Decoding the Permian

The initial commercial oil well in the Permian Basin was completed in 1921, the first of thousands of wells that would ultimately be drilled in this oil-rich region.

Despite its ups and downs over time, the Permian today is hot, and haute.

Long the domain of smaller independents for the most part, the region now is also attracting the big, big players. Among others, super major ExxonMobil recently staked an ownership claim there, which is forecast to pump oil for a couple of decades (see related story on page 12).

The Greater Permian sprawls across a wide expanse of west Texas, reaching into southeastern New Mexico. Within the Basin, the two sub basins Midland and Delaware are perhaps the most high profile. The Central Basin platform lies between the two.

With its innumerable hydrocarbon-bearing targets, including shale zones aplenty, this part of the oil patch really came into its own with the proliferation of horizontal drilling. The practice of commingling production from two or more zones became the rage soon thereafter.

Incorporating Seismic Data

Even so, complexity rules and operators continue to investigate how to up their game with lower costs and more efficient production.

The geology poses some daunting challenges for the lateral wellbores, often changing significantly with no warning and thereby negating production at certain stages of the procedure, among other complications.

Midland-based Fasken Oil and Ranch Ltd. has long been drilling in the Permian – the Midland Basin in particular. Today, the company is working diligently to determine the best practices to optimize the lower Permian-age Wolfberry Play here where it has a wrap on 165,000 acres.

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The initial commercial oil well in the Permian Basin was completed in 1921, the first of thousands of wells that would ultimately be drilled in this oil-rich region.

Despite its ups and downs over time, the Permian today is hot, and haute.

Long the domain of smaller independents for the most part, the region now is also attracting the big, big players. Among others, super major ExxonMobil recently staked an ownership claim there, which is forecast to pump oil for a couple of decades (see related story on page 12).

The Greater Permian sprawls across a wide expanse of west Texas, reaching into southeastern New Mexico. Within the Basin, the two sub basins Midland and Delaware are perhaps the most high profile. The Central Basin platform lies between the two.

With its innumerable hydrocarbon-bearing targets, including shale zones aplenty, this part of the oil patch really came into its own with the proliferation of horizontal drilling. The practice of commingling production from two or more zones became the rage soon thereafter.

Incorporating Seismic Data

Even so, complexity rules and operators continue to investigate how to up their game with lower costs and more efficient production.

The geology poses some daunting challenges for the lateral wellbores, often changing significantly with no warning and thereby negating production at certain stages of the procedure, among other complications.

Midland-based Fasken Oil and Ranch Ltd. has long been drilling in the Permian – the Midland Basin in particular. Today, the company is working diligently to determine the best practices to optimize the lower Permian-age Wolfberry Play here where it has a wrap on 165,000 acres.

Fasken has hundreds of successful vertical wells to its credit and soon will kick off its first horizontal wellbore in the play.

The Wolfberry moniker originates from the initial commingling of oil from the long producing Sprayberry sandstone and the deeper packed-limestone Wolfcamp formation. The Wolfberry interval in the area of interest includes several Pennsylanian to Guadalupian-age formations.

Working in conjunction with Drilling Info, principally Samantha Siegel, the method of the ongoing program entails incorporation of seismic data into a multivariate data analysis of the play, according to Fasken chief geophysicist Glenn Winters.

The engineering, seismic and geological information comprising the robust data set the two entities are working with includes open and cased hole logs, completion information, core data, four years of production history data and recently acquired 3-D seismic data.

The data set encompasses more than 1,900 wells with production history of more than 50 horizontal wells, according to Winters. The company has over 600 square miles of contiguous merged and reprocessed seismic data, which has been subjected to both pre- and post stack inversion.

Winters noted that topics to be investigated during the next couple of years include:

  • Vertical versus horizontal wellbores
  • Well spacing and landing targets
  • Conventional versus unconventional landing targets
  • Completion practices

Fasken owns the 3-D survey outright, which positioned the company in a good spot early on.

“Basically, we organized this big 3-D group shoot and let other people in it,” Winters said. “Now, because we have that good chemistry, we’ve been getting production from some of the other companies.

“Since we own all of the seismic data and the majority of the land, we can share information because we’re not competing with anyone,” he emphasized.

Even though Fasken has more than 500 vertical wells on production in the Wolfberry, horizontal wells in the area are just outside the limits of its acreage and are owned by others. Without the sharing agreement, all of the available production history it uses would originate from verticals.

Note to anyone unfamiliar with Texas oilfields: the state doesn’t calculate production per well, but by lease, so it’s hard to find out well quality by state records. So if you need to model your reservoir and not break the bank while doing so, the Fasken/Drilling Info project is tailor made.

“The two software packages we’re using – SeisWare and Transform – are significantly less expensive tools that easily communicate with any other software packages,” Winters emphasized.

“We are coming up with a workflow that uses this great data set (we’ve assembled) to then use as a procedure in how to go ahead and do this yourself,” he noted. “You then can continually update your models.”

Winters said they used SeisWare for their seismic interpretation.

Integrating the Data

Having so much well control including the information from neighboring producers, the Fasken team was able to use its vertical wells to create a porosity model. Then they integrated that with production information to arrive at a probability production model.

“Once you have the procedure and a sequence, then it’s just a matter of keeping on adding wells to it, and you can continually update the model using software that a small company can afford to use with only a little training,” Winters exclaimed.

It helps that the software is becoming so much easier to use, meaning the field scientists can actually do the work independently.

“Using Transform software, we’re able to use multivariate statistics to find relationships not easily observed in conventional crossplots. We then use non-linear regressions as a predictive analysis tool to investigate these relationships.

“The ability to calibrate seismic to well logs and then calculate additional volumes from multivariate statistics proves to be a valuable tool,” he added.

“Ultimately, the goal for the geoscientist and reservoir engineer is to create a dynamic model that integrates how production on a lease fluctuates over time with the increase in density of vertical wells,” Winters said, “and how the completion activities and perforations when combined with geology and geophysics helps to identify the best way to harvest the reservoir.”

The current program involving the Fasken holdings will yield an unexpected bonus for future petroleum industry professionals in particular.

Winters noted that Fasken intends to allow Drilling Info to use this part of their data for instructional purposes in several universities in the oil patch.

“Fasken is going to provide this data as a great training set,” he exclaimed.