Shari Dunn-Norman

Factors affecting CO 2 storage capacity and efficiency with water withdrawal in shallow saline aquifers

Carbon sequestration in shallow aquifers can be facilitated by water withdrawal. The factors that optimize the injection/withdrawal balance to minimize potential environmental impacts have been studied, including reservoir size, well pattern, injection rate, reservoir heterogeneity, anisotropy ratio, and permeability sequence. The effects of these factors on CO2 storage capacity and efficiency were studied using a compositional simulator Computer Modeling Group-General Equation of State Model, which modeled features including residual gas trapping, CO2 solubility, and mineralization reactions. Two terms, storage efficiency and CO2 relative breakthrough time, were introduced to better describe the problem. The simulation results show that simultaneous water withdrawal during CO2 injection greatly improves CO2 storage capacity and efficiency. A certain degree of heterogeneity or anisotropy benefits CO2 storage. A high injection rate favors storage capacity, but reduces the storage efficiency and CO2 breakthrough time, which in turn limits the total amount of CO2 injected.

Limiting Key Drilling Parameters to Avoid or Mitigate Mud Losses in the Hartha Formation, Rumaila Field, Iraq

Wells drilled in Rumaila field are highly susceptible to lost circulation problems when drilling through the Hartha formation. This paper presents an extended statistical work and sensitivity analysis models of lost circulation events in more than 100 wells drilled in Rumaila field. Lost circulation data are extracted from daily drilling reports, final reports, and technical reports. The volume loss model is conducted to predict the mud losses in the Hartha formation. Observations that are made from the volume loss model are ECD, MW, and Yp have a significant impact on lost circulation respectively; however, SPM, RPM, and ROP have a minor effect on the mud losses. Equivalent circulation density model is obtained to estimate ECD in the Hartha zone, and from this model can be deduced that MW, ROP, and Q have a significant impact on ECD respectively; nevertheless, RPM and Yp have a minor impact on the ECD. The rate of penetration model is made to estimate ROP in the Hatha zone. It is concluded that WOB, RPM, and SPM have a significant impact on the ROP respectively. Due to the lack of published studies for the Hartha formation, this work can serve as a practical resource for drilling through this formation.

Application of an Area of Review Variance Methodology to the San Juan Basin, New Mexico

When the Underground Injection Control (UIC) Regulations were promulgated in 1980, existing Class II Injection wells operating at the time were excluded from Area of Review (AOR) requirements. EPA has expressed its intent to revise the regulations to include the requirement for AORs for such wells, but it is expected that oil and gas producing states will be allowed to adopt a variance strategy for these wells. An AOR variance methodology has been developed under sponsorship of the American Petroleum institute 1 . The general concept of the variance methodology is a systematic evaluation of basic variance criteria that were agreed to by a Federal Advisory Committee. These criteria include absence of USDWs, lack of positive flow potential from the petroleum reservoir into the overlying USDWs, mitigating geological factors, and other evidence. The AOR variance methodology has been applied to oilfields in the San Juan Basin, New Mexico. This paper details results of these analyses, particularly with respect to the opportunity for variance for injection fields in the San Juan Basin.