b'Seismic window Seismic windowTable 1.Relationships among elastic constants in an isotropic material (from Mavko etal. 1998). From left to right Bulk Modulus (reciprocal of compressibility), Youngs Modulus, incompressibility, Poissons ratio, P wave modulus, shear modulus.Michael Micenko Associate Editor for Petroleummick@freogeos.com.auInversion and HMPAThis article is about two techniques that were brought to my attention while I was networking late last year in two completely different venues. The first wasseveral years, could produce both theis no response to gas, but oil and water at a traditional event with a few beers afterP velocity and S velocity and in somehave a distinct but different signal. They work, while the second was in a moderncases density. Once these attributes aredescribe HMPA as a black box technology, but less fun venue called LinkedIn. Iknown, the Lames parameters (and)which means the workings are secret, or have always found networking to be ancan be calculated. Then, any of the rockthey dont know why it works.important aspect of keeping abreast withproperties shown Table 1 can be obtained. technology and trends, and even thoughAt last years networking function I learntMaybe it does work as advertised, but for LinkedIn has no physical networking it stillthat pre-stack inversion can outputnow its well and truly placed in my funny manages to disseminate ideas. compressibility directly, thereby savingmethods file. Figure 1 shows an example computer time and two-three weeks in theHMPA map showing a linear, channel like Inversion for compressibility interpretation cycle. Another advantage isanomaly with dry holes at the edge and a that the derived products are three timesdiscovery well in the centre of a feature.The first technique is to calculate rockmore sensitive to changes compared to properties such as compressibility usingAVO products such as V P /V S.But, perhaps seismic inversion. Compressibility isthe most benefit is obtained by providing the relative change in rock volume inengineers data in a form with which they response to a pressure change. It is aare familiarphysical rock properties useful rock property and can be used to: rather than geophysical conveniences.estimate changes in pore volume as reservoir pressure declines withHMPA (Hydrocarbon Modulated production Pulse Analysis)to distinguish between low porosity and high porosity rocks I noticed this technology on LinkedIn identify gas filled sands and thought Id dive in and try to understandit. HMPA is interesting for two Seismic amplitudes only containreasonsfirst, it claims to respond best to information on P velocity, S velocity,the thickest oil saturated reservoir section, density and anisotropy, but otherwhich would make it an extremely useful attributes can be derived once the Ptool and second, its description lacksFigure 1.Example HMPA map showing a linear and S velocities and density are known.any useful information. This potentiallyanomaly interpreted as a channel with dry holes Seismic inversion has come a long wayuseful tool is described only as measuringoutside the feature and production well in the centre. since I first encountered it in the 1980s.specific electrical signatures createdHMPA is an electrical technology that does not Back then it was a post stack process andwhen hydrocarbon energy is convertedidentify structure it identifies oil reservoirs at depth.the deliverable was a pseudo-seismicto electrical energy through a complex impedance log at each trace. We thoughtseries of chemical processes at reservoirReferenceit was the bees knees. But there wasdepth. Thats a lot of words, but it tells more information to be extracted andme nothing except perhaps that theMavko, G., Mukerji, T., and Dvorkin, J., simultaneous inversion using pre- reservoir is behaving like a battery. The1998. The Rock Physics Handbook. stack data, which has been around forpromoters of the technique claim thereCambridge University Press.FEBRUARY 2022 PREVIEW 36'