Offshore energy development in the Santa Barbara Channel can be broken into six periods. This division is not arbitrary. Each period is distinguished by differences in technology, location, economics of development, and policies governing development.

ABSTRACT This paper describes the California Offshore Oil and Gas Energy Resources (COOGER) Study, why Minerals Management Service developed the study, and the form that the study has taken. This paper evaluates how a collaborative process has been used for the COOGER Study, when collaborative studies can be used, how they should be structured, and some lessons for creating collaborative or cooperative studies.

ABSTRACT Inspired by the economic necessity of compressing the technical and economic evaluation time cycle, Mobil’s conventional project planning evaluation process was re-engineered. This new approach was successfully applied to a novel development plan for a major California offshore field. With 155 MMSTB of remaining recoverable oil, the South Ellwood Field is one of the larger oil development opportunities remaining in the continental United States. While portions of this field have been under production from Platform Holly since 1967, at least 65 percent of the recoverable original oil in place (OOIP) remains, Mobil’s “Clearview” Development Project would have used extended reach drilling from shore. The extended reach wells would have horizontal depth to true vertical depth ratios of up to 5:1. The development proposal included abandonment of Platform Holly. This paper focuses on the creation of a development plan for this major California offshore field. A self-directed, multi-disciplinary team identified and resolved several technical issues that could have allowed the transformation of the existing 4500 STB/day field to one producing 20,000+ STB/day. Technical issues addressed for the heterogeneous Monterey Formation include; hydrodynamic tilt of the oil/water contact; identification and mapping of various lithologies using seismic, logs and regional geology; productivity variations between lithologies; recovery factor range, natural fracture orientation and effects upon horizontal well trajectories; horizontal well production forecasts using advanced decline curve analysis and reservoir simulation; and the use of a stochastically based methodology for quantifying production profiles at various confidence levels. The re-engineering of the technical study methodology put a premium on team work, communication, and integration. As a result of this re-engineering, the previously planned three year technical/feasibility study was completed in 6 months. This paper reveals how a self-directed, multi-disciplinary, multi-worksite team integrated solutions into a unified reservoir description and a cohesive strategy for future development.

ABSTRACT Advances in drilling technology now enable the exploration for and development of offshore oil and gas resources without the installation of facilities and wells in offshore marine environments. This paper will discuss the resource potential for California tide and submerged lands (tidelands) and recent trends to develop this potential while providing increased environmental protection using “extended reach drilling” from existing onshore (upland) sites. Investigation of the economic feasibility as well as the regulatory and permitting process in developing California’s offshore resources through this drilling method will be presented. A prototype upland extended reach drilling development will be discussed for the South Ellwood Offshore Field, Santa Barbara County. This concept, entitled “Clearview,” has been endorsed by the staff of the State Lands Commission, local business groups and is actively promoted by the lessee, Mobil Oil Corporation. The aspects of the Clearview Project which make expanded development of the South Ellwood Offshore Field possible will be reviewed. This paper will examine past trends that shaped California offshore resource development policy and recent circumstances leading to the support of upland extended reach drilling. Royalty revenue sharing with impacted coastal communities may increase the likelihood of development using extended reach drilling and is presently under consideration by the staff of the State Lands Commission (SLC), the agency responsible for the development of tideland oil and gas resources in California.

The Santa Barbara-Ventura Basin province is located offshore southern California (fig. 1). This Federal offshore assessment province is within the western portion of the Transverse Ranges geomorphic province (which is so named because its eastwest orientation runs counter to the predominant north-northwest grain of the region’s major structural trends) and the western portion of the Santa Barbara-Ventura basin proper.

Several papers in this volume deal with the structure beneath the Santa Barbara Channel from opposing view points. These are the thickskinned structural interpretations versus the thin-skinned ones. In the thick-skin interpretations, high angle reverse faults cut the crust to the base of the seismic zone (see Yeats, this volume). In the thin-skinned model these reverse faults are actually active axial surfaces of fault-bend-folds above detachment ramps in the lower crust (see Novoa, this volume). The detachments are necessarily blind, and they do not crop out.

