Ph.D. Theses

Development and application of new methods for stimulation of non-newtonian oil production based on diagnosing bottomhole zone status

Keldibayeva Svetlana Syrlybayevna

2525.01 - Development and exploitation of oil and gas fields

One of the priority tasks in Kazakhstan oil industry at the present stage of its development is stimulation of hydrocarbon production in the developed and equipped fields at a late development stage containing significant residual oil reserves.

The thesis proposes a statistical modeling method of an oil field, based on which the development stages and their duration were identified for the 13th horizon of the Uzen deposit, and a forecast of initial recoverable reserves was made.

Analysis of enhanced oil recovery in Kazakhstan fields revealed that hydrofracturing is the most effective method with a 75% success rate. A new criterion for selecting candidate wells based on an analysis of the oil content variation from fluid extraction has been developed to increase the success rate. Application of the developed criterion allows increase of success rate up to 95-98%.

Based on the studies, a composition for the removal of ARPD (asphaltene-resin-paraffin deposits) including a hydrocarbon solvent and an additive has been developed. The efficiency of ARPD removal using the obtained compositions at various deposits varies within the range of 84.4-97.6%. It has been established that the developed composition for ARPD removal is at the same time effective oil thinner enabling to update flow curves, when the nonNewtonian oil becomes Newtonian due to the addition of the composition.

A new enhanced oil recovery method has been developed to improve the efficiency of microbiological stimulation method, when a low salinity water fringe of 30% of the pore volume is created prior to organic substrate injection. As an organic substrate, a 10-15% solution of cheese whey and milk whey is used in low salinity water in a 75:25 ratio. At the same time, the oil displacement ratio will be 74%.

The developed technologies have been successfully tested at the Uzen field. On the basis of the proposed criterion, 12 wells were selected for hydraulic fracturing and 25025 tons of incremental oil was produced, the success rate was 98%.

Introduction of the developed microbiological stimulation method on pilot sites, including eight five- and seven-point elements, resulted in the cumulative 47468 tons of incremental oil production for the year.

Total additional oil production in the result of implemented measures run to 72493 tons.