve the safety of the well by either suspending, abandoning, improving the AP status or other considerations related to field development.

The workover schedule will be planned on a long term basis to allow for procurement of equipment required for workover of a specific well, and to allow for site construction and rig logistics as appropriate.

5.4.4   After workover, wells will be monitored daily to assess the effectiveness of the rig operation. During workover operations, mechanical completion data will be evaluated (eg. tubing inspection after retrieval). 

5.4.5   A data base will be maintained to include “mechanical completion data”.

5.5    AP Well Abandonment Programme

5.5.1   AP wells may have mechanical problems that require suspension or abandonment. Decisions on AP well suspension and abandonment require the consideration of safety and commercial aspects.

5.5.2   When the decision to suspend or abandon an AP well has been decided, a suspension/ abandonment programme will be produced by COMPANYbv and then approved by AUTHORITIES.

5.5.3 The suspension/ abandonment programme shall include:

• The elimination of AP and cross flows that are related to poor quality casing and cementing within the intervals containing toxic and aggressive media, prior to the commencement of abandonment operations

• A special programme to take account of any complications or emergency situations during well abandonment

• Isolation and abandonment operations to eliminate the possibility of toxic and aggressive media appearing at the wellhead, and to protect the casing string from corrosion after well abandonment

• When abandoning wells containing toxic and aggressive media, all exposed horizons will have to be isolated from each other by setting cement bridge plugs with the height equal to that of the horizon plus 50 metres; and for the top of the upper horizon plus 100 metres. Brine treated with corrosion inhibitor will be pumped into all formations in sufficient quantity prior to a cement plug installation

• If it is not possible to isolate all exposed horizons and if they are not interconnected by cross flows, a lower cement plug of greater than 100 metres is to be set at the maximum possible depth

• A cement bridge plug will be set across the intermediate casing shoe depth that is no less than 50 metres above and below the shoe

• The wellbore above and below the cement plug will be displaced with brine treated with corrosion inhibitor  

• When abandoning wells with production casing ran in sections, cement plugs will be set 50 metres above and below the crossovers  

• When abandoning wells with partially cemented liners or non cemented shoes of the previous casing, cement bridge plugs of 50 metres above and below the liner hanger

• A well with collapsed casing caused by salt movement (over 20% of the inner diameter, 10-15% of 5” casing) may be abandoned if it is not feasible to straighten the casing string without damaging it; and if all attempts to retrieve tubing from below the collapsed section have failed. A cement plug of no less than 50 metres high will be set to isolate the damaged zone below and above to the maximum extent depending on the collapsed interval

• To ensure reliability of isolation/ abandonment operations to be carried out, a LCM pill will be pumped in through the tubing. It is acceptable not to perform this operation if it is not possible to remove any sludge from the tubing or tubing shoe

• Cement used for plug installation will be resistant to the toxic and aggressive medium

• The strength of the cement bridging plugs will be tested by weight loading with the drill string and by pressure testing the production casing. The load is set with regard to the maximum allowable load for cement stone (160 kg/ cm² or 157 bars) but shall not exceed 15 tons force

• The quality of the bridging plug set in the last intermediate casing is confirmed by hydrostatic test and fluid level decrease depending on the casing strength

• To avoid the effect of defrosting at surface the upper 50 metres will be displaced antifreeze. Any back pressure to offset the formation has to be no less than that specified by AUTHORITIES regulations

• The wellheads of wells being abandoned will consist of a casing head, tubing head, corrosion proof high pressure valve and a flange. The hand wheels and the gauges will be removed with all flanges sealed with blind flanges

• A 2 x 2 x 0.5 meter concrete pad will be constructed around the wellhead surrounded by 1 metre high metal fencing. A sign post of 0.5 metres height should be installed on the pad close to the wellhead. This sign post should be made of pipe of 60-70 mm (2-3/8 or 2-7/8” OD) with a metal plate welded to it.

           The following information should be indicated on the plate:

           Well number

           Field name

           The company that drilled the well OR operated the well

           Start up and accomplishment dates of drilling or operation and warning:

           “ОСТОРОЖНО ­– СЕРОВОДОРОД” (Danger! Hydrogen Sulphide!)