ABSTRACT A closely spaced data set of analog and digital (CDP) seismic reflection lines was used to map the structure of the offshore northwestern Santa Barbara basin and the offshore southern Santa Maria basin. East-west structures of the Santa Barbara margin between the Molino gas field and to the west of Point Conception are linear fold and fault trends offset by minor tear faults and, west of Gaviota, by the South Santa Ynez fault zone. The structures in both mapped areas are Plio-Pleistocene in age and most are active today. Offshore of Point Conception in the northwest corner of Santa Barbara basin the change from the east-west tectonic grain of the western Transverse Ranges and the northwest grain of the offshore southern Santa Maria basin occurs across a narrow, structurally complex zone. This “Disrupted Zone” begins near the State Lands/Federal OCS boundary west of Point Conception and extends to the west for several kilometers. Bordered on the east by the thrust faults of the Point Conception fault zone and on the west by a zone of right-lateral shear, the zone is 4 to 7.5 km in width. Orientations of folds, monoclinal flexures and faults within the zone are highly variable (east-west to north to northwest). Widest west of Point Conception, the zone narrows to the north of Point Arguello and becomes less well defined, It also lies on trend with the southern Hosgri fault zone. An older uplift, the Point Arguello-Conception-Amberjack (?) (PACA) high that trends to the southwest of the headland formed by the points, is overprinted by the Plio-Pleistocene structures. Today the tectonic border of the Western Transverse Ranges, including the Santa Barbara basin, is the “Disrupted Zone”. The older “PACA” high is the Paleogene boundary of the Santa Barbara and offshore southern Santa Maria basins.

ABSTRACT The Santa Barbara Channel basin, located in southern California, is undergoing significant shortening. We use contour and axial surface maps of several horizons and balance regional cross sections through the eastern and western Santa Barbara Channel, as well as structural profiles and surface restoration techniques, to analyze how the subsurface structures in this basin accommodate the deformation. Reflection seismic profiles show that some of the mapped structures are active (e.g. the Oak Ridge, the Blue Bottle, the Pitas Point, the Dos Cuadras, the Carpinteria and the Santa Rosa trends) and accommodate a large part of the shortening, whereas others are completely inactive (e.g. the Western Deep trend). Restoration of seismic profiles shows that structures in the basin grow by kink-band migration. In cross sections, we interpret that to the east, there are mainly two levels of faulting. The Oak Ridge trend develops above the deeper one, whereas the Dos Cuadras, the Pitas Point, the Carpinteria and the Blue Bottle trends develop on the shallow one. To the west, we interpret the existence of three levels of faulting. A mid-crustal detachment is the deepest one, the Blue Bottle and the Western Deep trends are developed above the shallowest one. The Santa Rosa trend is growing above an intermediate one. The axial surface and contour maps suggest that the Blue Bottle and Pitas Point trends end progressively to the west, accommodating an average of 2 to 4 km of shortening. The Oak Ridge trend terminates at a tear fault south of the Santa Barbara city. This fold accommodates about 11 km of slip. We show, using map view restoration, that slip involved in this trend is transferred to the west through a mid-crustal bedding parallel detachment fault. The Dos Cuadras trend extends beyond the mapped area both to the east, where it becomes the Ventura anticline, and to the west. We determine that the Dos Cuadras and Carpinteria trends accommodate about 11 km of shortening. The Santa Rosa trend is a new mapped trend in the southwestern area of the basin.

