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Environmental Impact of the Offshore Oil and Gas Industry by Stanislav Patin - a unique summary of world-wide studies on the environmental issues associated with offshore oil and gas exploration and development

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Muddied Waters

A Survey of Offshore Oilfield Drilling Wastes and Disposal Techniques to Reduce the Ecological Impact of Sea Dumping

by Jonathan Wills, M.A., Ph.D., M.Inst.Pet., for Ekologicheskaya Vahkta Sakhalina (Sakhalin Environment Watch); 25th May 2000

Environmental Effects of Drilling Waste Discharges (continued)

"Non-Water Quality Environmental Impacts"

By February 1999 the oil industry appeared to have convinced the EPA that not only should the industry's commercial concerns be given due prominence in considering new legislation to regulate discharges, but also that the measures proposed should be placed in a wider environmental context. This allowed them to argue that dumping certain substances in the ocean would be less environmentally damaging, overall, than hauling it to shore for proper treatment, and to persuade EPA, in effect, to abandon zero-discharge as a pollution control mechanism.

This ingenious (critics might say ingenuous) intellectual contrivance is neatly summarised in Veil's paper:

In February 1999, the EPA proposed a regulation on SBMs that considered two options: a discharge option and a zero-discharge option. The EPA chose the discharge option for the proposal because it believes that the water quality impacts of appropriately controlled SBM discharges are less harmful to the environment than the non-water quality environmental impacts (fuel use, air emissions, etc.) that would occur if zero discharge had been selected. The EPA also believes the discharge option will encourage the further use and development of SBMs as a pollution-prevention technology. The proposed regulations present control measures the EPA thinks are adequate and appropriate.

Once again, the industry had volunteered for regulation and then talked the regulatory authorities into agreeing that was economically best for the industry was also environmentally best for everyone. Similar arguments are currently being advanced by the industry to OSPAR on the other side of the Atlantic, but here they have a problem - European research does not back the contention that SBMs are "a pollution-prevention technology" or that they "exhibit lower toxicity" than OBMs. Consequently the 12% of SBM that can remain on drill cuttings even after being processed by the primary and secondary shale-shakers on drilling installations (Veil, J. A., et al. 1999. op. cit.) is not acceptable under the proposed new European standards. Nonetheless, it appears that some OSPAR officials and European politicians ( OSPAR. 2000. op.. cit.) are partly convinced by these arguments although, as noted, the UK is taking a "greener" line than usual on this issue.

Although this discussion has been about SBMs, very similar arguments can be advanced when discussing disposal options for cuttings contaminated with WBMs. Almost universally, these are still dumped over the side after treatment which does not remove all the contaminants, including crude oil.

The Effects of Discharges of Drilling Fluid Additives

According to Patin, ferro-chrome lignosulfonate, a common drilling mud additive used as a thinner and deflocculant, has reported effects on survival and physiological responses of fish eggs and fry; the filtration control additive CMC (carboxy-methyl-cellulose) can cause death in fish fry at high concentrations (1,000-2,000mg/l) and physiological changes at 12-50 mg/l, whereas at the low concentrations (1-20mg/l) used in standard chronic tests it has no observed effects. Other additives used as defoamers, descalers, thinners, viscosifiers, lubricants, stabilisers, surfactants and corrosion inhibitors all have reported effects on marine organisms, ranging from minor physiological changes to reduced fertility, lower feeding rates and higher mortality, depending on the concentrations. Some of the corrosion inhibitors, for example phosphoxit-7, EKB-2-2 and EKB-6-2, are "characterised not only by high toxicity ... but by their ability to cause genetic and teratogenic damages as well (Petukhova, G. A., Tupitsina, L. S., Bulovatskaya, S. E. and Gerasimova, E. L. 1991. The Assessment of the Genetic Toxicity of Corrosion Inhibitors. In Theses of the Second All-Union Conference on Fisheries Toxicology,2: 97-98). Such properties were also revealed for a number of surface-active substances (surfactants) from a group of neonols - AF9-6, AF9-10, and others (Migalovski, I. P., Migalovskaya, V. N., Kosheleva, V. V. and Kasatkina, S. V. 1991. Impact of Surfactants on the Different Stages of Ontogeneses of Marine Fish under Experimental Conditions. In Theses of the Second All-Union Conference on Fisheries Toxicology, 1:46-48.)." [emphases added. JWGW.]

