APPLICATION OF AN AREA OF REVIEW VARIANCE METHODOLOGY TO THE SAN JUAN BASIN OF NEW MEXICO Prepared for the American Petroleum Institute by the University of Missouri-Rolla School of Mines and Metallurgy Dr. Don L. Warner Dr. Leonard F. Koederitz Dr. Shari Dunn-Norman Dr. Robert C. Laudon Rolla, Missouri December 1995 TABLE OF CONTENTS 1 .o Summary and Conclusions 2.0 Introduction 3.0 Area of Review Variance Methodology 4.0 Application of Area of Review VarianceMethodology to the San Juan Basin 4.1 Geological Description of the Basin 4.1.1 Structure 4.1.2 Stratigraphy 4.1.2.1 Oil and Cas Horizons 4.1.2.2USDWs 4.1.2.3 Confining Beds and Sloughing Zones 4.1.3 Geologic History 4.2 Basin Exploration and Development History 4.3 Regulatory and Statutory History 4.3.1 Evolution of the State Regulatory Body 4.3.2 State Regulations - Well Construction and Abandonment 4.3.3 Well Construction and Abandonment Standards 4.4 Basin Pressure Study 4.4.1 Method of Constructing Petroleum Reservoir Head Maps 4.4.2 Method of Constructing USDW Head Maps 4.4.3 Method of Constructing Residual Maps 4.4.4 Interpretation of Results 4.4.5 Effects of Injection within Mesaverde Negative Residual Area 4.5 Evaluation of Well Construction and Abandonment Characteristics 4.5.1 Identification of Sub-areas 4.5.2 Area Sampling Technique(s) 4.5.2.1Abandoned Wells 4.5.2.2 Active Wells 4.5.3 Preparation of Well Construction and Abandonment Diagrams 4.5.4 Western Area Results 4.5.4.1 Injection Fields 4.5.4.1.1Horseshoe 4.5.4.1.2 Many Rocks 4.5.4.1.3 Many Rocks, North 4.5.4.1..4Mesa 4.5.4.1.5Rattlesnake 4.5.4.1.6 Tocito Dome, N. .. 11 .' 4.5.4.2.Western Area Well Constructionand Abandonment Methods 4.5.4.2.1 Deep Wells 4.5.4.2.2 Shallow Wells 4.5.4.3 Western Area Summary 4.5.5 Southern Area Results 4.5.5.1 Injection Fields 4.5.5.1.1Chaco Wash 4.5.5.1.2Hospah 4.5.5.1.3Hospah, South 4.5.5.1.4 Lone Pine 4.5.5.1.5 Miguel Creek 4.5.5.1.6 Red Mountain 4.5.5.2. Southern Area Well Construction and Abandonment Methods 4.5.5.3 Southern Area Summary 4.5.6 Interior I Area Results 4.5.6.1 Injection Fields 4.5.6.1.1 Media 4.5.6.1.2 Papers Wash 4.5.6.1.3San Luis 4.5.6.2. Interior I Area Well Construction and Abandonment Methods 4.5.6.3 Interior I Area Summary 4.5.7 Interior II Area Results 4.5.7.1 Injection Fields 4.5.7.1.1Bisti 4.5.7.1.2Blanco, S. 4.5.7.1.3 Cha Cha 4.5.7.1.4Escrito 4.5.7.1.5 La Plata 4.5.7.1.6 Puerto Chiquito, East 4.5.7.1.7 Puerto Chiquito, West 4.5.7.1.8 Rio Puerco 4.5.7.1.9Totah 4.5.7.2. Interior II Area Well Construction and Abandonment Methods 4.5.7.3 Interior II Area Summary 4.5.8.Basin Summary References Tables Figures iii LIST OF TABLES Table Number 1 Field Listing for New Mexico (with location and discovery date) 2 1990 Well Construction and Abandonment Regulations 3 Oil Well DST Pressure Data Converted to Heads 4 Oil Wells Common to Fields used for Head Contouring 5 Initial and Edited Data Points for Petroleum Reservoirs and USDWs 6 Latitude, Longitude and Elevationsfor all USDW Data 7 Injection Well Locations and Heads Converted from Pressures 8 Oil and Gas Fields by Basin Sub-area 9 Western Area Field Summary - Deep Wells Only 10 Western Area Field Summary- Shallow Wells Only 11 Western Area Well Count Summary 12 Western Area ABE Results 13 Southern Area Field Summary 14 Southern Area Well Count Summary 15 Southern Area ABE Results 16 Interior I Area Field Summary 17 Interior I Area Well Count Summary 18 Interior I Area ABE Results 19 Interior II Area Field Summary 20 Interior II Area Well Count Summary 21 Interior II Area ABE Results 22 Summary Results of Application of AOR Variance Criteriato San Juan Basin Injection Fields iv LIST OF FIGURES Fieure Number -Title 1 AOR Evaluation Methodology 2 Outline of San Juan Basin 3 Structural Elements of the San Juan Basin 4 Generalized Hydrogeologic Cross-section of the San Juan Basin 5 Generalized Stratigraphy of the San Juan Basin 6 Stratigraphic Cross-section of Upper Cretaceous Rocks 7 New Field Discoveries 8 NMOCD Districts 9 Milestone Timeline of Oil and Gas Regulations 10 San Juan Basin Current Well Construction Practices 11 San Juan Basin Current Well Abandonment Practices 12 Formation Groupings for Petroleum Reservoir Head Maps 13 Injection Field Locations and Basin Sub-Area Plat 14 Example Dwight's Well Report (example with data) 15 Example Dwight's Well Report (example without data) 16 Example State Report (earliestform) 17 Example State Completion Report 18 Example State Abandonment Report 19 Western Area Deep Well Construction Configurations 20 Western Area Deep Well Abandonment Configurations 21 Western Area Shallow Well Construction Configurations 22 