ABSTRACT A continuous 220 km long anticline underlies the Santa Monica Mountains and northern Channel Islands of southern California. This fold has been explained as the result of slip on a ramp in a blind thrust fault. Here we investigate the part of that structure including northwest Santa Rosa Island and southwest Santa Barbara basin. A U.S. Geological Survey (USGS) multichannel seismic reflection profile, USGS-808 was reprocessed and output in migrated depth and time. This profile, an industry multichannel profile, and numerous USGS high resolution reflection profiles were correlated to petroleum test well logs and to published data from Ocean Drilling Program (ODP) Site 893. A continuous fold limb dips north 10°-15° beneath northern Santa Rosa Island and the adjoining shelf and slope. This fold limb is cut by high-angle strike-slip faults on Santa Rosa Island, and by strands of the steeply S-dipping Santa Cruz Island fault at the shelf-break. The base of the fold limb is deformed by Pliocene slip on a blind S-dipping western continuation of the Oak Ridge-deep Mid-Channel fault. Neogene strata beneath central Santa Barbara Channel are nearly undeformed except that slight tilting and normal separation of Miocene strata is preserved across N-dipping faults. Steeply-dipping Pliocene and older strata associated with the North Channel fault are seen in wells beneath the northern margin of Santa Barbara basin, but are not imaged on USGS-808. The gently-dipping strata indicate that little shortening has been accommodated by folding and faulting across Santa Rosa Island or beneath much of Santa Barbara Channel. The observed wide fold limb can be created by less slip above a concave-up (listric) fault than by the more widely applied ramp-flat fault bend fold models. Progressive limb rotation is interpreted beneath the southern margin of Santa Barbara basin, consistent with a listric thrust model.

ABSTRACT Two contrasting views of the Oak Ridge fault in the Ventura basin have emerged: a thick-skinned view based on onshore subsurface oil-well data and a thin-skinned view based on interpretation of seismic profiles and dipmeter data from the Santa Barbara Channel. The offshore Oak Ridge structure is interpreted as an active axial surface above the ramp of a blind, south-vergent thrust; growth triangles in the kink band south of this surface contain parallel, north-dipping strata in which the kink band tapers toward the surface. In contrast, dips of growth strata onshore near the coast at Montalvo steepen with depth, evidence of progressive limb rotation and a steeply-dipping, large-displacement Oak Ridge fault. The onshore Oak Ridge fault is northward-vergent. West of Oak Ridge, the post-Saugus displacement is transferred via the ductile Rincon Formation to folding of the Ventura-Rincon anticline, also a north-vergent structure onshore and offshore. An onshore seismic line along a cross section documented by electric logs shows a narrow panel of north dips that could be the onshore termination of an offshore kink band mapped in the Santa Barbara Channel. North dips at greater depth in this seismic line do not correspond to well data and are artifacts of processing. Farther east, north dips are possible only if the kink band turns to the northeast, parallel to the Montalvo fault. The onshore-offshore controversy will only be resolved by comparing seismic profiles in the Santa Barbara Channel with subsurface well profiles in the same transect using well-log correlations as well as dipmeter data.

ABSTRACT The Conception submarine fan is located in the northwestern corner of the Santa Barbara basin, within the tectonically active western Transverse Ranges Province of southern California. This small radial fan heads off a series of small submarine canyons and slope gullies that were fed by the modern and ancestral Santa Ynez River, intermittent streams and longshore drift. A unique data set of high resolution analog to deep penetration, CDP seismic reflection profiles and records, collected along north-south/east-west tracklines was used for this study. These data were collected for or by the energy industry primarily between 1960-1985, and were augmented by boring logs and near-surface core and grab samples. Surface and deep-tow side scan sonar records over critical features (e.g. fan channels, faults, etc.) complete the data set. East-west trending oblique-slip faults and related folds control the position of shelf break along the northern margin of the basin. Barriers or tectonic dams along the shelf were formed by growing anticlinal folds and active faults and breached by streams incised along shear zones such as the south Santa Ynez fault and minor cross faults. At these points the small submarine canyons that fed the fan during low-stands of sea-level were established. Inactive today, this Quaternary fan extends from shelf break (-90 m) to the basin floor (-550 m), a distance of 25 km. In width the middle fan is 20 to 25 km across, while the lower fan is 35 km across where it is deflected eastwards along the southern or island margin of the basin. The fan is about 150 m thick and internally consists of four major, 30-40 m thick sand-thin mudstone sequences that represent low and high sea level stands. Uplift along the northern and western margins of the basin and the southern or island margin restricted the fan’s radial growth and progressively shifted its activity to the southeast toward the center of the basin. The southern edge of the fan laps onto the basin apron of the island or southern margin of the basin. The eastern edge of the fan is marked by an abrupt southwesterly deflection of the east-west trending isobaths that are typical of the northern slope. Internally this boundary is evidenced by a rapid change in seismic facies as slope mudstones interfinger with sand-rich fan deposits. Isopachs of the four seismic sequences of the fan document the offset or horizontal stacking of these sequences. The maximum thickness of each overlying sequence is offset horizontally from the maximum thickness of the underlying sequence. As a potential reservoir the Conception Fan offers four 30-45 m (maximum) thick sand-rich sequences separated by mud seals (3± m thick). Each sand sequence is topographically high along its axis of maximum thickness. The entire fan is encased in mud-as it overlies mudstones of the Pico Formation and is covered by a high-stand mud deposit. An offset stacking model of depositional sequences or “fan lobes” provides a valuable tool for exploration. Examples of offset stacking include the Lathrop and the Winters Formation fans of the northern Great Valley and Neogene fans in southern California.

