Today, when most reservoirs have low productivity, the question of whether hydraulic fracturing can be applied to the oil rims becomes very important. During hydraulic fracturing at Novoportovskoe field, the operator was faced with a complex geological model of the reservoir characterized by an absence of strong barriers and minor contrasts in stress between interlayers associated with high risks of breakthrough into the gas zone. An outstanding example of oil rim stimulation and application of new technology was a project in Novoportovskoe field where 30- and 27- stage multistage fracturing operations (MSF) were successfully performed with a shifting ports completion operated by coiled tubing.
Currently, oil and gas companies are increasingly demanding technical and technological aspects of the MSF, where the determining factors are the efficiency of operations, the number of stages, the length of the horizontal part of the well, the possibility of refracturing, and ability to open / close sleeves after operation for water and gas shut-off. The experience gained shows the possibilities of modern technologies, where the use of coiled tubing enables meeting the high requirements and also expanding the boundaries of the application. The 30-stage boundary was successfully overcome and allowed to increase the formation coverage by means of more fracturing stages. At the same time, the completion method made it possible to perform MSF without pulling the coiled tubing out of hole and to use all the capabilities and benefits of CT in the case of a screenout (SO).
The teamwork between the customer and several of the contractor's product lines enabled successful completion of the integrated project under the difficult geological and climatic conditions of the Novoportovskoe field, which is located beyond the Arctic Circle. An optimized concept of MSF with the use of re-closable full-pass hydraulic fracturing sleeves, operated by a single-trip coiled tubing-conveyed shifting tool was developed and implemented.
The following results were achieved:
In one week, 57 hydraulic fracturing stages were completed.
Hydraulic fracturing stage time was reduced by 63%.
The number of stages per well increased by 43%.
The gas factor for storage was reduced from that of previous fracturing operations.
The integrated method of multi-stage hydraulic fracturing allowed achieving effective fracture coverage to increase the recoverable reserves, while preventing fractures in the gas cap and bottom water.
The sliding sleeves MSF technology, operated by coiled tubing without pulling it out of hole, is applicable to further operations in the region and worldwide. This paper describes the experience, lessons learned, and best practices gained at the Novoportovskoe field while deploying a novel application of MSF for oil rim deposits where CT was used as the key enabler. It also describes the first success worldwide in closing of sleeves after 1 year of well production. The well was completed in December 2017 with a 30-stages, and in 2018, after a year of production, logging showed a gas break through which required eight sleeves to be closed. All eight sleeves were successfully closed. This method can be applied to other oil and gas fields, where the construction of horizontal wells with MSF is the main development strategy.