This document provides the minimum standards and general practices for selection and management of drilling fluids.
A. GENERALITIES
1. A Fluids Programme shall be produced for each well and a summary included in the Well Programme.
2. Consideration shall be given to the toxicological and environmental properties of all drilling, completion and cementing fluid additives at the fluid programme planning stage.
3. The use of hexavalent (Cr VI) chrome mud additives, asbestos products and attapulgite clays is prohibited.
4. The use of all chemical additives shall be strictly controlled. In any case choice will be given to “environmentally friendly” chemicals.
5. Material Safety Data Sheets (MSDS) which provide detailed information on hazards, safe handling procedures and toxicological properties shall be provided at the rig-site and be readily available.
6. Chemicals shall be stored and handled in a manner that minimises the likelihood of contact with personnel and release to the environment.
7. Personnel protective equipment (PPE) shall be used at all times when handling chemicals.
8. Personnel required to handle or use hazardous chemicals shall be instructed regarding their safe handling, use and disposal.
9. Personnel shall be made aware of the potential hazards and the required protective equipment.
10. Hazardous chemicals shall be segregated as appropriate, stored in proper containers, and properly labelled in languages understood by all on the rig-site.
11. During well operations, testing and reporting of the properties of the active drilling fluid system shall be carried out to API standards.
12. For each well a minimum on-site stock level of weighting material and additives shall be specified in the well programme which shall take into account reasonable stock levels in case of losses. Unless a dispensation is obtained from the Well Operations Manager, drilling shall cease if the stock falls below this level.
13. Means for transporting chemicls must be checked in purpose to avoid contamination by previously transported chemicals
14. Local meteorogical conditions have to be taken into consideration for storing chemicals: E.G. resistance to cold or heat.
15. Once a chemical container has been open the remaining unsused chemical life span can be affected, this has to be taken in consideration for the stock management.
B. MINIMUM STOCK
1. Minimum stock of weighting agent and associated chemicals to be held at the site to increase the active volume mud weight of 0.25 sg.
2. The minimum surface volume of whole mud.
3. The requirement for, amount of and density of kill mud to be held for each section.
4. Sufficient volume of cement (and associated additives) to be able to pump two 100m length cement plugs in the open hole.
5. Wells shall be categorised according to the average borehole volume as below:
a. Light programme - less than 100 cubic meters
b. Medium programme - 100 to 250 cubic meters
c. Heavy programme - more than 250 cubic meters.
6. For exploration wells (with or without offset data) the minimum stock of weighting agent shall not be less than:
a. Light programme - 25 T
b. Medium programme - 100 T
c. Heavy programme - 150 T.
7. The inclusion of stocks stored on barges at the rig site may be taken into account dependant on the weather conditions at that location.
8. inimum surface volume of mud shall be maintained on the rigs shall be a minimum of
a. Light programme - 50 cubic meters
b. Medium programme - 100 cubic meters
c. Heavy programme - 150 cubic meters.
9. Dispensation may be sought when preparing the Well Programme from the above if there exists; ready availability of supplies, benign weather conditions guaranteeing delivery of supplies or other factors that mitigate risks.
C. OIL BASED MUD
1. Only select Oil Based Muds (OBM) if the use of alternative mud systems is not practicable. Selection will only occur following a detailed technical assessment and will be a Low Toxic OBM.
2. Will be taken into consideration:
a. Environmental risk and associated impacts.
b. If OBM is used, measurements of flash point will be taken on a regular basis to ensure it stays below the mud circulating temperature. Thorough assessment shall be conducted on additional fire fighting equipment if the rig mud pits are not equipped with a foam system.
c. Procedures which will be developed and implemented prior to, during and after drilling in order to avoid or minimise environmental impact associated with transport, handling, use and disposal of mud and cuttings and accidental spill.