Factors affecting the efficiency of well-killing fluids in fractured-porous carbonate reservoirs of the Eastern part of the Orenburgskoye oil-gas-condensate field

Background. At the Eastern part of the Orenburg oil and gas condensate field, which deals with abnormally low stratum pressure and high reservoir fracturing, special attention is given to controlling the absorption of technological well-killing compositions by a reservoir. Additional problems such as high gas-oil ratio (GOR) and high hydrogen sulphide content restrict the choice of blocking compositions and killing technologies. Standard methods for selecting blocking compositions do not allow one to identify effective well-killing technologies for the described conditions unambiguously. Identifying the blocking composition properties that influence the efficiency of well killing in complicated conditions of the Eastern part of the Orenburg oil and gas condensate field will help reduce the risks of accidents, increase the effectiveness of well-killing operations, and improve the project’s economic performance.

Aim. This work aimed to determine the main factors of laboratory studies which affect the efficiency of technological blocking compositions for killing wells in the conditions of the Eastern part of the Orenburg oil and gas condensate field.

Materials and methods. The laboratory analysis involved testing a range of blocking agents in conditions closest to reservoir ones. The physicochemical and rheological characteristics of blocking compositions were compared, as well as their effect on the productive properties of a formation. Laboratory tests were carried out on blocking compositions’ physicochemical, rheological and filtration characteristics.

Results. The results of laboratory and pilot tests were compared with the data about the primary blocking compositions appliance at the Orenburg oil and gas condensate field.

Conclusion. On the basis of the study, a hypothesis was put forward about the dependence of the killing wells blocking composition effectiveness in complicated conditions of the Orenburg oil and gas condensate field depends on its physical and chemical parameters, effective viscosity values and an indirect indicator of the composition strength.

1. Ovcharenko Yu.V., Gumerov R.R., Bazyrov I.Sh. Well killing specifics in conditions of fractured and porous carbonate reservoirs of the Eastern part of the Orenburgskoye oil-gas-condensate field. Oil Industry, 2017, no. 12, pp. 52–55 (In Russ.). https://doi.org/10.24887/0028-2448-2017-12-52-55

2. Karmushin S.R., Lezhnev K.E., Gumerov R.R., Bazyrov I.Sh., Gunkin A.S., Gvritishvili T.T. Estimating well killing fluid volume in the conditions of fractured porous reservoirs based on physical and mathematical modeling and statistical analysis. Oil industry, 2021, pp. 30–33 (In Russ.). https://doi.org/10.24887/00282448-2021-12-30-33

3. Gumerov R.R., Kunakova A.M. Improving the effectiveness of selection of blocking compositions for well killing with high gas factor and anomalously low unrecovered reservoir pressures in conditions of carbonate fractured-porous reservoirs. Oilfield Chemistry: Proceedings of the VI International Scientific and Practical Conference (xIV All-Russian Scientific and Practical Conference), Moscow, june 27, 2019. — Moscow, 2019, pp. 121–122.

4. Gumerov R.R., Karmushin S.R., Gvritishvili T.T., Sagirova L.R. Practical aspects of oilfield chemistry. Collection of abstracts of scientific and practical conference reports. Ufa, 2022, pp. 45–46.