Surgil ESIA Report - Volume III - EKN

“Management of Ustyurt GCC infrastructure objects
and Surgil GCF construction” UE »
1. INTRODUCTION
1.1. Oil and gas wells drilling is connected with formation of considerable volumes of wastes to
which concern drilling mud, drilling cuttings or drilling rock, drilling mud-polluted drilling sewage
wastes, chemical reagents, oil products. Chemical reagents in the drilling mud, containing in the
structure a broad spectrum of the mineral and organic nature substances, can impact on the biosphere
objects during their ingress in environment.
1.2. Drilling mud carry out various functions: washout, drilling rock lifting, heat removal from chisel,
maintenance of wells walls integrity, lessening of drill pipes friction on well walls, etc. One of
the basic components of any drilling mud is always bentonite (Montmorillonite clay). Effect of this
component is explained by features of its physical and chemical nature, interaction with the disperse
medium with formation of stable colloid system in it.
1.3. Surface-active substance (SAS) concern to the reagents decreasing surface tension on threephase
border "layer-water-oil". Main purpose of SAS is maintenance of the collectors’ natural permeability.
Their penetration into drilling mud sharply reduces wells productivity and considerably
extends their adaptation terms. There are used various substances as SAS: sulfanole, disolvane, carbozoline,
stearox, azolyte and various oxy-ethylated spirits. Imperfection of SAS is their intensive
adsorption at solid phase of drilling mud and also intensive foaming.
1.4. There are uses reagents-defoaming for degassing of the drilling mud: soastoc, carbolineum, fusel
oil, polymethylsilosales, solid oil, synthetic fatty acids, etc. There are uses reagents- fluid loss
reducer for drilling mud quality maintenance (coal-alkali reagent, carboxymethyl cellulose, condensed
the sulfite-spirit slop, hydrolyzed polyacrylimide) and thinning agents (ferrochrome lignosulfonate,
nitrolignin, sunil, igetane).
1.5. Besides, there are applied: thermal stabilizers, amendments, lubricant additives, emulsifying
agents and other components. There is applied caustic soda all over the world as practically unique
reagent – alkalinity controller. Caustic soda (NaOH) is colorless crystal mass, well water-soluble
with large quantity heat release. Small alkali additives cause temporary clay particles dispersion,
electrokinetic potential increase and, as consequence of it, decrease in drilling mud viscosity and
fluid loss.
1.6. Apparently from the aforesaid, drilling mud toxicity level depends on presence in its composition
of the various organic and mineral components added in mud for giving to it those or other
properties demanded at drilling. Drilling cuttings and drilling sewage waters acquire toxicity owing
to contact with drilling mud. During ingress in environment the drilling mud and drilling cuttings
cause local changes of the ecosystems chemical and biological parameters.
1.7. This Management Procedure is developed for drilling wastes recycling during production wells
construction in Surgil field and corresponds to uniform rules and requirements producible by laws
of the Republic of Uzbekistan, and also to the international rules in relation to environmental protection
during overland wells drilling, to their moving, warehousing and drilling wastes storage.
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