In 1995 Greenpeace published the following "typical analysis for heavy metal content of SOLTEX" [the commercial name of a common drilling fluid additive], which they had obtained from "a confidential source":

Table 6: Soltex components

Components of SOLTEX Concentration (mg/kg)
Antimony 6.0
Arsenic 0.4
Barium 16.0
Cadmium 0.6
Chromium (total) 1.2
Cobalt 2.0
Copper 1.3
Fluoride 200.0
Lead 3.0
Mercury 0.2
Nickel 11.0
Vanadium 16.0
Zinc 2.1

The SOLTEX in question was being used in relatively shallow waters in the Celtic Sea off the west coast of Britain, between Wales and Ireland. As Greenpeace explained:

"The exact chemical composition of many of the additives are closely guarded secrets by competitive manufacturers. In the recent exploration drilling off Pembrokeshire, Wales, the oil company Marathon discharged a total of 896 tonnes of drilling muds. Both Marathon and the Department of Trade and Industry only provided the trade name of chemicals. An example of how misleading this can be is with the additive known commercially as "SOLTEX". Marathon described SOLTEX as Lignite (non-asphaltic) and further described it under a common name as cellulose-based... Irrespective of the exact concentration of heavy metals, it is disturbing that the product can be described simply as cellulose based, with no reference made to the fact that it contains toxic substances." (Reddy, S., et al. 1995. op. cit)

Greenpeace listed dozens of other toxic and caustic additives, including the "particularly hazardous" arsenic, asbestos, compounds of chromium and zinc, organophosphates, potassium hydroxide and lead (a major ingredient of the "pipe dope" drillers use as a jointing compound in drill pipes).

SOLTEX is used as a shale control inhibitor with either WBM or OPF. It is also listed as an additive in the drilling muds (all apparently water-based) currently being used by Sakhalin Energy Investment Company at its Molikpaq platform offshore Sakhalin, in which Marathon is a partner and operator. Other Molikpaq additives to WBM, and their uses, are shown in the accompanying table.

Table 7: Additives used by SEIC at the Molikpaq platform

Sources: OCNS Lists; World Oil Tables

Name of substance, as given by SEIC Manufacturers named by OCNS List of Notified Chemicals or World Oil Tables Trade name As in OCNS List of Notified Chemicals or World Oil Tables FunctionUse in WBM or OBM?OCNS Group*
CF-Desco (CF Ligno)No entry in OCNS Appendix 1

Thinner/dispersant WBM ?
STAPLEX 500 (Glycol) M-I Drilling Fluids UK Limited Staplex 500 Shale Stabilizer C850 Shale stabilizer WBM E

Aubin Ltd Glycol-based GelShale stabilizer

IDF-FLR (Pac Reg.) M-I Drilling Fluids UK Limited IDF-FLR* C121 Viscosifier Either E
IDF-FLR-XL (Pac LV.) M-I Drilling Fluids UK Limited IDF-FLR* XL C122 Fluid loss additive Either E
SMX (Guar Gum) Baroid Ltd GUAR GUM Viscosifier for spud muds WBM E + PLONOR
IDVIS D (XC Polymer) Baroid Ltd XCD Polymer Viscosifier Either(?) E

M-I Drilling Fluids UK Limited Idvis* C124 Viscosifier


M-I Drilling Fluids UK Limited XC POLYMER "

Bicarb. of soda Baroid Ltd SODIUM BICARBONATE"

Soltex Drilling Specialities Company SOLTEX Shale control inhibitor Either D

Baroid LtdBarabrine Defoam "? A

BW Group plcBW Defoam Green"?E

BW Group plcBW Defoamer" ?C

M-I Drilling Fluids UK LimitedDefoamer C552"?E

Scotoil Chemical SystemsDefoam Green"? E
1. DUOVIS M-I Drilling Fluids UK Limited DUOVIS (Xanthan gum) Viscosifier Either E
2. "TACKLES" M-I Drilling Fluids TACKLE Liquid low M.W. polyacrylate WBM Not on OCNS list

It is noticeable that most are identified only by trade names, whereas the OSPAR list of substances which are either banned, subject to special regulation or whose discharge is considered to Pose Little Or No Risk to the environment (PLONOR) give only the generic or chemical names (OSPAR. 1999a. List of Substances / Preparations Used and Discharged Offshore Which Are Considered to Pose Little or No Risk to the Environment (PLONOR). 1999-9. Included as Appendix 12 to this report). This makes the information inaccessible to the general public. It takes an expert to decipher what is being used, why, and what its likely effects might be.

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Contact us if you have any questions or want to contribute an article:
Elena Pavlova webmaster@offshore-environment

"Muddied Waters":



List of Abbreviations

Summary of Conclusions

Drilling Waste Streams from Offshore Oil and Gas Installations

The Law on Offshore Wastes Discharges in Different Jurisdictions:

The OSPAR Convention

United Kingdom



United States

Inviting Regulation

Environmental Effects of Drilling Waste Discharges

The SBM Controversy

"Non-Water Quality Environmental Impacts"


Drill Cuttings

Produced Water

Minimising Waste Discharges and Their Effects

Reinjection Offshore

Cleaning Produced Waters

List of Main Sources

Selected References



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