Introduction

The University of Kansas and the Kansas Geological Survey have been a university partner with Landmark Graphics for the last year and a half. Over that period we have focused our efforts in three areas: 1) research, 2) technology transfer to industry, and 3) education of students. Our research efforts have been directed at what could be considered non-traditional applications of the Landmark computer workstation. At this year's Landmark Technology Symposium we presented three papers that emphasized this approach. These papers dealt specifically with application of central difference operators to post stack spectral shaping (John Hopkins and others), use of the Landmark system for environmental applications (Alex Martinez and others) and a seismic approach to wireline logs (Carr and others). This manuscript is adapted from the last of those three presentations. The work to develop a seismic approach to petrophysical sequence stratigraphy is being carried by a number of individuals at Kansas, but is the current focus of Ph.D. research of one of the co-authors of the presentation, John Hopkins. It should be emphasized that this is a report on an area that is rapidly progressing, and in a strict sense it is not a how-to paper. We believe that the seismic approach to petrophysical sequence stratigraphy has the potential to change the geologist's traditional well-by-well approach, and improve integration of geologic and geophysical data through integration of methodologies.

The genesis of the seismic approach to wireline logs arose from our efforts to use the computer workstation to integrate geologic and geophysical approaches to subsurface analysis, and the frustration of working in mature producing areas of the Midcontinent and Kansas that are dominated by areally extensive subtle traps. Since initial production in 1889, approximately 300,000 wells have been drilled in Kansas. Even today new fields, pools, extensions, bypassed pay, and infield opportunities are realized on regular basis. As an example, over the last decade the area of southwest Kansas known as the Hugoton embayment has experienced significant increases in both oil and gas production. The frustration is a result of trying to apply computer aided exploration and development techniques to a large field or a basin such as the Hugoton embayment. The Hugoton Embayment covers approximately 12,000 square miles and contains over 12,000 producing oil and gas wells. The Hugoton Gas Field alone which dominates the area contains almost 6,000 producing wells and covers over 4,000 square miles.

How does one undertake a comprehensive, cost effective and timely field study or basin analysis of such beasts? How can we effectively leverage the large existing database of well data? These are questions that are not unique to Kansas but are typical of any large field or producing region. Given the size of the areas and the shallow drilling depths and the subtle nature of the traps (3,000 to 5,000 feet in the case of the Hugoton) large scale 3-D seismic surveys are in many cases difficult to justify by the geophysicist on both technical and economic criteria. The geologist with a traditional well-by-well approach to stratigraphic interpretation is swamped with well data. Even assisted by computer programs such as Stratworks the challenge of examining 12,000 wells can be viewed as intractable or as long-term job security. Assuming an average of one hour to pick tops, analysis reservoir parameters, and correlate each well one is looking at over 6 work-years to examine only the producing wells in the Hugoton. The logical result is that truly comprehensive basin analysis of the Hugoton Embayment or comprehensive field studies of such large fields as Hugoton or Panoma gas fields of Kansas do not exist. Out of necessity previous studies have been severely limited in either area or scope. It is our belief that an understanding of the basin or field as a whole would increase the probability of efficient exploitation of significant resources such as the mature producing areas of Kansas.