Western Area Shallow Well Abandonment Configurations 23 Southern Area Well Construction Configurations 24 Southern Area Well Abandonment Configurations 25 Interior i Well Construction Configurations 26 Interior I Well Abandonment Configurations 27 Interior /I Well Construction Configurations 28 Interior II Well Abandonment Configurations V LIST OF MAPS 'Maw No. rn Map 1 Tertian/ USDW, San Juan Basin Map 2 Upper Cretaceous USDW, San Juan Basin Map 3 Mesa Verde Group USDW, San Juan Basin Map 4 Gallup Formation & Equivalents, San Juan Basin Map 5 Dakota Formation USDW, San Juan Basin Map 6 Morrison Formation USDW, San Juan Basin Map 7 Morrison Formation and below, San Juan Basin Map 8 Type Areas for API-USDW Study Map 9 Head Map, all USDWs above Upper Cretaceous Map 10 Head Map, all USDWs above Mesa Verde Map 11 Head Map, all USDWs above Gallup Map 12 Head Map, all USDWs above Dakota Map 13 Head Map, all USDWs above Morrison Map 14 Head Map, all USDWs, San juan.Basin Map 15 Upper Cretaceous Residuals (0.45 psi/ft gradient) Map 16 Mesa Verde Residuals (0.45 psi/ft gradient) Map 17 Gallup Formation Residuals (0.45 psi/ft gradient) Map 18 Dakota Formation Residuals (0.45 psi/ft gradient) Map 19 Morrison Formation Residuals (0.45 psi& gradient) Map 20 Below Morrison Residuals (0.45 psi/ft gradient) Map 2 1 Upper Cretaceous Residuals (0.433 psi/ft gradient) Map 22 Mesa Verde Residuals (0.433 psi/ft gradient) Map 23 Gallup Formation Residuals (0.433 psi/ft gradient) Map 24 Dakota Formation Residuals (0.433 psi/ft gradient) Map 25 Morrison Formation Residuals (0.433 psi/ft gradient) Map 26 Below Morrison Residuals (0.433 psi/ft gradient) Map 27 Mesaverde Injection Residuals (.45 psi/ft gradient) Map 28 Mesaverde Injection Residuals (.433 psi/ft gradient) vi 1.0 SUMMARY AND CONCLUSIONS A methodology developed for obtaining Area of Review variances has beenapplied to the San Juan Basin of New Mexico. The general concept of themethodology is shown in Figure 1. The methodology uses four basic variancecriteria that were agreed to by a Federal Advisory Committee but expands upon those to provide a greater range of variance options. Elements of this study included, + defining thegeology and hydrogeology of the San Juan Basin with respect to petroleum production and groundwater occurrence + documenting thebasin exploration and development history + documentation andanalysis of historical state regulations pertaining to well construction and abandonment + constructing pressureand hydraulic headsurfaces for petroleum reservoirs and head surfacesfor underground sources of drinking water (USDWs), and preparing theresulting residual head maps for each combination of petroleum reservoirs and USDWs + accumulation of available well datafor a selectedsample of producing and abandonedwells and preparationof wellbore diagrams + application theof well evaluationprocedures to theselected population of wells and analysis of the results + evaluationofAOR variance opportunities within the San Juan Basin USDWs were identified in six hydrostratigraphicsystems, including Tertiary, Upper Cretaceous, Mesaverde, Gallup, Dakota, and Morrison. Petroleum reservoirs were grouped in a similar manner, with an additional classification for petroleum reservoirs below the Morrison. USDWs are absent at manySanJuan Basin fields. Oil and gas development began in the San Juan Basin prior to 1900. The oldest field currently undergoing waterflooding is the Rattlesnake field, which was discovered in 1924. The mostrecent field is the Miguel Creek field which was discovered in 1978. A correlation has been found to exist betweenfield age and the quality of well construction and abandonment practiceas 1 it is documented by available information. Wells constructed or abandoned in fields discovered since 1949 have been found to provide USDW protection. I Regulation of oil and gas production activity began in 1912. The New Mexico Oil Conservation Commission (NMOCC) was established in 1935. The first modern statewide rules were instituted in 1950. The current New Mexico Oil Conservation Division evolved from the NMOCC in 1975. Major revision of the rules occurredin 1981 in response to the EPA regulations developed under the Safe Drinking Water Act. It is believed that the rules establishedin 1950 have been effective in requiring that wellbore features are present to protect USDWs in wells constructed or abandoned since that time: Residual hydraulic head maps were prepared for eachof the petroleum reservoirs with respect to overlying USDWs. These maps are based on initial pressure surfaces and were constructed with drillstem test (bottomhole) pressures.