A Set of Options for Stimulation of Wells

Abstract

The most effective well interventions employed by Shehsmaoil Management Company LLC (Republic of Tatarstan, Russia) are the following [1-4]: – hydraulic fracturing (HF), – forced gas extraction unit from a wellbore annulus. The article addresses the issues of increasing recoverable reserves of oil, oil recovery factor, speeding up development, improving the profitability of deposits and fields (with carbonate deposits) as a whole through the introduction of proppant fracturing technology (PHF), multistage fracturing in wells with horizontal endings, drilling a compact grid of wells with subsequent fracturing. It is indicated that optimization of PHF (transition to hybrid hydraulic fracturing) by combining low-viscosity and cross-linked fluids depending on the performance during test injections made it possible to stabilize product's water cut, increase well productivity in terms of oil and stabilize oil recovery reduction rate. All relevant operations are implemented by three functioning hydraulic fracturing fleets operated that uses the equipment mounted on all-terrain chassis. The paper reviews and summarizes the application results of various fracturing fluid systems: borate-crosslinked guar fluids, Bioxan modified natural polysaccharide, fluids based on fresh water or viscoelastic surfactants, guar-free low-viscosity and high-viscosity water-based polymer systems, synthetic gelling agent. All the described systems feature the required sand trapping properties, so it is the price of the systems that determines the best choice. The article considers a portable set of equipment for forced extraction of gas from the wellbore annulus and its subsequent pumping into the oil pipeline by means of gas extraction sets of the KOGS type. In the conditions of shallow fields with hard-to-recover reserves the Company specialists encounter the challenge of increasing the profitability of development. The main reserves of the fields under consideration are confined to carbonate targets, and the reserves of deposits of the Kizelovsky gorizont of the Tournaisian stage occupy a considerable place by their quantity. Development of this object is mainly complicated by the following factors: complex geological structure, viscous, heavy and resinous oil, low reservoir temperatures and pressures. For the reasons of low efficiency of classical development systems, systems of reservoir pressure increase, it is necessary to develop, test, introduce new methods of intensification, new elements of development - compaction of well grid, horizontal wells (HW) with the following multistage fracturing. The fields considered in the article are tectonically controlled by the Western slope of South Tatar arch and Eastern edge of Melekesskaya depression, territorially located in Tatarstan.