PTRL3030/5021/6021: Reservoir Characterisation Assignment 1
This individual assignment should be handed in before 5pm on Wednesday, 5th July electronically as PDF or word document as single file. Note that tables 1 and 2 are available as text file on Moodle – please load the table corresponding to your student ID.
Q1. Consider the data publicly available from fourteen wildcat wells in the National Petroleum Reserve in Alaska (https://certmapper.cr.usgs.gov/data/PubArchives/of00-200/wells/WELLIDX.HTM). The wells are distributed as given in Fig. 1 with corresponding formation tops (in ft) and exact well locations given in Tab. 1.
Figure 1: Well locations of 14 wildcat wells given by public USGS report 00-200.
Table 1: Formation tops and well locations for 14 wildcat wells given by public USGS report 00-200.
Well # Name Torok Pebble SH Kingak SH Sag River SS Shublik BasementLatitude Longitude 1 Awuna XXXXXXXXXX023 2 East Simpson XXXXXXXXXX XXXXXXXXXX XXXXXXXXXXKugrua XXXXXXXXXX XXXXXXXXXX XXXXXXXXXXLisburne XXXXXXXXXX 5 Seabee XXXXXXXXXX XXXXXXXXXXSouth Barrow XXXXXXXXXX XXXXXXXXXXSouth Barrow XXXXXXXXXX XXXXXXXXXX XXXXXXXXXXSouth Barrow XXXXXXXXXX XXXXXXXXXXSouth Barrow XXXXXXXXXX XXXXXXXXXX XXXXXXXXXXSouth Barrow XXXXXXXXXX XXXXXXXXXX XXXXXXXXXXTulageak XXXXXXXXXX XXXXXXXXXX XXXXXXXXXXTunalik XXXXXXXXXX XXXXXXXXXX XXXXXXXXXXWalakpa XXXXXXXXXX XXXXXXXXXX XXXXXXXXXXWalakpa XXXXXXXXXX XXXXXXXXXX156.953
a. (10 marks) Initialise the random number generator in Matlab with your student number. Starting in pristine state after this initialisation, draw an integer in the interval [1;3]. Here ‘1’ stands for the Torok formation, ‘2’ for Pebble Shale and ‘3’ for Sag River Sandstone. Then choose five wells with valid tops (Tab. 1) randomly using a similar approach in Matlab. b. (10 marks) Discretise the chosen well locations on a 50x50 grid and visualize the grid (e.g. use 0 for a cell containing no well and 1 for a well-containing cell). c. (20 marks) For the chosen wells and formation enter the respective formation tops at their locations in the grid. Populate the 50x50 grid with interpolated formation tops from the known points using i) nearest neighbour and ii) inverse distance weighting techniques (p=2). Discuss the resulting maps.
Q2. Consider a log quality task for the same field as in Q1. a. (15 marks) For the first well as chosen above (with valid log data in the respective interval), carry out a quality control for RHOB, NPHI and DT in the Sag River Sandstone unit. b. (15 marks) Calculate the correlation coefficients between RHOB, NPHI and DT (in pairs).
Q3. Consider a layered sequence discovered in a fluvial delta with some evidence of cross-bedding. The bottom layer is a horizontally continuous shale layer with varying height and has been eroded at places by a river system. The middle layer (sandstone) is heterogeneous and only partially continuous as the river changed direction over time and filled in the channels of the layer below. The top layer is a sandstone of low permeability. It exhibits a continuous top and bottom surface, covers the channel system, and varies in thickness. a. (15 marks) Choose an appropriate grid to discretise this layered system and give a reason for your approach. Illustrate your argument graphically. b. (15 marks) Choose three physical measurements to capture essential properties to characterise flow. Pay attention to both horizontal/vertical resolution and field of view. How do these measures help you to characterise the reservoir?