‘Fizz water’ and low gas saturated reservoirs

Abstract

Numerous dry holes have been drilled based on false hydrocarbon indicators (DHI) and have been attributed to 'fizz water' effects. However, this 'fizz water' concept is illdefined and misunderstood. Newly measured data show that dissolved gas has negligible effect on water velocity. In addition, gas bubbles exsolving from either water or oil have only a small effect on fluid properties at pressures higher than about 20 Mpa (about 3000 Psi). Gas at high in situ pressure and temperature conditions has similar properties to light oil. Realistic gas properties must be used to estimate the properties of gas-liquid mixtures. Trapped original gas distribution in situ may be patchy (in layers or packets), while the exsolved or leaked gas distribution is likely to be relatively homogenous. Although fluid properties and gas distributions are complicated in deep-water reservoirs, seismic evaluation of gas saturation is possible. Developing seismic techniques to quantitatively calibrate hydrocarbon indicators in addition seismic evaluation of rock density and attenuation should lead to new integrated techniques for better evaluation of hydrocarbon saturation.

Mobility Effect on Poroelastic Seismic Signatures in Partially Saturated Rocks With Applications in Time‐Lapse Monitoring of a Heavy Oil Reservoir

“…Gas often exercises distinct influences on the compressibility of pore fluid mixture at shallow and deep reservoir environments (Han & Batzle, ). Consequently, the realistic elastic behavior of gas has also been accounted for the reservoir Models 1 and 2 (see Table ).…”

“…Many experimental works have examined the partial saturation effect on elastic properties of sedimentary rocks (Adam et al, ; Han & Batzle, ; Knight & Nolen‐Hoeksema, ; Murphy, ; Paffenholz & Burkhardt, ; Spencer & Shine, ; Winkler & Nur, ). Domenico () demonstrated that a few percent of gas saturation could cause a dramatic drop in P wave velocity.…”

Seismic Evidence for the Distribution and Migration of Fluids in Sedimentary Basins

“…Changes in seismic attributes can be affected by many factors; thus, the interpretation of fluid content directly from seismic anomalies is not always a unique solution. In some cases, hydrocarbon pools are detectable from seismic data; however, water containing limited amounts of gas can give seismic attributes of hydrocarbons similar to those of economic gas reservoirs, leading to many dry holes drilled on false prospects, known as the ‘fizz water’ effect (Han & Batzle 2002).…”

Estimation of reservoir properties from well logs and core plugs to reduce uncertainty in formation evaluation: a case study from the Kohat-Potwar Geologic Province

“…The solution of an inverse problem is not limited to a deterministic estimation of the solution which is supposed to be optimal in terms of best-fitting of the given dataset, but it also include the evaluation of the uncertainty of the inversion results. The improvement in reservoir characterization is very important to minimize the risk of drilled dry holes (Han and Batzle, 2002). This improvement is by the combine effort of wireline logs and core data with quantitative interpretation of wireline log data (Grana et al, 2012).…”