Abstract

Crosswell seismic is a powerful reservoir imaging tool that can help solve many developmental and production problems especially in complex and mature reservoirs. Each survey is carefully designed, considering (i) the objective or the problem to be solved, (ii) the geophysical issues, and (iii) the operational issues.

The starting point for designing a crosswell survey is a clear understanding of the objective; for example to image faulted compartmentalization for identifying bypassed pay or monitor a flood front to optimize injection arrangement.

Based on the imaging objectives defined above, pre-survey modeling and design can be done to optimize the data acquisition while assuring adequate coverage of the target area. Geophysical issues such as: where the energy is going to focus or cover given the wellbore geometry and formation dip can be anticipated with 3-D pre-survey modeling.

Crosswell equipment, acquisition and data processing provide reliable performance at 80-acre well spacing and greater distances in areas such as the ChevronTexaco Property in Lea County, New Mexico. Closely spaced wells typical of CO₂ and steam flood projects are ideal candidates for efficient crosswell seismic tracking of CO₂ and steam to aid in the understanding and improvement in flood performance. Given the complex nature of West Texas reservoirs, in-fill and horizontal drilling opportunities are abundant. With proper survey planning, acquisition and processing full value of the crosswell service can be realized to improve field-wide performance.

Specific data acquisition strategy and results from the ChevronTexaco Lea County, New Mexico Vacuum Wolfcamp property will be discussed in the body of this paper.