Contrasting Marcellus Production in Ritchie, Pleasants, Tyler, Doddridge and Harrison Counties, West Virginia
John Ward¹ and James Schuler²
¹PetroEdge Energy LLC. Houston, TX, [email protected]
²PetroEdge Energy LLC., Williamstown, WV
During the early drilling of vertical wells in the Marcellus in 2006 and 2007 in West Virginia, two operators (PetroEdge Resources and Triad Resources) developed production from vertical wells in Ritchie, Pleasants and Tyler Counties West Virginia. When the production of these wells is compared to newer vertical wells in Doddridge, Western Harrison and Tyler Counties, the old wells have reduced production performance.
One explanation for performance difference is that the Marcellus reservoir is low pressure where a pressure seal created by the overlying Tully Limestone is breached. Early cross sections and production performance in Ritchie County demonstrated that it is likely that seal integrity decreases when the thickness of the Tully to Marcellus isochore is very thin generally less than 20 ft.
The best production per foot in the five county area is not dominated by gross rock thickness since the Marcellus is less than 50 feet thick, but by a facies within the Union Springs member in Doddridge and Harrison Counties that is in the pressure sealed regime, and that has high porosity and permeability in a low clay, high quartz, high TOC rock. From west to east across Harrison County the relative per foot recovery in the total Marcellus decreases even though the gross isochore increases as the Upper Oatka Creek member develops thickness with higher clay, lower TOC and lower quartz concentration leading to decreased porosity and permeability.
Analysis of the production data of the Marcellus has areas of Pleasants and Ritchie Counties that have typically been interpreted to have reduced productivity caused by lack of reservoir pressure. It is possible that not only does pressure control per foot productivity, but there may be a contribution caused by confusion in stratigraphic correlation. When the Tully Limestone is present, identification of the Taghanic uncomformity on wireline logs is straightforward. Once the Tully Limestone is stripped, the Marcellus is at subcrop. Since the Genesee Shale above the unconformity is similar on wireline logs to the Marcellus, separation of the two formations is difficult when they are directly juxtaposed. This interpretation suggests that the gross Marcellus isochore continues to thin below the unconformity surface. Thus, the western apparent constant or increase in Marcellus thickness is the result of correlation confusion between the Marcellus, and the combined Marcellus and Genesee Shale.
AAPG Search and Discovery Article #90154©2012 AAPG Eastern Section Meeting, Cleveland, Ohio, 22-26 September 2012