Advantages of joint interpretation of P-P and P-SV seismic data in geothermal exploration

Abstract

Conventional P-P seismic images of geothermal reservoirs are often of poor quality because P-P data tend to have a low signal-to-noise ratio across geothermal prospects. Fracture identification, fluid prediction, and imaging inside subsurface areas influenced by superheated fluids are some of the challenges facing the geothermal industry. We showed that multicomponent seismic technology is effective for addressing all of these challenges across geothermal reservoirs, even when P-P data are of low quality. Although multicomponent seismic technology has advantages in geothermal exploration, there are not many published examples of multicomponent seismic data being used to characterize geothermal reservoirs. We evaluated data examples that illustrate advantages of multicomponent seismic technology for imaging within and below zones having superheated fluids, estimating fracture attributes, analyzing reservoir trapping structures, differentiating lithologies, and predicting spatial distributions of pore fluids. All examples we tested are from the Wister geothermal field in Southern California. IntroductionConventional P-wave (P-P) seismic technology often does not provide information that engineers need to optimize geothermal energy production, usually because P-P data have a low signal-to-noise ratio (S/N) in numerous geothermal environments. The reasons why P-P data have low S/N values across geothermal systems vary from prospect to prospect, but common causes are complex faulting, high attenuation of P-waves in zones having concentrations of superheated fluids in rock pores, and dramatic lateral variations in P-wave velocities in geothermal strata.Joint interpretations of P-wave and S-wave data across oil and gas prospects provide more information about subsurface structures, lithology distributions, and pore-fluid saturants than do interpretations of only P-P data (Stewart, 2010). Fundamentally, S-wave seismic data have equal value to P-wave data in geologic interpretations, which leads to the conclusion that seismic stratigraphy analyses in any geologic province should be based on joint interpretations of P and S data rather than restricting interpretation to only single-component P-wave data (Hardage et al., 2011). Our reason for publishing this work is to provide a case history that emphasizes the importance of joint interpretations of P and S data across geothermal areas. Our study uses 3D converted-S (P-SV) data acquired at Wister geothermal

Geothermal Resource Exploration in Reshi Town by Integrated Geophysical Methods

“…The junction point and curve asymmetry indicate the presence and form of the lowresistivity body. The joint profile technique offers notable benefits such as high resolution and clear identification of low resistance anomalies, making it the optimal approach for detecting and tracking well-conductive steep structures [27,28]. The joint profile technique offers notable benefits such as high resolution and clear identification of low resistance anomalies, making it the optimal approach for detecting and tracking well-conductive steep structures [27,28].…”

“…The joint profile technique offers notable benefits such as high resolution and clear identification of low resistance anomalies, making it the optimal approach for detecting and tracking well-conductive steep structures [27,28]. The joint profile technique offers notable benefits such as high resolution and clear identification of low resistance anomalies, making it the optimal approach for detecting and tracking well-conductive steep structures [27,28]. In the field, electric leakage inspections were performed before, during, and after work to ensure that the wires did not leak electricity.…”

Resistivity and density estimation from multicomponent seismic data: Case study from the Lower Cretaceous McMurray Formation, Athabasca Oil Sands

“…The variation in PP and PS seismic data result from the fact that each type of reflection is controlled by different elastic properties of the medium, some associated with the rock matrix, and some associated with the fluid present in the rock pores (Wei et al, 2014). It is possible that combining the two types of data can reveal the stratigraphic architecture and a better understanding of the reservoir.…”

Advanced seismic processing/imaging techniques and their potential for geothermal exploration

“…Steam introduces higher absorption of the seismic wavefield and also has the effect of decreasing the seismic velocity. Wei et al (2014aWei et al ( , 2014b show the benefits of using multicomponent seismic data in the Wister geothermal field, which is a Cenozoic sedimentary basin located in California. The goal of their study was to evaluate potential reservoir units, locate fault, and fracture zones and investigate whether additional value can be gained from multicomponent seismic data.…”

“…Seismic section that illustrates (a and b) differences between P-P and P-SV stacks within gas clouds marked by black ovals and (c and d) across a region with low saturation of high-temperature fluid indicated with a yellow rectangle. Note that P-SV data contain more amplitude information within gas clouds and fluid-filled regions compared with P-P data (modified from Wei et al, 2014a). of the overburden layer.…”