The contour interval is 1,000 feet, which is too coarse to resolve many local details, even though the structural configurations are derived from detailed 3D interpretations in some areas. 3. The Monterey Formation was selected as being the most representative horizon to illustrate the results of the tectonic events that have shaped the area since the end of Monterey deposition approximately 6 million years ago. The Monterey is also an important petroliferous formation that is the source and reservoir for much of the oil and gas that has been and will be produced in the future from the Santa Barbara Channel.

A north-south cross-section across the Santa Barbara Channel between the northwestern end of Santa Rosa Island and the crest of the Santa Ynez Mountains north of Canada de Molino (Plate II) was constructed using previously mapped surface geology, seismic reflection data, and geologic data from exploratory wells and oil and gas accumulations along and near the line of section. It shows Upper Cretaceous through Cenozoic strata dipping toward the Channel from both flanks, gently north from the crest of the Northern Channel Islands anticlinorum on the south, and more steeply southward from the complexly folded and reverse-faulted south flank of the Santa Ynez Mountains on the north.

This structure cross section (Plate III), with true vertical and horizontal scale, crosses the Santa Barbara Channel from Carpinteria through the east end of Santa Cruz Island. Although it is not the first such cross section, it incorporates more than 20 exploratory wells with detailed electric log and paleontological correlations, considerable modern 2-D seismic data and, of course, outcrop geology by Dibblee (1986) and Weaver, et al. (1969) at either end. It depicts all of the important faults, folds, and uplifts of the offshore Ventura basin in considerable detail, and even though it does not exactly cross several important producing fields, the pertinent subsurface geology is considered in drawing the section (c.f. Chevron’s Summerland Offshore field; Texaco’s and Nuevo Energy’s (ex-Unocal) Pitas Point gas field; Nuevo Energy’s (ex-Unocal), Chevron’s, and Pauley’s Santa Clara field; Chevron’s Sockeye field).

The Rincon oil field is located approximately ten miles west of the city of Ventura, California along the Rincon Anticlinal Trend (Figure 1). The offshore area is the westward extension of the onshore Rincon oil field. The offshore area is developed from five subsurface leases (Figure 2). These include PRC 145, PRC 410, PRC 427, PRC 429, and PRC 1466. The redevelopment of PRC 1466 is the subject of this paper. PRC 1466 is located immediately south-southwest of Punta Gorda and a portion of its northeastern boundary is coincident with the shoreline at that location. Development of this 1175 acre lease is from a man- made drilling and production island. A causeway, 2700 feet in length, connects the manmade Rincon Island to the shore. The causeway allows one-way vehicle traffic on and off the island and contains a six-inch diameter gas pipelines, a six-inch diameter oil pipeline, a high voltage power line, and telecommunications lines along the flanks of its deck.