Open Access Research Article

Optimal Spacing of the Wolfcamp in the Delaware Basin

Ahmed Alzahabi1*, A Kamel1, A Harouaka1 and A Alexandre Trindade2

1Petroleum Engineering Department, University of Texas-Permian Basin, Odessa, TX, USA

2Department of Mathematics and Statistics, Texas Tech University, Broadway and Boston, Lubbock, USA

Corresponding Author

Received Date: February 23, 2021;  Published Date: March 22, 2021


Proper well spacing for horizontal wells is one of the missing pieces for the Delaware Basin development in the Wolfcamp Formation. In the Wolfcamp formation in the Delaware Basin, well spacing varies with formation characteristics (rock and fluid) across the Basin. Finding the spacing intervals between horizontal wells right is crucial to maximizing productivity and estimated ultimate recovery (EUR) while avoiding detrimental frac hits and cross-well pressure and fluid interference during stimulation and production.

Along with the various parameters affecting development, well patterns and completion methodologies are having the highest impact. Both parameters show a significant impact on the drainage area of wells and may in turn affect optimal spacing between the wells. The model outcomes are expected to improve recovery efficiency, oil production, and minimize detrimental frac hits and cross-well pressure and fluid interference during stimulation and production. A pool of private production and spacing data were analyzed in conjunction with data analytics. This step led to a newly developed model to optimize well spacing.

The work may lead to an optimal spacing for the stacked Delaware Basin, and contribute to a better understanding of infill Wolfcamp child wells relative their offset parent wells. Our model within the Wolfcamp may be applied to various sections and formations across the Permian Basin. Current workflows and spacing advisors require use of numerical reservoir simulation and fracture simulation. Drainage area, spacing, reserves, recovery factors, and fracture height and width are the main unknown variables in unconventional plays. Application of data analytics with production, spacing, life of the well on production, and completion data is anticipated to resolve some of these issues.


• Kf= fracture permeability

• wfp= propped fracture closed width

• 200, 100, 40/70, 30/50, 20/40, 30/70 = a descriptor used to describe the size of the proppant being pumped.

• Age = the difference in number of days between the time the well was completed and 01/01/2001.

• Avg. Prop. Concentration = the lbs of proppant pumped per fluid gallons pumped.

• Avg. Rate = the average rate at which the mixture is pumped downhole to create the fractures.

• Cluster spacing = the distance between the clusters within the stage.

• Cluster = a set of perforations arranged in a certain pattern to achieve the optimal completion.

• Clusters per stage = the number of clusters used in each stage.

• Comp Date = the date the well was completed.

• Completed feet = the calculated distance between the top perf and bottom perf where the fractures occur.

• County = the county where the well was drilled.

• County Variable = a numeric variable to distinguish between counties.

• Degradation = the amount of overlap divided by total rectangular area.

• Fluid Bbls = the amount of fluid pumped downhole to initiate fracture and place proppant.

• Fluid Gal/Cluster = the amount of fluid pumped per cluster.

• Fluid Gal/Ft = fluid volume in gallons per foot.

• Fluid Gal/Ft = the amount of fluid pumped per completed foot.

• Fluid Gal/Perf = the amount of fluid pumped per perforation.

• GOR Ratios = a metric used to determine the amount of gas produced per oil produced (SCF/STB).

• IP = initial production rates.

• IP = the amount of oil produced by a new oil well, measured in B/D (barrels of oil per day) or BOE/D (barrels of oil equivalent per day).

• IP 30, 90, & 180 = calculations taking a rolling average by number of days described (30, 90, or 180) and then using the maximum value obtained for oil, gas and water.

• ISIP/Ft = instantaneous shut in pressure once a stage has been completed and frac pumps are shut down.

• Linear Gel = a fracturing fluid supplemented with different polymers which increase its ability to carry proppant.

<• Max Prop. Concentration = the proppant concentration begins with mostly fluid and then is built up to a maximum concentration of pounds of proppant per fluid gallon.

• Max. Rate = the maximum rate achieved pumping mixture into fractures.

• Number of stages = Whenever a plug is set, perforations are created, the reservoir is fractured with fluid, and then another plug is set, it is called a stage.

• Oil, Gas, MBOE EUR= the estimated ultimate recovery of oil and gas, MBOE – Oil + Gas/6.

• Perfs = the number of holes created from the charges that are inserted downhole in sets of perforations called clusters designed in different patterns to achieve optimal completion.

• Perfs/Clusters = the number of perforations used in each cluster.

• Prop. Lbm = the amount of proppant pumped with the fluid to keep the created fractures open.

• Prop. Lbm/Cluster = the amount of proppant pumped per cluster.

• Prop. Lbm/Ft = the amount of proppant pumped per completed foot.

• Prop. Lbm/Perf = the amount of proppant pumped per perforation.

• Proppant Lbm = Mass of proppants

• Rate/Cluster = the average rate per cluster.

• Rate/Ft = the average rate per completed foot.

• Rate/Perf = the average rate per perf.

• Reservoir = the formation in which the lateral was drilled (i.e. Wolfcamp A, Wolfcamp LA, Wolfcamp MA).

• Reservoir = the formation that the lateral was drilled (i.e. Wolfcamp A, Wolfcamp LA, Wolfcamp MA).

• Reservoir Variable = a numeric variable distinguishing between reservoirs Wolfcamp C-D and Wolfcamp A.

• Reservoir Variable = a numeric variable distinguishing between reservoirs Wolfcamp C-D and Wolfcamp A.

• ROA= Rectangular Overlap Area: the area of overlap from wells in the same section with one another determined by their legal spacing location. Assuming a Xf off 770’ and Hf of 200’ and rectangular drainage area.

• Slickwater = water with chemicals added to speed up the rate at which it can be pumped to create more fractures.

• Stage length = the length of each stage, a good indicator for normalizing stages for lateral length.

• TVD = the furthest vertical depth drilled.

• UWI = a unique well identifier for every well; each set of numbers stands for a unique location and well identifier (i.e. county, state, horizontal, pilot).

• WCUT = Water cut; a metric used to determine the amount of water produced per oil produced. (Water / (Water + Oil)).

• Yield= Condensate yield, MMSCF/STB.

Keywords: Optimal production; Wolfcamp formation; Fracture driven interaction; Well spacing

Signup for Newsletter
Scroll to Top