ISSN 1070-4272, Russian Journal of Applied Chemistry, 2016, Vol. 89, No. 7, pp. 1145−1157. © Pleiades Publishing, Ltd., 2016.
The text was submitted by the authors in English.
Scaling phenomena is widespread in the process of
oil exploitation, water injection, and the drainage. It
will reduce oil recovery, corroding pipeline equipment,
and cause huge economic losses [1–5]. Among scales,
sulfate scale, especially barium sulfate scale, is much
more difﬁ cult to remove than carbonate scale because
of its high hardness, low solubility, compact crystal
structure, and other features [6–9]. Sulfate scale will
generate great ﬁ nancial loss and bring potential safety
hazard to construction site and worse, it will cause
a serious threat to the natural environment [10–12].
Frenier  pointed out that the ﬁ nancial loss of the
US oil industry caused by scaling was estimated to be
$1.4 billion a year. So it is very necessary to control
barium sulfate scale  and descale in the oil gather-
ing and transferring system.
In fact, scale samples collected in the injection
wells include all kinds of inorganic and organic matter.
Inorganic scale is also called oilfield scale because
it is more typical in the oil field. Oilfield scale are
widespread in the water injection system and pipeline
of oil ﬁ eld. A main cause of its formation consists in the
fact that complexation of ions gives substances which
are insoluble, difﬁ cult to dissolve and slightly soluble in
water. These substances can easily end with a thick scale,
namely salt scale. Because of the water quality, this kind
of scale is generally composed of carbonate and sulfate,
calcium carbonate, such as calcium sulfate, barium
sulfate, strontium sulfate, etc. The formation of the scale
usually goes through the process of nucleation growing
up, that is, forming some scale cores and attaching at the
Preparation and Performance Evaluation of a Highly Effective
Barium Sulfate Descaling System
Based on Ammonium Carboxy Chelating Agent DTPA
*, Xu Yang
, Jianlan Yuan
, Li Guo
, Xiaoling Wu
, and Hao Wang
School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, Sichuan, 610500 China
State Key Laboratory of University, Southwest Petroleum University, Chengdu, China
CNOOC Energy Technology & Services-Shanghai Oilﬁ eld Technology Services Branch, Tianjing, China
Received April 13, 2016
Abstract—In drilling and production process, the barite powder serving as weighting agent is added to ensure
operation safety when overﬂ ow occurs, that results in reservoir pollution and pore blockage. The main component
of barite is BaSO
, so ammonium carboxy chelating agents can be injected into formation to form stable chelates
will be eliminated from wellbore with ﬂ owback ﬂ uid easily. In this experiment, the weight
method and the atomic absorption spectrometry method were utilized to study descaling ability and an action
mechanism of descaling agents. Firstly, DTPA was selected from three descaling agents: NTA, EDTA, DTPA; then
OT1 was screened out to synergize with DTPA and studied its descaling mechanism; eventually, the descaling
system STD was determined, and its composition was 6% DTPA + 5% OT1 + 1% antiswelling agent + 100 ppm
corrosion inhibitor. And the STD’s performance evaluation experiment results suggested that it had an excellent
resistance to temperature and demonstrated a good descaling ability at 170°C. Furthermore, the descaling ability
of STD was almost not affected by calcium and magnesium ions and its corrsion rate is lower than standard value.
Moreover, STD could descale efﬁ ciently at lower dosage. So STD can be widely applied to descale in oilﬁ eld.