Surface Tilt Mapping (STM) has been successfully applied to stimulation treatments, disposal projects and in numerous steam floods to provide information on fluid movements in the reservoir. This proven technology has now been applied to a waterflood in the San Andres formation at a depth of 5600 feet to analyze preferential flow. Since typical water injection rates in the San Andres range from 100 to 300 BWPD, a novel flowback method was developed to maximize the STM response when testing injection wells under normal operating conditions. An analysis technique that allows the removal of earth tides was also applied to further enhance the quality of the data. The STM results showed conclusive preferential flow direction in the seven wells tested. In most wells, multiple tests were performed with good agreement on the flow trend.

Passive seismic imaging is a quickly growing technology to map fracture growth during hydraulic fracture stimulations, map active fracture networks, monitor well failures and track injection of fluid and steam. In this paper a number of issues are presented which should be considered when applying some potential applications are described, along with potential pitfalls that a potential user should consider.

Subsidence monitoring is most commonly conducted using either level surveys or GPS surveys of elevation monuments to determine changes in elevation across a field as a result of injection and production activities. Several operators near Bakersfield, CA are using tiltmeter-based subsidence monitoring to obtain highly detailed maps of subsidence with continuous data acquisition. The tiltmeter measured subsidence is then correlated to production and injection on a day-by-day basis so the impact of individual injection and production events can be quantified. The data is presented in a video format that allows visual assessment of the field motion. In some fields, the monitoring array is also equipped with monuments for periodic level survey and GPS measurements of the ground motion.

This paper discusses the design and installation of tiltmeter subsidence monitoring arrays and the format of the results. In addition, the subsidence data is correlated to field activities to show how the monitoring can be used to correlate ground movement with reservoir events.

In secondary and enhanced oil recovery projects, it is critical to determine if hydraulic fracturing occurs during water injection and, if fracturing occurs, to understand its associated impacts on oil recovery. If hydraulic fracturing occurs under normal injection operating conditions or, if the production and/or injection wells are fracture stimulated, knowing the orientation and dimensions of the created fractures are critical for determining the proper pattern alignment to optimize sweep efficiency. This paper presents the application and results of tiltmeter mapping techniques used at the Howard Glasscock East Unit (HGEU). Tiltmeter mapping was used to determine the existence, orientation, and geometry of created hydraulic fractures, as well as, the dependence of fracture length on the water injection rate. Tiltmeter fracture mapping identified that hydraulic fracturing occurs even at very low water injection rates (less than 250 BWPD) at the HGEU creating significant fractures (exceeding 400 feet of half-length). The mapping also showed that the length of the fractures was relatively rate independent over the range of rates tested. The HGEU waterflood pattern orientation, pattern spacing and injection rate guidelines were established based on these results.