           All this information will be written by welding

• The wellhead status will be monitored one month after abandonment and every two years thereafter by COMPANYbv Production Department, with pressure surveys and air monitoring conducted in the vicinity of the wellhead

• If gas is detected at the wellhead of abandoned well, measures will be taken to determine the source. Additional abandonment operations will be undertaken

• Supervisors of abandonment operations will be engineers assigned by COMPANYbv Management. The supervisor will additionally instruct the abandonment team on safety and ensure provision of PPE and air monitoring devices

• Each individual well abandonment programme will include a section describing safety measures to be taken whilst conducting these operations

• While undertaking abandonment operations, a reliable communication shall be maintained with the head office of the company conducting the activities

5.5.4 Well abandonment recording procedure is specified in Section 2 of: “Procedures for Oil, Gas and Other Well Abandonment and Writing-Off of Well Construction Costs” issued by the Ministry for Oil and Gas Industry AND Ministry for Geology and Subsoil Protection of Kazakhstan, Order #63 “121-П” effective from 2^nd June 1995.

5.6 Instructions for Monitoring AP Wells during Gas Injection

• Gas injection into the producing formation shall be carried out on permission of the Central Commission for Development of Oil and Gas Fields of the Ministry of Energy and Mineral Resources of the Republic of Kazakhstan.

• During gas injection operations reference should be made to:

 “Industrial Safety Regulations for the Injection of Hydrocarbon Gases, including those containing Hydrogen Sulphide; into the Productive Formations of Oil, Gas and Condensate Fields in the Republic of Kazakhstan” that has been approved by AUTHORITIES and the Ministry of Energy and Mineral Resources, and registered with the Ministry of Justice of the Republic of Kazakhstan.

• AP wells management shall be managed in compliance with the “Intercasing Pressure Management Programme for the Oil, Gas and Condensate Field” Refer Appendix E.

• AP wells shall be managed in accordance with the regulatory documents in force.

• Gas injection wells with AP will be monitored continuously.

• Production wells in proximity to gas injection wells shall have their intercasing pressures monitored daily.

• If increases in intercasing pressures are noted in those producing wells in the proximity of gas injection wells, testing of those production and/ or gas injectors will be undertaken to determine if there is any pressure interaction between wells.

• In wells with AP, composition of annulus fluid shall be regularly sampled and analyzed to assist in determining the likely cause of intercasing pressure.

• Well operations shall be conducted to minimize changes in operating conditions and to reduce the frequency of shut in/ start up cycles.

• Wellhead assemblies shall be regularly tested for possible sources of intercasing pressure.

• Migration of injected gas into the formation shall be monitored, using the methods applied in the industry, to predict breakthrough of injected gas to producing wells.

6.0 Safety, Ecological and Environmental Controls within the Field

Due to the hazardous nature of produced gas (ie. high concentrations of H₂S) within the field, strict safety and environmental controls must be observed as follows:

• When working at a well site all personnel must wear appropriate PPE. As a minimum hard hat, flame retardant coverall and safety boots
• H₂S detectors must be available and operable
• Each member of the work party must have a BHA escape set
• At least one member of the work party must have means of communication in case of any emergency
• All work must be carried our under the appropriate COMPANYbv PTW
• Any flaring associated with AP work may only be carried out when the Field ECG staff have issued a flaring permit (in addition to the PTW referenced before). Flaring may only take place foe the duration specified on the flaring permit and associated PTW. If conditions change such as toxic fumes or smoke, impact on other work locations or surrounding villages then flaring must stop immediately
• Refer Appendix E: Guidelines for Controlled Bleeding and Sampling Safety

7.0 References

• COMPANYbv Permit to Work System

• COMPANYbv Flaring of Hydrocarbons from Flow Lines within the Field Procedure

• COMPANYbv Personal Protective Equipment Procedure

• Intercasing Pressure Management Programme Oil, Gas and Condensate Field Annual Report

• “Procedures for Oil, Gas and Other Well Abandonment and Writing-Off of Well Construction Costs” issued by the Ministry for Oil and Gas Industry AND Ministry for Geology and Subsoil Protection of Kazakhstan

• COMPANYbv Standard Well Abandonment Programme for Sour Wells

• Intercasing Pressure Management Programme Oil, Gas and Condensate Field

• Infield Pipelines Emergency Response Plan

• Drilling/ WEOP’s Emergency Response