Formation Damage Prevention by Using an Oil-Based Fracturing Fluid in Partially Depleted Oil Reservoirs of Western Siberia

Abstract

Comparing with water-based fluids, oil-based fracturing fluid is not in wide use. The main reasons are lower cost effectiveness and more dangerous handling of oil-based fluid. However, as non damaging fracturing fluid, the oil-based fluid has numerous advantages over water-based. In fact, in many cases, where water-based fluid failed, switching to oil-based fluid resulted with successful stimulation of well productivity. One of such cases is fracturing of partially depleted oil reservoirs of Bakhilov and North Khokhryakov fields in Western Siberia, Russian Federation. The oil fields were discovered in 1983. Production started in 1987 and water injection began in 1988. The peak oil production was reached in 1991/92, followed by drop of 50%. An attempt was made to increase wells productivity by performing small hydraulic fracturing treatment using water- based fluid. Although it resulted in some increase in wells productivity, the analysis of that treatments suggested necessity for longer fractures and careful tailoring of fracturing fluid. Recently the twenty-three fracture treatments have been performed using an oil-based fracturing fluid and pumping significantly higher quantity of proppant. The result is excellent: nearly all wells started to flow at the average initial oil rate of 70 m3/day [440 bopd] what is more than ten-folds production increase in comparison with pre-fracture production. Comparison of median values of early and late post-fracture production indicates sustained productivity improvement. P. 121

Multiphase Multicomponent Numerical Modeling for Hydraulic Fracturing with N-Heptane for Efficient Stimulation in a Tight Gas Reservoir of Germany

“…At this point, it is important to address the economic considerations regarding the field application of n-heptane (or light alkanes) as a frac-fluid. Studies for the application of hydrocarbon-based fluids have demonstrated economically attractive prospects and shown that comparable or even lower costs will be incurred in comparison with waterbased fluids due to lower well cleanup requirements, better flowback ability, less additives, injection fluid flowback, reuse or sale, no special disposal requirements, and increased productivity [22,[55][56][57][58][59][60]. Moreover, unlike gas-based hydrocarbon fluids such as LPG, there is no need for compression for liquification for the fluid reuse [61].…”

Completion Operations in Low Permeability Deep Basin Gas Reservoirs: To Use or Not to Use Aqueous Fluids, That is the Question

“…Hydrocarbon-based fluids generally can be sold to the market; 2) It appears that the residue resulting from water-soluble polymers used with aqueous fracturing fluids may be more damaging to the formation and to the fracture conductivity compared to hydrocarbon-based fracture fluids (14) ; and, 3) A hydrocarbon-based fluid can be cleaned up quicker and with less swabbing compared to aqueous-based fluids resulting in operational cost savings (14,25) . Hydrocarbon-based fluids generally can be sold to the market; 2) It appears that the residue resulting from water-soluble polymers used with aqueous fracturing fluids may be more damaging to the formation and to the fracture conductivity compared to hydrocarbon-based fracture fluids (14) ; and, 3) A hydrocarbon-based fluid can be cleaned up quicker and with less swabbing compared to aqueous-based fluids resulting in operational cost savings (14,25) .…”

“…The clean-up can be a very slow process in tight and/or depleted reservoirs (9,(13)(14)(15)(16) . Furthermore, the process of evaporation is much slower in tighter rocks (9)(10)(11)(12) .…”